Solar System, Galaxy, Universe
Artist illustration of the Milky Way. Image credit: NASA
Our Solar System is like a small oasis in our galaxy, which is an tiny island in the Universe. Understanding our Solar system, galaxy, and Universe, you need to know a few basic facts about the relative size of each. Here are quite a few facts about each. Hopefully, they will help you better understand the Universe around you.
Our Solar System is the smallest of the items in this article, so let’s start there. There are several ways to consider the size of the Solar System. I prefer to say it ends at the heliopause(the edge of the heliosphere). That is the end of the Sun’s influence on the interstellar medium and occurs at 90 AU in all directions. The heliosphere is not perfectly round, so the 90 AU is a give or take number. If you tried to put the size of the Earth in perspective, it would be about the size of a single peppercorn when compared to the Solar System. Scientists are just now getting their first solid data from the heliosphere. Voyager 1 and Voyager 2 are leaving the Solar System and continue return signals. No one is sure when the probes will cease to transmit.
The Solar System is just a tiny portion of the Milky Way galaxy. Our’s is a barred spiral galaxy and the Solar System is in a small spur off of one arm called the Orion Spur. There are 200 billion stars in the galaxy, but they are very far apart. The star closest to the Sun is in the Alpha Centauri system. That star is a short 4 light years, 37,842,921,890,323.2 km from ours. Just a short hop, skip, and jump from here in galactic terms.
That brings us to the Universe. The size of the Universe is impossible to calculate. Everywhere around us, the Universe is expanding and the distances to other galaxies are increasing. Current technology could never hope to measure many of the distances involved. That should change as the many types of telescopes and branches of astronomy become more advanced.
About the Sun
The Sun is a huge ball of incandescent plasma at the center of our Solar System. It accounts for more than 99% of the mass of the Solar System, and provides all the energy we need for life here on Earth.
The Sun’s diameter is 1,392,000 kilometres or 865,000 miles; that’s 109 times the diameter of the Earth. You could fit 1.3 million planets the size of the Earth into the Sun. Everything in the Solar System orbits around the Sun, including 8 planets and their moons, many dwarf planets, asteroids, comets and dust.
The surface of the Sun that we can see is called the photosphere, and it has an average temperature of about 5,800 kelvin. This is the point at which photons generated inside the Sun finally reach the vacuum of space. But if you could descend down into the Sun, you would find the temperature and pressure increasing until you reached the core of the Sun. At the core, the temperature is 15.7 million kelvin and the pressure is sufficient to support nuclear fusion. This is where protons are merged together to form atoms of helium, releasing tremendous amounts of energy.
Because the Sun is made of plasma, it’s also highly magnetic. It has north and south magnetic poles like the Earth, and the magnetic field lines create the activity we see on the surface. The darker sunspots are created when magnetic field lines pierce through the Sun’s photosphere. Coronal mass ejections and solar flares occur when these magnetic field lines snap and reconfigure. The amount of activity on the Sun rises and falls over an 11-year cycle. At the low point, called solar minimum, there are few, if any sunspots. And then at the high point of the cycle, solar maximum, there are the most sunspots and the greatest amount of solar activity.
The Sun takes about 1 month to rotate once on its axis; however, this is a rough estimate because the Sun is a ball of plasma. Some parts of the Sun rotate faster than other parts, so it’s hard to say when it has completed a full rotation.
The Sun is composed almost entirely of hydrogen (74%) and helium (25%), with other trace elements. The innermost layer of the Sun is the core, where the nuclear fusion reactions are taking place. Outside that is the radiative zone, where photons of gamma radiation created in the core are emitted and absorbed by hydrogen atoms. A single photon can take 100,000 years to finally get through the radiative zone. Outside the radiative zone is the convective zone, where bubbles of plasma rise and fall like a lava lamp.
The Sun has been around for 4.6 billion years, and it’s expected to last for another 7 billion years or so. Once all the usable hydrogen in the core runs out, the Sun will expand outward into a red giant, consuming the inner planets (maybe even Earth). Then it will slough off its outer layers and collapse inward to become a white dwarf star.
Only about 5% of stars in the Milky Way are larger than the Sun; the vast majority are smaller red dwarf stars. Some of the biggest stars can be 100,000 times brighter and contain 100 times more mass. The Sun is also relatively young, a member of the Population I group of stars. Older stars, which formed billions of years before the Sun are Population II stars and have less heavier elements in them. The oldest stars are Population III stars, formed just after the Big Bang, but these are purely theoretical.
Earth
Earth
We live on it. We exploit it. We take its presence for granted, but, in general, we know very little about it. It is the planet that we live on: Earth. Here on Universe Today it is our personal mission to make sure that we provide as much information as possible about our planet to anyone who is interested in learning it. In the dozens of links below you will find more information than you could possible assimilate in a single night, so here are a few facts to help pique your interest enough to delve through all of the links provided.
The Earth was formed about 4.6 billion years ago through a process called accretion. In the solar nebula that was left over after the formation of the Sun, all of the planets began to accrete mass. It all began with one larger body slowly impacting smaller bodies over and over. Some of these were as small as a single particle of dust others were several kilometers in diameter.
The Earth only rotates because of leftover momentum from the solar nebula. Each molecule in the cloud had its own momentum, and as they came together, their combined momentum added up and was conserved(see the theory of conservation of momentum). As the Earth accreted more material, the momentum of that material contributed to its rotation.
Interesting Facts About Earth
Plate tectonics keep the planet comfortable
Earth is the only planet in the Solar System with plate tectonics. The outer crust of the Earth is broken up into regions known as tectonic plates. These are floating on top of the magma interior of the Earth and can move against one another. When two plates collide, one plate can go underneath another.
Earth is the only planet in the Solar System with plate tectonics. The outer crust of the Earth is broken up into regions known as tectonic plates. These are floating on top of the magma interior of the Earth and can move against one another. When two plates collide, one plate can go underneath another.
This process is very important. When microscopic plants in the ocean die, they fall to the bottom of the ocean. Over long periods of time, the remnants of this life, rich in carbon, are carried back into the interior of the Earth and recycled. This pulls carbon out of the atmosphere, which makes sure we don’t get a runaway greenhouse effect, like what happened on Venus.
Without the plate tectonics, there’d be no way to recycle this carbon, and the Earth would overheat.
Earth is almost a sphere
The Earth’s shape could be described as an oblate spheroid. It’s kind of like a sphere, but the Earth’s rotation causes the equator to bulge out . What this means is that the measurement from pole to pole is about 43 km less than the diameter of Earth across the equator.
The Earth’s shape could be described as an oblate spheroid. It’s kind of like a sphere, but the Earth’s rotation causes the equator to bulge out . What this means is that the measurement from pole to pole is about 43 km less than the diameter of Earth across the equator.
Even though the tallest mountain on Earth is Mount Everest, the feature that’s furthest from the center of the Earth is actually Mount Chimborazo in Ecuador.
Earth is mostly iron, oxygen and silicon
If you could separate the Earth out into piles of material, you’d get 32.1 % iron, 30.1% oxygen, 15.1% silicon, and 13.9% magnesium. Of course, most of this iron is actually down at the core of the Earth. If you could actually get down and sample the core, it would be 88% iron. 47% of the Earth’s crust consists of oxygen.
If you could separate the Earth out into piles of material, you’d get 32.1 % iron, 30.1% oxygen, 15.1% silicon, and 13.9% magnesium. Of course, most of this iron is actually down at the core of the Earth. If you could actually get down and sample the core, it would be 88% iron. 47% of the Earth’s crust consists of oxygen.
70% of the Earth’s surface is covered in water
When astronauts first went into the space, they looked back at the Earth with human eyes for the first time, and called our home the Blue Planet. And it’s no surprise. 70% of our planet is covered with oceans. The remaining 30% is the solid ground, rising above sea level.
When astronauts first went into the space, they looked back at the Earth with human eyes for the first time, and called our home the Blue Planet. And it’s no surprise. 70% of our planet is covered with oceans. The remaining 30% is the solid ground, rising above sea level.
The Earth’s atmosphere extends out to 10,000 km
The atmosphere is thickest within the first 50 km or so, but it actually reaches out to about 10,000 km above the surface of the planet. This outermost layer of the atmosphere is called the exosphere, and starts about 500 km above the surface of the Earth. As we said, it goes all the way up to 10,000 km above the surface. At this point, free-moving particles can actually escape the pull of Earth’s gravity, and be blown away by the Sun’s solar wind.
The atmosphere is thickest within the first 50 km or so, but it actually reaches out to about 10,000 km above the surface of the planet. This outermost layer of the atmosphere is called the exosphere, and starts about 500 km above the surface of the Earth. As we said, it goes all the way up to 10,000 km above the surface. At this point, free-moving particles can actually escape the pull of Earth’s gravity, and be blown away by the Sun’s solar wind.
But this high atmosphere is extremely thin. The bulk of the Earth’s atmosphere is down near the Earth itself. In fact, 75% of the Earth’s atmosphere is contained within the first 11 km above the planet’s surface.
Want more planet Earth facts? We’re halfway through. Here come 5 more.
The Earth’s molten iron core creates a magnetic field
The Earth is like a great big magnet, with poles at the top and bottom of the planet, near to the actual geographic poles. This magnetic field extends from the surface of the Earth out thousands of kilometers – a region called the magnetosphere.
The Earth is like a great big magnet, with poles at the top and bottom of the planet, near to the actual geographic poles. This magnetic field extends from the surface of the Earth out thousands of kilometers – a region called the magnetosphere.
Be grateful for the magnetosphere. Without it particles from the Sun’s solar wind would hit the Earth directly, exposing the surface of the planet to significant amounts of radiation. Instead, the magnetosphere channels the solar wind around the Earth, protecting us from harm.
Scientists think that the magnetic field is generated by the molten outer core of the Earth, where heat creates convection motions of conducting materials. This generates electric currents that create the magnetic field.
Earth doesn’t take 24 hours to rotate on its axis
It’s actually 23 hours, 56 minutes and 4 seconds. This is the amount of time it takes for the Earth to completely rotate around its axis; astronomers call this a sidereal day. Now wait a second, that means a day is 4 minutes shorter than we think it is. You’d think that time would add up, day by day, and within a few months, day would be night, and night would be day.
It’s actually 23 hours, 56 minutes and 4 seconds. This is the amount of time it takes for the Earth to completely rotate around its axis; astronomers call this a sidereal day. Now wait a second, that means a day is 4 minutes shorter than we think it is. You’d think that time would add up, day by day, and within a few months, day would be night, and night would be day.
Remember that the Earth orbits around the Sun. Every day, the Sun moves compared to the background stars by about 1° – about the size of the Moon in the sky. And so, if you add up that little motion from the Sun that we see because the Earth is orbiting around it, as well as the rotation on its axis, you get a total of 24 hours. Now that sounds like the day we know.
A year on Earth isn’t 365 days
It’s actually 365.2564 days. It’s this extra .2564 days that creates the need for leap years. That’s why we tack on an extra day in February every year divisible by 4 – 2004, 2008, etc – unless it’s divisible by 100 (1900, 2100, etc)… unless it’s divisible by 400 (1600, 2000, etc).
It’s actually 365.2564 days. It’s this extra .2564 days that creates the need for leap years. That’s why we tack on an extra day in February every year divisible by 4 – 2004, 2008, etc – unless it’s divisible by 100 (1900, 2100, etc)… unless it’s divisible by 400 (1600, 2000, etc).
Earth has 1 moon and 2 co-orbital satellites
As you’re probably aware, Earth has 1 moon (The Moon). But did you know there are 2 additional asteroids locked into a co-orbital orbits with Earth? They’re called 3753 Cruithneand 2002 AA29. We won’t go into too much detail about the Moon, I’m sure you’ve heard all about it.
As you’re probably aware, Earth has 1 moon (The Moon). But did you know there are 2 additional asteroids locked into a co-orbital orbits with Earth? They’re called 3753 Cruithneand 2002 AA29. We won’t go into too much detail about the Moon, I’m sure you’ve heard all about it.
3753 Cruithne is 5 km across, and sometimes called Earth’s second moon. It doesn’t actually orbit the Earth, but has a synchronized orbit with our home planet. It has an orbit that makes it look like it’s following the Earth in orbit, but it’s actually following its own, distinct path around the Sun.
2002 AA29 is only 60 meters across, and makes a horseshoe orbit around the Earth that brings it close to the planet every 95 years. In about 600 years, it will appear to circle Earth in a quasi-satellite orbit. Scientists have suggested that it might make a good target for a space exploration mission.
Earth is the only planet known to have life
We’ve discovered past evidence of water on Mars, and the building blocks of life on Saturn’s moon Titan. We can see amino acids in nebulae in deep space. But Earth is the only place life has actually been discovered.
We’ve discovered past evidence of water on Mars, and the building blocks of life on Saturn’s moon Titan. We can see amino acids in nebulae in deep space. But Earth is the only place life has actually been discovered.
But if there’s life on other planets, scientists are building the experiments that will help find it. A new rover called the Mars Science Laboratory will be heading to Mars in the next few years, equipped with experiments that can detect life in the soil on the Red Planet. Giant radio dishes scan distant stars, listening for the characteristic signals of intelligent life reaching out across interstellar space. And new space telescopes, such as the European Space Agency’s Darwin mission might be powerful enough to sense the presence of life on other worlds.
But for now, Earth is the only place we know where there’s life. Now that is an interesting fact.
The surface area of the Earth is 510 million square kilometers or 5.1×108 km2. The Earth is a water heavy planet, so, if you break its surface area into water and land segments, it would look like this: land 149 million km2, water 361 million km2.
Surface Area of the Earth
The surface area of the Earth is 510 million square kilometers or 5.1×108 km2. The Earth is a water heavy planet, so, if you break its surface area into water and land segments, it would look like this: land 149 million km2, water 361 million km2.
Let’s look at how the surface area of the Earth compares to the surface area of the other planets in our Solar System and our Moon.
| Mercury | 75 million km2 or 10% of Earth’s |
| Venus | 460,000,000 km |
| Mars | 145 million2 or 28% of Earth’s |
| Jupiter | 6.2 x 1010 km2 or 122 times larger than Earth |
| Saturn | 4.27 x 1010km2 or 84 times larger than Earth |
| Uranus | 8.1×109 km2 or 16 times larger than Earth |
| Neptune | 7.64 x 109 km2 or 15 times larger than Earth |
| The Moon | 37.9 million km2 or 7% of the Earth’s |
Now that you know how the surface area of the Earth stacks up against the other planets in our Solar System, here are a few other interesting facts about our planet.
The Earth is the only planet that is mostly water. Other planets and moons are suspected of having sub-surface water and many have water vapor in their atmosphere, but Earth is the only one with a bounty of liquid water.
Earth’s core helps to protect us from the Sun. The molten core is vital in creating a magnetic field. The magnetic field extends out thousands of kilometers and is referred to as the magnetosphere. The magnetosphere channels the solar wind and the Sun’s radiation around our planet, making it livable.
Earth is the most dense planet in the Solar System. Second in line is Mercury.
As is common knowledge, ours is the only planet known to have life. Several theories abound about Mars, but scientists have proven repeatedly that there are no recognizable life forms on the planet. Many scientists; however, realize that the odds of ours being the only livable planet among the 500 million in our galaxy are remote. They hope that improvements in technology will allow us to find other life in the near future.
The surface area of the Earth makes it about average size for planets within our Solar System. Average is quite acceptable when you look at the harsh conditions elsewhere. For once, it is acceptable to celebrate average
Earth Fact Sheet
![[Global view of Earth]](http://nssdc.gsfc.nasa.gov/planetary/image/earthfact_bg.gif)
Bulk parameters
Mass (1024 kg) 5.9736 Volume (1010 km3) 108.321 Equatorial radius (km) 6378.1 Polar radius (km) 6356.8 Volumetric mean radius (km) 6371.0 Core radius (km) 3485 Ellipticity (Flattening) 0.00335 Mean density (kg/m3) 5515 Surface gravity (m/s2) 9.798 Surface acceleration (m/s2) 9.780 Escape velocity (km/s) 11.186 GM (x 106 km3/s2) 0.3986 Bond albedo 0.306 Visual geometric albedo 0.367 Visual magnitude V(1,0) -3.86 Solar irradiance (W/m2) 1367.6 Black-body temperature (K) 254.3 Topographic range (km) 20 Moment of inertia (I/MR2) 0.3308 J2 (x 10-6) 1082.63 Number of natural satellites 1 Planetary ring system No
Orbital parameters
Semimajor axis (106 km) 149.60 Sidereal orbit period (days) 365.256 Tropical orbit period (days) 365.242 Perihelion (106 km) 147.09 Aphelion (106 km) 152.10 Mean orbital velocity (km/s) 29.78 Max. orbital velocity (km/s) 30.29 Min. orbital velocity (km/s) 29.29 Orbit inclination (deg) 0.000 Orbit eccentricity 0.0167 Sidereal rotation period (hrs) 23.9345 Length of day (hrs) 24.0000 Obliquity to orbit (deg) 23.44
Earth Mean Orbital Elements (J2000)
Semimajor axis (AU) 1.00000011 Orbital eccentricity 0.01671022 Orbital inclination (deg) 0.00005 Longitude of ascending node (deg) -11.26064 Longitude of perihelion (deg) 102.94719 Mean Longitude (deg) 100.46435
North Pole of Rotation
Right Ascension: 0.00 - 0.641T Declination : 90.00 - 0.557T Reference Date : 12:00 UT 1 Jan 2000 (JD 2451545.0) T = Julian centuries from reference date
Terrestrial Magnetosphere
Dipole field strength: 0.3076 gauss-Re3 Latitude/Longitude of dipole N: 78.6 degrees N/70.1 degrees W Dipole offset (planet center to dipole center) distance: 0.0725 Re Latitude/Longitude of offset vector: 18.3 degrees N/147.8 degrees E
Note: Re denotes Earth radii, 6,378 km
Terrestrial Atmosphere
Surface pressure: 1014 mb
Surface density: 1.217 kg/m3
Scale height: 8.5 km
Total mass of atmosphere: 5.1 x 1018 kg
Total mass of hydrosphere: 1.4 x 1021 kg
Average temperature: 288 K (15 C)
Diurnal temperature range: 283 K to 293 K (10 to 20 C)
Wind speeds: 0 to 100 m/s
Mean molecular weight: 28.97 g/mole
Atmospheric composition (by volume, dry air):
Major : 78.08% Nitrogen (N2), 20.95% Oxygen (O2),
Minor (ppm): Argon (Ar) - 9340; Carbon Dioxide (CO2) - 380
Neon (Ne) - 18.18; Helium (He) - 5.24; CH4 - 1.7
Krypton (Kr) - 1.14; Hydrogen (H2) - 0.55
Numbers do not add up to exactly 100% due to roundoff and uncertainty
Water is highly variable, typically makes up about 1%
Moon Fact Sheet
![[Global view of Moon]](http://nssdc.gsfc.nasa.gov/planetary/image/moonfact_bg.gif)
Moon/Earth Comparison
Bulk parameters
Moon Earth Ratio (Moon/Earth) Mass (1024 kg) 0.07349 5.9736 0.0123 Volume (1010 km3) 2.1958 108.321 0.0203 Equatorial radius (km) 1738.1 6378.1 0.2725 Polar radius (km) 1736.0 6356.8 0.2731 Volumetric mean radius (km) 1737.1 6371.0 0.2727 Ellipticity (Flattening) 0.0012 0.00335 0.36 Mean density (kg/m3) 3350 5515 0.607 Surface gravity (m/s2) 1.62 9.80 0.165 Surface acceleration (m/s2) 1.62 9.78 0.166 Escape velocity (km/s) 2.38 11.2 0.213 GM (x 106 km3/s2) 0.0049 0.3986 0.0123 Bond albedo 0.11 0.306 0.360 Visual geometric albedo 0.12 0.367 0.330 Visual magnitude V(1,0) +0.21 -3.86 - Solar irradiance (W/m2) 1367.6 1367.6 1.000 Black-body temperature (K) 270.7 254.3 1.064 Topographic range (km) 16 20 0.800 Moment of inertia (I/MR2) 0.394 0.3308 1.191 J2 (x 10-6) 202.7 1082.63 0.187
Orbital parameters (for orbit about the Earth)
Moon
Semimajor axis (106 km) 0.3844
Perigee (106 km)* 0.3633
Apogee (106 km)* 0.4055
Revolution period (days) 27.3217
Synodic period (days) 29.53
Mean orbital velocity (km/s) 1.023
Max. orbital velocity (km/s) 1.076
Min. orbital velocity (km/s) 0.964
Inclination to ecliptic (deg) 5.145
Inclination to equator (deg) 18.28 - 28.58
Orbit eccentricity 0.0549
Sidereal rotation period (hrs) 655.728
Obliquity to orbit (deg) 6.68
Recession rate from Earth (cm/yr) 3.8
Mean values at opposition from Earth
Distance from Earth (equator, km) 378,000
Apparent diameter (seconds of arc) 1896
Apparent visual magnitude -12.74
* These represent mean apogee and perigee for the lunar orbit.
The orbit changes over the course of the year so the distance
from the Moon to Earth roughly ranges from 357,000 km to 407,000 km.
Lunar Atmosphere
Diurnal temperature range: >100 K to <400 K (roughly -250 F to +250 F)
Total mass of atmosphere: ~25,000 kg
Surface pressure (night): 3 x 10-15 bar (2 x 10-12 torr)
Abundance at surface: 2 x 105 particles/cm3
Estimated Composition (particles per cubic cm):
Helium 4 (4He) - 40,000 ; Neon 20 (20Ne) - 40,000 ; Hydrogen (H2) - 35,000
Argon 40 (40Ar) - 30,000 ; Neon 22 (22Ne) - 5,000 ; Argon 36 (36Ar) - 2,000
Methane - 1000 ; Ammonia - 1000 ; Carbon Dioxide (CO2) - 1000
Trace Oxygen (O+), Aluminum (Al+), Silicon (Si+)
Possible Phosphorus (P+), Sodium (Na+), Magnesium (Mg+)
Composition of the tenuous lunar atmosphere is poorly known and variable,
these are estimates of the upper limits of the nighttime ambient atmosphere
composition. Daytime levels were difficult to measure due to heating and
outgassing of Apollo surface experiments.
For information on the Earth, see the Earth Fact Sheet.
Near Earth Object Fact Sheet
![[Toutatis]](http://nssdc.gsfc.nasa.gov/planetary/image/toutatis_radar.gif)
Information on Selected Near Earth Objects
This list shows selected near Earth objects (NEO's) with close approaches to Earth in the past and predicted to the year 2100, as well as other NEO's of interest. The probability of any of these objects hitting the Earth on these approaches is essentially zero. There are no known NEO's on a collision course with the Earth. There is a possibility that an as yet undiscovered large NEO may hit the Earth, but the probability of this happening over the next 100 years is extremely small. For comparison with the closest approach data, the distance from the Earth to the Moon is about 0.0026 AU (1 AU = 149.6 million km). Closest Closest H Approx. Orbital Semimajor Orbital
Asteroid Approach Approach Abs. Diameter Period Axis Orbital Inclination Number
Number and Name Date (AU) Mag. (meters) (yrs) (AU) Eccentricity (deg) and Name
--------------- ----------- -------- ---- ---------- ------- --------- ------------ ----------- -------------
1937 UB 1937 Oct 30 0.0049 17.1 1250 2.29 1.738 0.649 6.4 1937 UB
1989 UP 1938 Nov 18 0.0052 20.6 330 2.55 1.864 0.473 3.9 1989 UP
2004 UH1 1960 Oct 24 0.0011 28.2 10 0.93 0.954 0.397 3.7 2004 UH1
1999 VP11 1965 Oct 21 0.0022 18.6 820 1.13 1.084 0.584 17.3 1999 VP11
2000 LG6 1971 Jun 3 0.0041 29.0 7 0.88 0.916 0.112 2.8 2000 LG6
2001 AV43 1973 Dec 24 0.0041 24.3 60 1.44 1.277 0.238 0.3 2001 AV43
27002 1998 DV9 1975 Jan 31 0.0045 18.1 1040 2.31 1.745 0.434 8.7 27002 1998 DV9
4581 Asclepius 1989 Mar 22 0.0046 20.5 340 1.03 1.022 0.357 4.9 4581 Asclepius
2003 SW130 1990 Sep 19 0.0015 29.1 7 0.83 0.885 0.304 3.6 2003 SW130
1991 BA 1991 Jan 18 0.0011 28.7 8 3.06 2.105 0.667 2.1 1991 BA
1991 VG 1991 Dec 05 0.0031 28.4 9 1.04 1.027 0.049 1.4 1991 VG
1993 KA2 1993 May 20 0.0010 29.0 7 3.33 2.229 0.770 3.2 1993 KA2
1994 ES1 1994 Mar 15 0.0011 28.6 9 1.68 1.411 0.588 0.9 1994 ES1
1994 XM1 1994 Dec 09 0.00070 28.2 10 2.98 2.068 0.568 4.6 1994 XM1
1995 FF 1995 Mar 27 0.0029 26.4 22 3.54 2.323 0.707 0.6 1995 FF
1996 JA1 1996 May 19 0.0030 21.0 270 4.11 2.565 0.701 22.0 1996 JA1
2000 SG344 1999 May 06 0.0038 24.6 * 0.97 0.980 0.067 0.1 2000 SG344
6489 Golevka 1999 Jun 2 0.0500 19.2 620 3.99 2.514 0.597 2.3 6489 Golevka
2000 LG6 2000 Jun 02 0.0033 29.0 7 0.88 0.916 0.112 2.8 2000 LG6
4486 Mithra 2000 Aug 14 0.0465 15.4 3000 3.26 2.200 0.663 3.0 4486 Mithra
2001 BA16 2001 Jan 15 0.0020 25.8 30 0.91 0.940 0.137 5.8 2001 BA16
1998 WT24 2001 Dec 16 0.0124 17.7 1250 0.61 0.718 0.418 7.4 1998 WT24
4660 Nereus 2002 Jan 22 0.0290 18.3 950 1.82 1.489 0.360 1.4 4660 Nereus
2002 CB26 2002 Feb 08 0.0032 26.5 20 2.73 1.953 0.723 6.8 2002 CB26
2002 EM7 2002 Mar 08 0.0031 24.4 60 0.89 0.921 0.363 1.5 2002 EM7
2002 MN 2002 Jun 14 0.00080 23.3 100 2.44 1.814 0.497 1.0 2002 MN
2002 NY40 2002 Aug 18 0.0035 18.7 780 2.91 2.039 0.710 5.8 2002 NY40
2002 XV90 2002 Dec 11 0.00078 25.2 40 1.99 1.580 0.377 10.0 2002 XV90
1993 KA2 2003 May 20 0.0027 29.0 7 3.33 2.229 0.770 3.2 1993 KA2
1994 PM 2003 Aug 16 0.0250 17.8 1200 1.80 1.479 0.753 18.0 1994 PM
2003 SQ222 2003 Sep 27 0.00056 30.0 4 1.85 1.506 0.519 3.6 2003 SQ222
2003 SW130 2003 Sep 19 0.0011 29.1 7 0.83 0.885 0.304 3.6 2003 SW130
2003 UM3 2003 Oct 12 0.0019 28.0 11 1.61 1.371 0.440 1.5 2003 UM3
2003 XJ7 2003 Dec 6 0.0010 26.3 22 1.39 1.243 0.466 18.2 2003 XJ7
2004 FH 2004 Mar 18 0.00033 26.4 20 0.74 0.818 0.289 0.0 2004 FH
2004 FY15 2004 Mar 27 0.0016 26.1 24 2.52 1.854 0.479 3.5 2004 FY15
2004 FU162 2004 Mar 31 0.00008 28.7 8 0.75 0.827 0.392 4.2 2004 FU162
2004 HE 2004 Apr 18 0.0018 26.8 18 2.36 1.774 0.608 9.5 2004 HE
2004 OD4 2004 Jul 16 0.0011 26.9 17 2.91 2.037 0.515 4.4 2004 OD4
4179 Toutatis 2004 Sep 29 0.0104 15.3 4600 x 2400 1.10 2.511 0.634 0.5 4179 Toutatis
2004 UH1 2004 Oct 24 0.0020 28.2 10 0.93 0.954 0.397 3.7 2004 UH1
2004 YD5 2004 Dec 19 0.0023 29.3 6 3.43 2.273 0.783 3.6 2004 YD5
2005 BS1 2005 Jan 13 0.0018 27.3 15 2.76 1.965 0.567 2.6 2005 BS1
2005 FN 2005 Mar 18 0.00096 26.9 17 0.90 0.934 0.330 3.8 2005 FN
2005 TK50 2005 Oct 10 0.00081 29.1 7 2.66 1.919 0.621 4.9 2005 TK50
2005 UW5 2005 Oct 30 0.0013 27.5 14 1.65 1.398 0.395 2.9 2005 UW5
2005 WN3 2005 Nov 26 0.00056 29.9 4 4.26 2.628 0.740 0.4 2005 WN3
2005 XA8 2005 Dec 5 0.0015 25.6 33 1.70 1.425 0.440 4.8 2005 XA8
2006 BF56 2006 Jan 29 0.0014 29.6 5 3.63 2.363 0.794 1.3 2006 BF56
2004 XP14 2006 Jul 03 0.0029 19.3 595 1.09 1.057 0.157 32.9 2004 XP14
4450 Pan 2008 Feb 19 0.0408 17.2 1570 3.00 1.442 0.587 5.5 4450 Pan
2001 TB 2010 Jan 15 0.0050 24.8 47 2.25 1.716 0.525 4.0 2001 TB
433 Eros 2012 Jan 31 0.1790 11.2 33000 x 13000 1.76 1.458 0.223 10.8 433 Eros
4660 Nereus 2021 Dec 11 0.0263 18.3 950 1.82 1.489 0.360 1.4 4660 Nereus
7482 1994 PC1 2022 Jan 18 0.0132 16.8 1900 1.56 1.346 0.328 33.5 7482 1994 PC1
7335 1989 JA 2022 May 27 0.0269 16.5 2000 2.35 1.770 0.484 15.2 7335 1989 JA
1999 AN10 2027 Aug 7 0.0026 18.0 1100 1.76 1.459 0.562 39.9 1999 AN10
2001 WN5 2028 Jun 26 0.0017 18.2 990 2.24 1.711 0.467 1.9 2001 WN5
2000 SG344 2029 Feb 16 0.0530 24.6 * 0.97 0.980 0.067 0.1 2000 SG344
99942 Apophis 2029 Apr 13 0.00024 19.2 620 0.89 0.922 0.191 3.3 99942 Apophis
1994 VH8 2031 Oct 29 0.0023 27.7 12 2.06 1.616 0.437 3.3 1994 VH8
2005 TA 2034 Oct 04 0.0029 27.2 15 1.45 1.281 0.251 2.8 2005 TA
99942 Apophis 2036 Apr 13 ** 19.2 620 0.89 0.922 0.191 3.3 99942 Apophis
4769 Castalia 2046 Aug 26 0.0251 16.9 1800 x 800 1.10 1.063 0.483 8.9 4769 Castalia
1862 Apollo 2046 Nov 13 0.0353 16.3 1600 1.81 1.471 0.560 6.4 1862 Apollo
4581 Asclepius 2051 Mar 24 0.0122 20.5 340 1.03 1.022 0.357 4.9 4581 Asclepius
1620 Geographos 2051 Aug 23 0.0479 15.6 2000 1.39 1.246 0.335 13.3 1620 Geographos
2004 VZ 2056 Nov 8 0.0041 24.5 54 0.91 0.940 0.244 16.2 2004 VZ
4660 Nereus 2060 Feb 14 0.0080 18.3 940 1.82 1.489 0.360 1.4 4660 Nereus
2000 QX69 2064 Aug 23 0.0025 24.2 63 1.02 1.011 0.271 4.6 2000 QX69
2004 VZ 2066 Nov 8 0.0048 24.5 54 0.91 0.940 0.244 16.2 2004 VZ
2000 SG344 2069 May 2 0.0013 24.6 * 0.97 0.980 0.067 0.1 2000 SG344
2340 Hathor 2069 Oct 21 0.0066 20.3 370 0.78 0.844 0.450 5.8 2340 Hathor
4179 Toutatis 2069 Nov 5 0.0199 15.3 4600 x 2400 3.98 2.511 0.634 0.5 4179 Toutatis
4660 Nereus 2071 Feb 4 0.0157 18.3 940 1.82 1.489 0.360 1.4 4660 Nereus
2005 UW5 2076 Oct 30 0.0031 27.5 14 1.65 1.398 0.395 2.9 2005 UW5
2002 CU11 2080 Aug 31 0.0043 18.3 950 1.35 1.220 0.296 48.8 2002 CU11
1999 SF10 2083 Oct 11 0.0042 24.2 63 1.45 1.278 0.253 1.2 1999 SF10
2340 Hathor 2086 Oct 21 0.0059 20.3 370 0.78 0.844 0.450 5.8 2340 Hathor
2005 VL1 2087 Nov 3 0.0029 26.7 20 0.84 0.891 0.255 0.3 2005 VL1
1566 Icarus 2090 Jun 14 0.0357 16.4 1400 1.12 1.078 0.827 22.9 1566 Icarus
2005 GY8 2092 Sep 23 0.0045 21.2 250 2.90 2.034 0.667 2.8 2005 GY8
2005 YU55 2093 Nov 9 0.0027 22.0 170 1.22 1.141 0.429 0.5 2005 YU55
3200 Phaethon 2093 Dec 14 0.0194 14.6 5000 1.43 1.271 0.890 22.1 3200 Phaethon
2005 AU3 2097 Jan 4 0.0036 26.0 27 1.39 1.247 0.474 3.8 2005 AU3
2000 SG344 2098 May 6 0.0050 24.6 * 0.97 0.980 0.067 0.1 2000 SG344
1036 Ganymed 9.3 32000 4.35 2.665 0.535 26.7 1036 Ganymed
9969 Braille 15.7 1000 x 2200 3.58 2.341 0.434 29.0 9969 Braille
* 2000 SG344 may be an Apollo rocket body in heliocentric orbit
** The orbit of 99942 Apophis will be altered by its close approach to Earth in 2029 and has a chance, estimated at 1 in 6250, of hitting the Earth in 2036.
** The orbit of 99942 Apophis will be altered by its close approach to Earth in 2029 and has a chance, estimated at 1 in 6250, of hitting the Earth in 2036.
433 Eros - Near-Earth asteroid studied by the NEAR mission, which went into orbit in February 2000. (2nd largest NEO)
1036 Ganymed - Largest Near-Earth Object, 32 km in diameter.
1566 Icarus - Highly eccentric Earth-crossing orbit.
1620 Geographos - Scheduled to be visited by Clementine before a computer malfunction cut the mission short.
4179 Toutatis - Double object, probably in contact, one 2.5 km and one 1.5 km diameter (estimated), imaged by Arecibo and Goldstone radar.
4769 Castalia - Double-lobed near-Earth asteroid, each lobe about .75 km diameter. Imaged by Arecibo radar.
9969 Braille - Near-Earth asteroid flown by on 28 July 1999 by the New Millenium Deep Space 1 spacecraft.
1998 SF36 - Near-Earth asteroid target of 2005 orbit and 2007 sample return by the Muses-C spacecraft.
1036 Ganymed - Largest Near-Earth Object, 32 km in diameter.
1566 Icarus - Highly eccentric Earth-crossing orbit.
1620 Geographos - Scheduled to be visited by Clementine before a computer malfunction cut the mission short.
4179 Toutatis - Double object, probably in contact, one 2.5 km and one 1.5 km diameter (estimated), imaged by Arecibo and Goldstone radar.
4769 Castalia - Double-lobed near-Earth asteroid, each lobe about .75 km diameter. Imaged by Arecibo radar.
9969 Braille - Near-Earth asteroid flown by on 28 July 1999 by the New Millenium Deep Space 1 spacecraft.
1998 SF36 - Near-Earth asteroid target of 2005 orbit and 2007 sample return by the Muses-C spacecraft.
Large Terrestrial Impact Craters
~Age ~Diameter Crater Name Location Latitude Longitude (My) (km) --------------- ------------- -------- --------- -------- --------- Vredefort South Africa 27.0 S 27.5 E 2023 300 Sudbury Canada 46.6 N 81.2 W 1850 250 Chicxulub Mexico 21.3 N 89.5 W 65 170 Manicougan Canada 51.4 N 68.7 W 214 100 Popigai Russia 71.7 N 111.7 E 35 100 Chesapeake Bay United States 37.3 N 76.0 W 36 90 Acraman Australia 32.0 S 135.5 E 590 90 Puchezh-Katunki Russia 57.1 N 43.6 E 175 80 Morokweng South Africa 26.5 S 23.5 E 145 70 Kara Russia 69.2 N 65.0 E 73 65 Beaverhead United States 44.6 N 113.0 W 600 60 Tookoonooka Australia 27.1 S 142.8 E 128 55 Charlevoix Canada 47.5 N 70.3 W 357 54 Kara-Kul Tajikstan 39.0 N 73.5 E 5 52 Siljan Sweden 61.0 N 14.9 E 368 52Crater information from The New Solar System, Beatty et al., Cambridge, 1999.
Mars Fact Sheet
![[Global view of Mars]](http://nssdc.gsfc.nasa.gov/image/planetary/mars/marsglobe1.jpg)
Mars/Earth Comparison
Bulk parameters
Mars Earth Ratio (Mars/Earth) Mass (1024 kg) 0.64185 5.9736 0.107 Volume (1010 km3) 16.318 108.321 0.151 Equatorial radius (km) 3396.2 6378.1 0.532 Polar radius (km) 3376.2 6356.8 0.531 Volumetric mean radius (km) 3389.5 6371.0 0.532 Core radius (km) 1700 3485 0.488 Ellipticity (Flattening) 0.00589 0.00335 1.76 Mean density (kg/m3) 3933 5515 0.713 Surface gravity (m/s2) 3.71 9.80 0.379 Surface acceleration (m/s2) 3.69 9.78 0.377 Escape velocity (km/s) 5.03 11.19 0.450 GM (x 106 km3/s2) 0.04283 0.3986 0.107 Bond albedo 0.250 0.306 0.817 Visual geometric albedo 0.170 0.367 0.463 Visual magnitude V(1,0) -1.52 -3.86 - Solar irradiance (W/m2) 589.2 1367.6 0.431 Black-body temperature (K) 210.1 254.3 0.826 Topographic range (km) 30 20 1.500 Moment of inertia (I/MR2) 0.366 0.3308 1.106 J2 (x 10-6) 1960.45 1082.63 1.811 Number of natural satellites 2 1 Planetary ring system No No
Orbital parameters
Mars Earth Ratio (Mars/Earth) Semimajor axis (106 km) 227.92 149.60 1.524 Sidereal orbit period (days) 686.980 365.256 1.881 Tropical orbit period (days) 686.973 365.242 1.881 Perihelion (106 km) 206.62 147.09 1.405 Aphelion (106 km) 249.23 152.10 1.639 Synodic period (days) 779.94 - - Mean orbital velocity (km/s) 24.13 29.78 0.810 Max. orbital velocity (km/s) 26.50 30.29 0.875 Min. orbital velocity (km/s) 21.97 29.29 0.750 Orbit inclination (deg) 1.850 0.000 - Orbit eccentricity 0.0935 0.0167 5.599 Sidereal rotation period (hrs) 24.6229 23.9345 1.029 Length of day (hrs) 24.6597 24.0000 1.027 Obliquity to orbit (deg) 25.19 23.44 1.075
Mars Observational Parameters
Discoverer: Unknown
Discovery Date: Prehistoric
Distance from Earth
Minimum (106 km) 55.7
Maximum (106 km) 401.3
Apparent diameter from Earth
Maximum (seconds of arc) 25.1
Minimum (seconds of arc) 3.5
Mean values at opposition from Earth
Distance from Earth (106 km) 78.39
Apparent diameter (seconds of arc) 17.9
Apparent visual magnitude -2.0
Maximum apparent visual magnitude -2.91
Mars Mean Orbital Elements (J2000)
Semimajor axis (AU) 1.52366231 Orbital eccentricity 0.09341233 Orbital inclination (deg) 1.85061 Longitude of ascending node (deg) 49.57854 Longitude of perihelion (deg) 336.04084 Mean Longitude (deg) 355.45332
North Pole of Rotation
Right Ascension: 317.681 - 0.106T Declination : 52.887 - 0.061T Reference Date : 12:00 UT 1 Jan 2000 (JD 2451545.0) T = Julian centuries from reference date
Martian Atmosphere
Surface pressure: 6.36 mb at mean radius (variable from 4.0 to 8.7 mb depending on season)
[6.9 mb to 9 mb (Viking 1 Lander site)]
Surface density: ~0.020 kg/m3
Scale height: 11.1 km
Total mass of atmosphere: ~2.5 x 1016 kg
Average temperature: ~210 K (-63 C)
Diurnal temperature range: 184 K to 242 K (-89 to -31 C) (Viking 1 Lander site)
Wind speeds: 2-7 m/s (summer), 5-10 m/s (fall), 17-30 m/s (dust storm) (Viking Lander sites)
Mean molecular weight: 43.34 g/mole
Atmospheric composition (by volume):
Major : Carbon Dioxide (CO2) - 95.32% ; Nitrogen (N2) - 2.7%
Argon (Ar) - 1.6%; Oxygen (O2) - 0.13%; Carbon Monoxide (CO) - 0.08%
Minor (ppm): Water (H2O) - 210; Nitrogen Oxide (NO) - 100; Neon (Ne) - 2.5;
Hydrogen-Deuterium-Oxygen (HDO) - 0.85; Krypton (Kr) - 0.3;
Xenon (Xe) - 0.08
Satellites of Mars
Phobos Deimos Semi-major axis* (km) 9378 23459 Sidereal orbit period (days) 0.31891 1.26244 Sidereal rotation period (days) 0.31891 1.26244 Orbital inclination (deg) 1.08 1.79 Orbital eccentricity 0.0151 0.0005 Major axis radius (km) 13.4 7.5 Median axis radius (km) 11.2 6.1 Minor axis radius (km) 9.2 5.2 Mass (1015 kg) 10.6 2.4 Mean density (kg/m3) 1900 1750 Geometric albedo 0.07 0.08 Visual magnitude V(1,0) +11.8 +12.89 Apparent visual magnitude (V0) 11.3 12.40 *Mean orbital distance from the center of Mars.
Asteroid Fact Sheet
![[Gaspra]](http://nssdc.gsfc.nasa.gov/image/planetary/asteroid/gaspra.jpg)
Information on Selected Asteroids
The image above is a false color view of the asteroid 951 Gaspra taken by the Galileo spacecraft. Below is a table of information on selected asteroids, and at the bottom of the page are comments on the asteroids. All of the values for mass and many of the diameter values are only rough estimates.
Asteroid Diameter ~Mass Rotation Orbital Spectral Semimajor Orbital Orbital Number
Number and Name (km) 1015 kg Period Period Class Axis Eccentricity Inclination and Name
--------------- -------- ------- -------- ------- -------- --------- ------------ ----------- --------
1 Ceres 960 x 932 870,000 9.075 hrs 4.60 yrs C 2.767 AU 0.0789 10.58 deg 1 Ceres
2 Pallas 570 x 525 x 482 318,000 7.811 hrs 4.61 yrs U 2.774 AU 0.2299 34.84 deg 2 Pallas
3 Juno 240 20,000 7.210 hrs 4.36 yrs S 2.669 AU 0.2579 12.97 deg 3 Juno
4 Vesta 530 300,000 5.342 hrs 3.63 yrs U 2.362 AU 0.0895 7.14 deg 4 Vesta
45 Eugenia 226 6,100 5.699 hrs 4.49 yrs FC 2.721 AU 0.0831 6.61 deg 45 Eugenia
140 Siwa 103 1,500 18.5 hrs 4.51 yrs C 2.734 AU 0.2157 3.19 deg 140 Siwa
216 Kleopatra 217 x 94 5.385 hrs 4.67 yrs M 2.793 AU 0.2535 13.14 deg 216 Kleopatra
243 Ida 58 x 23 100 4.633 hrs 4.84 yrs S 2.861 AU 0.0451 1.14 deg 243 Ida
253 Mathilde 66 x 48 x 46 103.3 417.7 hrs 4.31 yrs C 2.646 AU 0.2660 6.71 deg 253 Mathilde
433 Eros 33 x 13 x 13 6.69 5.270 hrs 1.76 yrs S 1.458 AU 0.2229 10.83 deg 433 Eros
951 Gaspra 19 x 12 x 11 10 7.042 hrs 3.29 yrs S 2.209 AU 0.1738 4.10 deg 951 Gaspra
1566 Icarus 1.4 0.001 2.273 hrs 1.12 yrs U 1.078 AU 0.8269 22.86 deg 1566 Icarus
1620 Geographos 2.0 0.004 5.222 hrs 1.39 yrs S 1.245 AU 0.3356 13.34 deg 1620 Geographos
1862 Apollo 1.6 0.002 3.063 hrs 1.81 yrs S 1.471 AU 0.5600 6.36 deg 1862 Apollo
2060 Chiron 180 4,000 5.9 hrs 50.7 yrs B 13.633 AU 0.3801 6.94 deg 2060 Chiron
2530 Shipka 5.25 yrs 3.019 AU 0.1237 10.10 deg 2530 Shipka
2703 Rodari 3.25 yrs 2.194 AU 0.0572 6.04 deg 2703 Rodari
3352 McAuliffe 2 - 5 2.57 yrs 1.879 AU 0.3686 4.77 deg 3352 McAuliffe
3840 Mimistrobell 3.38 yrs 2.249 AU 0.0831 3.92 deg 3840 Mimistrobell
4179 Toutatis 4.6 x 2.4 x 1.9 0.05 130. hrs 3.98 yrs S 2.512 AU 0.6339 0.47 deg 4179 Toutatis
4769 Castalia 1.8 x 0.8 0.0005 1.10 yrs 1.063 AU 0.4831 8.89 deg 4769 Castalia
4979 Otawara 5.5 0.2 3.19 yrs 2.168 AU 0.1449 0.91 deg 4979 Otawara
5535 AnneFrank 4.0 3.29 yrs 2.212 AU 0.0643 4.25 deg 5535 AnneFrank
9969 Braille 2.2 x 1.0 3.58 yrs 2.341 AU 0.4336 29.0 deg 9969 Braille
25143 Itokawa ~1 1.52 yrs 1.324 AU 0.2789 1.71 deg 1998 SF36
1 Ceres - The largest and first discovered asteroid, by G. Piazzi on January 1, 1801. Ceres comprises over one-third the 2.3 x 1021 kg estimated total mass of all the asteroids.
2 Pallas - The 2nd largest asteroid and second asteroid discovered, by H. Olbers in 1802.
3 Juno - The 3rd asteroid discovered, by K. Harding in 1804.
4 Vesta - The 3rd largest asteroid, Vesta appears to have a basaltic crust overlying an olivine mantle, indicating differentiation has occurred. Imaged by the Hubble Space Telescope in 1995.
45 Eugenia - Believed to have a small satellite S/1998 (45) 1 in near circular 4.7 day orbit as reported in IAU Circular #7129
140 Siwa - Originally scheduled for July 2008 flyby by the Rosetta spacecraft on its way to Comet P/Wirtanen. The mission has been rerouted.
216 Kleopatra - Imaged by Arecibo radar, shown to have unusual "dog-bone" shape.
243 Ida - Imaged by Galileo on 28 August 1993. These images showed a small satellite, subsequently named Dactyl, in orbit about Ida.
253 Mathilde - Target of NEAR mission flyby on 27 June 1997 en route to 433 Eros.
433 Eros - Near-Earth asteroid being studied from orbit by the NEAR mission, which flew by Eros in February 1999 and went into orbit in February 2000.
951 Gaspra - Imaged by Galileo on 29 Oct 1991.
1566 Icarus - Highly eccentric Earth-crossing orbit.
1620 Geographos - Scheduled to be visited by Clementine before a computer malfunction cut the mission short.
1862 Apollo - Earth-crossing asteroid.
2060 Chiron - Asteroid/Comet (95P/Chiron) in chaotic eccentric orbit near Saturn and Uranus. 14 February 1996 perihelion was the subject of the Chiron Perihelion Campaign.
2530 Shipka - Originally scheduled for October, 2008 flyby by the Rosetta spacecraft on its way to Comet P/Wirtanen. The mission has been rerouted.
2703 Rodari - Originally scheduled for May, 2008 flyby by the Rosetta spacecraft on its way to Comet P/Wirtanen. The mission has been rerouted.
3352 McAuliffe - Amor (Mars-crossing) asteroid originally scheduled for 1999 flyby by the New Millenium Deep Space 1 spacecraft.
3840 Mimistrobell - Originally scheduled for September, 2006 flyby by the Rosetta spacecraft on its way to Comet P/Wirtanen.
4179 Toutatis - Double object, probably in contact, one 2.5 km and one 1.5 km diameter (estimated), imaged by Arecibo and Goldstone radar. Close approach to Earth of this object (about 1.5 million km) will occur on 29 September 2004.
4660 Nereus - Near-Earth asteroid, target of NEAP (Near Earth Asteroid Prospector) rendezvous.
4769 Castalia - Double-lobed near-Earth asteroid, each lobe about .75 km diameter. Imaged by Arecibo radar.
4979 Otawara - Originally scheduled for July 2006 flyby by the Rosetta spacecraft on its way to Comet P/Wirtanen. The mission has been rerouted.
5535 AnneFrank - Target of November 2002 flyby by the Stardust spacecraft on its way to Comet P/Wild 2.
9969 Braille - Near-Earth asteroid target of 28 July 1999 flyby by the Deep Space 1 spacecraft.
25143 Itokawa - (1998 SF36) Near-Earth asteroid target of 2005 orbit and 2007 sample return by the Muses-C spacecraft.
Jupiter Fact Sheet
![[Cassini image of Jupiter]](http://nssdc.gsfc.nasa.gov/planetary/image/jupiter_cassini.jpg)
Jupiter/Earth Comparison
Bulk parameters
Jupiter Earth Ratio (Jupiter/Earth)
Mass (1024 kg) 1,898.6 5.9736 317.83
Volume (1010 km3) 143,128 108.321 1321.33
Radius (1 bar level) (km)
Equatorial 71,492 6,378.1 11.209
Polar 66,854 6,356.8 10.517
Volumetric mean radius (km) 69,911 6,371.0 10.973
Ellipticity 0.06487 0.00335 19.36
Mean density (kg/m3) 1,326 5,515 0.240
Gravity (eq., 1 bar) (m/s2) 24.79 9.80 2.530
Acceleration (eq., 1 bar) (m/s2) 23.12 9.78 2.364
Escape velocity (km/s) 59.5 11.19 5.32
GM (x 106 km3/s2) 126.686 0.3986 317.8
Bond albedo 0.343 0.306 1.12
Visual geometric albedo 0.52 0.367 1.42
Visual magnitude V(1,0) -9.40 -3.86 -
Solar irradiance (W/m2) 50.50 1367.6 0.037
Black-body temperature (K) 110.0 254.3 0.433
Moment of inertia (I/MR2) 0.254 0.3308 0.768
J2 (x 10-6) 14,736 1082.63 13.611
Number of natural satellites 63 1
Planetary ring system Yes No
Orbital parameters
Jupiter Earth Ratio (Jupiter/Earth) Semimajor axis (106 km) 778.57 149.60 5.204 Sidereal orbit period (days) 4,332.589 365.256 11.862 Tropical orbit period (days) 4,330.595 365.242 11.857 Perihelion (106 km) 740.52 147.09 5.034 Aphelion (106 km) 816.62 152.10 5.369 Synodic period (days) 398.88 - - Mean orbital velocity (km/s) 13.07 29.78 0.439 Max. orbital velocity (km/s) 13.72 30.29 0.453 Min. orbital velocity (km/s) 12.44 29.29 0.425 Orbit inclination (deg) 1.304 0.000 - Orbit eccentricity 0.0489 0.0167 2.928 Sidereal rotation period (hours) 9.9250* 23.9345 0.415 Length of day (hrs) 9.9259 24.0000 0.414 Obliquity to orbit (deg) 3.13 23.44 0.134
* System III (1965.0) coordinates
Jupiter Observational Parameters
Discoverer: Unknown
Discovery Date: Prehistoric
Distance from Earth
Minimum (106 km) 588.5
Maximum (106 km) 968.1
Apparent diameter from Earth
Maximum (seconds of arc) 50.1
Minimum (seconds of arc) 29.8
Mean values at opposition from Earth
Distance from Earth (106 km) 628.76
Apparent diameter (seconds of arc) 46.9
Apparent visual magnitude -2.7
Maximum apparent visual magnitude -2.94
Jupiter Mean Orbital Elements (J2000)
Semimajor axis (AU) 5.20336301 Orbital eccentricity 0.04839266 Orbital inclination (deg) 1.30530 Longitude of ascending node (deg) 100.55615 Longitude of perihelion (deg) 14.75385 Mean Longitude (deg) 34.40438
North Pole of Rotation
Right Ascension: 268.05 - 0.009T Declination : 64.49 + 0.003T Reference Date : 12:00 UT 1 Jan 2000 (JD 2451545.0) T = Julian centuries from reference date
Jovian Magnetosphere
Goddard Space Flight Center O4 Model
Dipole field strength: 4.28 gauss-Rj3 Dipole tilt to rotational axis: 9.6 degrees Longitude of tilt: 201.7 degrees Dipole offset (planet center to dipole center) distance: 0.131 Rj Latitude/Longitude of offset vector: -8.0 degrees/148.57 degrees
Note: All latitudes/longitudes are given in Jovian System III (1965.0) coordinates.
Rj denotes Jovian radii, 71,398 km
Rj denotes Jovian radii, 71,398 km
Jovian Atmosphere
Surface Pressure: >>1000 bars
Temperature at 1 bar: 165 K (-108 C)
Temperature at 0.1 bar: 112 K (-161 C)
Density at 1 bar: 0.16 kg/m3
Wind speeds
Up to 150 m/s (<30 degrees latitude)
Up to 40 m/s (>30 degrees latitude)
Scale height: 27 km
Mean molecular weight: 2.22 g/mole
Atmospheric composition (by volume, uncertainty in parentheses)
Major: Molecular hydrogen (H2) - 89.8% (2.0%); Helium (He) - 10.2% (2.0%)
Minor (ppm): Methane (CH4) - 3000 (1000); Ammonia (NH3) - 260 (40);
Hydrogen Deuteride (HD) - 28 (10); Ethane (C2H6) - 5.8 (1.5);
Water (H2O) - 4 (varies with pressure)
Aerosols: Ammonia ice, water ice, ammonia hydrosulfide
Venus Fact Sheet
![[Global view of Venus]](http://nssdc.gsfc.nasa.gov/planetary/image/venus_magellan.jpg)
Venus/Earth Comparison
Bulk parameters
Venus Earth Ratio (Venus/Earth) Mass (1024 kg) 4.8685 5.9736 0.815 Volume (1010 km3) 92.843 108.321 0.857 Equatorial radius (km) 6051.8 6378.1 0.949 Polar radius (km) 6051.8 6356.8 0.952 Volumetric mean radius (km) 6051.8 6371.0 0.950 Ellipticity (Flattening) 0.000 0.00335 0.0 Mean density (kg/m3) 5243 5515 0.951 Surface gravity (eq.) (m/s2) 8.87 9.80 0.905 Surface acceleration (eq.) (m/s2) 8.87 9.78 0.907 Escape velocity (km/s) 10.36 11.19 0.926 GM (x 106 km3/s2) 0.3249 0.3986 0.815 Bond albedo 0.90 0.306 2.94 Visual geometric albedo 0.67 0.367 1.83 Visual magnitude V(1,0) -4.40 -3.86 - Solar irradiance (W/m2) 2613.9 1367.6 1.911 Black-body temperature (K) 184.2 254.3 0.724 Topographic range (km) 15 20 0.750 Moment of inertia (I/MR2) 0.33 0.3308 0.998 J2 (x 10-6) 4.458 1082.63 0.004 Number of natural satellites 0 1 Planetary ring system No No
Orbital parameters
Venus Earth Ratio (Venus/Earth) Semimajor axis (106 km) 108.21 149.60 0.723 Sidereal orbit period (days) 224.701 365.256 0.615 Tropical orbit period (days) 224.695 365.242 0.615 Perihelion (106 km) 107.48 147.09 0.731 Aphelion (106 km) 108.94 152.10 0.716 Synodic period (days) 583.92 - - Mean orbital velocity (km/s) 35.02 29.78 1.176 Max. orbital velocity (km/s) 35.26 30.29 1.164 Min. orbital velocity (km/s) 34.79 29.29 1.188 Orbit inclination (deg) 3.39 0.00 - Orbit eccentricity 0.0067 0.0167 0.401 Sidereal rotation period (hrs) -5832.5 23.9345 243.686 Length of day (hrs) 2802.0 24.0000 116.750 Obliquity to orbit (deg) 177.36 23.44 (0.113)
Venus Observational Parameters
Discoverer: Unknown
Discovery Date: Prehistoric
Distance from Earth
Minimum (106 km) 38.2
Maximum (106 km) 261.0
Apparent diameter from Earth
Maximum (seconds of arc) 66.0
Minimum (seconds of arc) 9.7
Maximum visual magnitude -4.6
Mean values at inferior conjunction with Earth
Distance from Earth (106 km) 41.44
Apparent diameter (seconds of arc) 60.2
Venus Mean Orbital Elements (J2000)
Semimajor axis (AU) 0.72333199 Orbital eccentricity 0.00677323 Orbital inclination (deg) 3.39471 Longitude of ascending node (deg) 76.68069 Longitude of perihelion (deg) 131.53298 Mean Longitude (deg) 181.97973
North Pole of Rotation
Right Ascension: 272.76 Declination : 67.16 Reference Date : 12:00 UT 1 Jan 2000 (JD 2451545.0)
Venus Atmosphere
Surface pressure: 92 bars
Surface density: ~65. kg/m3
Scale height: 15.9 km
Total mass of atmosphere: ~4.8 x 1020 kg
Average temperature: 737 K (464 C)
Diurnal temperature range: ~0
Wind speeds: 0.3 to 1.0 m/s (surface)
Mean molecular weight: 43.45 g/mole
Atmospheric composition (near surface, by volume):
Major: 96.5% Carbon Dioxide (CO2), 3.5% Nitrogen (N2)
Minor (ppm): Sulfur Dioxide (SO2) - 150; Argon (Ar) - 70; Water (H2O) - 20;
Carbon Monoxide (CO) - 17; Helium (He) - 12; Neon (Ne) - 7
Mercury Fact Sheet
![[Global view of Mercury]](http://nssdc.gsfc.nasa.gov/planetary/image/mercuryfact_bg.gif)
Mercury/Earth Comparison
Bulk parameters
Mercury Earth Ratio (Mercury/Earth) Mass (1024 kg) 0.3302 5.9736 0.0553 Volume (1010 km3) 6.083 108.321 0.0562 Equatorial radius (km) 2439.7 6378.1 0.383 Polar radius (km) 2439.7 6356.8 0.384 Volumetric mean radius (km) 2439.7 6371.0 0.383 Ellipticity (Flattening) 0.0000 0.00335 0.000 Mean density (kg/m3) 5427 5515 0.984 Surface gravity (eq.) (m/s2) 3.70 9.80 0.378 Surface acceleration (eq.) (m/s2) 3.70 9.78 0.378 Escape velocity (km/s) 4.3 11.2 0.384 GM (x 106 km3/s2) 0.02203 0.3986 0.0553 Bond albedo 0.068 0.306 0.222 Visual geometric albedo 0.142 0.367 0.387 Visual magnitude V(1,0) -0.42 -3.86 - Solar irradiance (W/m2) 9126.6 1367.6 6.673 Black-body temperature (K) 440.1 254.3 1.731 Moment of inertia (I/MR2) 0.33 0.3308 0.998 J2 (x 10-6) 60. 1082.63 0.055 Number of natural satellites 0 1 Planetary ring system No No
Orbital parameters
Mercury Earth Ratio (Mercury/Earth) Semimajor axis (106 km) 57.91 149.60 0.387 Sidereal orbit period (days) 87.969 365.256 0.241 Tropical orbit period (days) 87.968 365.242 0.241 Perihelion (106 km) 46.00 147.09 0.313 Aphelion (106 km) 69.82 152.10 0.459 Synodic period (days) 115.88 - - Mean orbital velocity (km/s) 47.87 29.78 1.607 Max. orbital velocity (km/s) 58.98 30.29 1.947 Min. orbital velocity (km/s) 38.86 29.29 1.327 Orbit inclination (deg) 7.00 0.00 - Orbit eccentricity 0.2056 0.0167 12.311 Sidereal rotation period (hrs) 1407.6 23.9345 58.785 Length of day (hrs) 4222.6 24.0000 175.942 Obliquity to orbit (deg) ~0 23.44 0.
Mercury Observational Parameters
Discoverer: Unknown
Discovery Date: Prehistoric
Distance from Earth
Minimum (106 km) 77.3
Maximum (106 km) 221.9
Apparent diameter from Earth
Maximum (seconds of arc) 13.
Minimum (seconds of arc) 4.5
Maximum visual magnitude -1.9
Mean values at inferior conjunction with Earth
Distance from Earth (106 km) 91.70
Apparent diameter (seconds of arc) 11.0
Mercury Mean Orbital Elements (J2000)
Semimajor axis (AU) 0.38709893 Orbital eccentricity 0.20563069 Orbital inclination (deg) 7.00487 Longitude of ascending node (deg) 48.33167 Longitude of perihelion (deg) 77.45645 Mean Longitude (deg) 252.25084
North Pole of Rotation
Right Ascension: 281.01 - 0.003T Declination : 61.45 - 0.005T Reference Date : 12:00 UT 1 Jan 2000 (JD 2451545.0) T = Julian centuries from reference date
Mercurian Magnetosphere
Dipole field strength: 0.0033 gauss-Rh3
Dipole tilt to rotational axis: 169 degrees
Longitude of tilt: 285 degrees (from Mercury I flyby)
115 degrees (from Mercury III flyby)
Note: Rh denotes Mercurian radii, 2,439 km
Mercury Atmosphere (Exosphere)
Surface pressure: ~10-15 bar (0.001 picobar) Average temperature: 440 K (167 C) (590-725 K, sunward side) Total mass of atmosphere: <~1000 kg Atmospheric composition: 42% Oxygen (O2), 29% Sodium (Na), 22% Hydrogen (H2), 6% Helium (He), 0.5% Potassium (K), possible trace amounts of Argon (Ar), Carbon Dioxide (CO2), Water (H2O), Nitrogen (N2), Xenon (Xe), Krypton (Kr), Neon (Ne), Calcium (Ca and Ca+), Magnesium (Mg) (The atmosphere of Mercury is essentially a vacuum. Compositional values are variable and not well constrained, values from "Mercury", Vilas, Chapman, and Matthews, eds., University of Arizona Press, 1988)
Sun Fact Sheet
![[Global view of the Sun]](http://nssdc.gsfc.nasa.gov/image/solar/061920se.gif)
Sun/Earth Comparison
Bulk parameters
Sun Earth Ratio (Sun/Earth) Mass (1024 kg) 1,989,100. 5.9736 333,000. GM (x 106 km3/s2) 132,712. 0.3986 333,000. Volume (1012 km3) 1,412,000. 1.083 1,304,000. Volumetric mean radius (km) 696,000. 6371. 109.2 Mean density (kg/m3) 1408. 5515. 0.255 Surface gravity (eq.) (m/s2) 274.0 9.78 28.0 Escape velocity (km/s) 617.6 11.19 55.2 Ellipticity 0.00005 0.0034 0.015 Moment of inertia (I/MR2) 0.059 0.3308 0.178 Visual magnitude V(1,0) -26.74 -3.86 - Absolute magnitude +4.83 Luminosity (1024 J/s) 384.6 Mass conversion rate (106 kg/s) 4300. Mean energy production (10-3 J/kg) 0.1937 Surface emission (106 J/m2s) 63.29 Spectral type G2 V Model values at center of Sun: Central pressure: 2.477 x 1011 bar Central temperature: 1.571 x 107 K Central density: 1.622 x 105 kg/m3
Rotational and Orbital parameters
Sun Earth Ratio (Sun/Earth) Sidereal rotation period (hrs)* 609.12 23.9345 25.449 Obliquity to ecliptic (deg.) 7.25 23.45 0.309 Speed relative to nearby stars (km/s) 19.4
*This is the adopted period at 16 deg. latitude - the actual rotation rate varies with latitude L as:
( 14.37 - 2.33 sin2 L - 1.56 sin4 L ) deg/day
North Pole of Rotation
Right Ascension: 286.13 Declination : 63.87 Reference Date : 1.5 Jan 2000 (JD 2451545.0)
Sun Observational Parameters
Apparent diameter from Earth
At 1 A.U.(seconds of arc) 1919.
Maximum (seconds of arc) 1952.
Minimum (seconds of arc) 1887.
Distance from Earth
Mean (106 km) 149.6
Minimum (106 km) 147.1
Maximum (106 km) 152.1
Solar Magnetic Field
Typical magnetic field strengths for various parts of the Sun Polar Field: 1 - 2 Gauss Sunspots: 3000 Gauss Prominences: 10 - 100 Gauss Chromospheric plages: 200 Gauss Bright chromospheric network: 25 Gauss Ephemeral (unipolar) active regions: 20 Gauss
Solar Atmosphere
Surface Gas Pressure (top of photosphere): 0.868 mb
Effective temperature: 5778 K
Temperature at bottom of photosphere: 6600 K
Temperature at top of photosphere: 4400 K
Temperature at top of chromosphere: ~30,000 K
Photosphere thickness: ~400 km
Chromosphere thickness: ~2500 km
Sun Spot Cycle: 11.4 yr.
Photosphere Composition:
Major elements: H - 90.965%, He - 8.889%
Minor elements (ppm): O - 774, C - 330, Ne - 112, N - 102
Fe - 43, Mg - 35, Si - 32, S - 15
Jupiter Rings Fact Sheet
![[Image of Jupiter's rings]](http://nssdc.gsfc.nasa.gov/planetary/image/jupring.gif)
Rings of Jupiter
Radius Radius/ Optical Albedo Surf. Density
(km) Eq. radius Depth (g/cm2)
Jupiter Equator 71,492 1.000
Halo 100,000 - 122,000 1.40 - 1.71 3 x 10-6
Main 122,000 - 129,000 1.71 - 1.81 5 x 10-6 ~0.015 5 x 10-6
Gossamer (inner) 129,200 - 182,000 1.81 - 2.55 1 x 10-7
Gossamer (outer) 182,000 - 224,900 2.55 - 3.15
Saturn Fact Sheet
![[Voyager 2 image of Saturn]](http://nssdc.gsfc.nasa.gov/planetary/image/saturn_voy2.jpg)
Saturn/Earth Comparison
Bulk parameters
Saturn Earth Ratio (Saturn/Earth)
Mass (1024 kg) 568.46 5.9736 95.159
Volume (1010 km3) 82,713 108.321 763.59
Radius (1 bar level) (km)
Equatorial 60,268 6,378.1 9.449
Polar 54,364 6,356.8 8.552
Volumetric mean radius (km) 58,232 6,371.0 9.140
Ellipticity (Flattening) 0.09796 0.00335 29.24
Mean density (kg/m3) 687 5,515 0.125
Gravity (eq., 1 bar) (m/s2) 10.44 9.80 1.065
Acceleration (eq., 1 bar) (m/s2) 8.96 9.78 0.916
Escape velocity (km/s) 35.5 11.19 3.172
GM (x 106 km3/s2) 37.931 0.3986 95.16
Bond albedo 0.342 0.306 1.12
Visual geometric albedo 0.47 0.367 1.28
Visual magnitude V(1,0) -8.88 -3.86 -
Solar irradiance (W/m2) 14.90 1,367.6 0.011
Black-body temperature (K) 81.1 254.3 0.319
Moment of inertia (I/MR2) 0.210 0.3308 0.635
J2 (x 10-6) 16,298. 1082.63 15.054
Number of natural satellites 62 1
Planetary ring system Yes No
Orbital parameters
Saturn Earth Ratio (Saturn/Earth) Semimajor axis (106 km) 1,433.53 149.60 9.582 Sidereal orbit period (days) 10,759.22 365.256 29.457 Tropical orbit period (days) 10,746.94 365.242 29.424 Perihelion (106 km) 1,352.55 147.09 9.195 Aphelion (106 km) 1,514.50 152.10 9.957 Synodic period (days) 378.09 - - Mean orbital velocity (km/s) 9.69 29.78 0.325 Max. orbital velocity (km/s) 10.18 30.29 0.336 Min. orbital velocity (km/s) 9.09 29.29 0.310 Orbit inclination (deg) 2.485 0.000 - Orbit eccentricity 0.0565 0.0167 3.383 Sidereal rotation period (hours) 10.656* 23.9345 0.445 Length of day (hrs) 10.656 24.0000 0.444 Obliquity to orbit (deg) 26.73 23.44 1.140
* Saturnian System III coordinates
Saturn Observational Parameters
Discoverer: Unknown
Discovery Date: Prehistoric
Distance from Earth
Minimum (106 km) 1195.5
Maximum (106 km) 1658.5
Apparent diameter from Earth
Maximum (seconds of arc) 20.1
Minimum (seconds of arc) 14.5
Mean values at opposition from Earth
Distance from Earth (106 km) 1277.42
Apparent diameter (seconds of arc) 19.5
Apparent visual magnitude 0.7
Maximum apparent visual magnitude 0.43
Saturn Mean Orbital Elements (J2000)
Semimajor axis (AU) 9.53707032 Orbital eccentricity 0.05415060 Orbital inclination (deg) 2.48446 Longitude of ascending node (deg) 113.71504 Longitude of perihelion (deg) 92.43194 Mean Longitude (deg) 49.94432
North Pole of Rotation
Right Ascension: 40.5954 - 0.0577T Declination : 83.5380 - 0.0066T Reference Date : 12:00 UT 1 Jan 2000 (JD 2451545.0) T = Julian centuries from reference date
Saturnian Magnetosphere
Dipole field strength: 0.210 gauss-Rs3 Dipole tilt to rotational axis: < 1 degree Dipole offset (planet center to dipole center) distance: 0.04 to 0.05 Rs northward
Note: Saturn's magnetic field has significant quadrapole and octapole moments, making approximation of the central field as an offset dipole difficult.
Rs denotes Saturnian radii, 60,330 km
Rs denotes Saturnian radii, 60,330 km
Saturnian Atmosphere
Surface Pressure: >>1000 bars
Temperature at 1 bar: 134 K (-139 C)
Temperature at 0.1 bar: 84 K (-189 C)
Density at 1 bar: 0.19 kg/m3
Wind speeds
Up to 400 m/s (<30 degrees latitude)
Up to 150 m/s (>30 degrees latitude)
Scale height: 59.5 km
Mean molecular weight: 2.07 g/mole
Atmospheric composition (by volume, uncertainty in parentheses)
Major: Molecular hydrogen (H2) - 96.3% (2.4%); Helium (He) - 3.25% (2.4%)
Minor (ppm): Methane (CH4) - 4500 (2000); Ammonia (NH3) - 125 (75);
Hydrogen Deuteride (HD) - 110 (58); Ethane (C2H6) - 7 (1.5)
Aerosols: Ammonia ice, water ice, ammonia hydrosulfide
Saturnian Satellite Fact Sheet
![[Montage of Saturn and some of its satellites]](http://nssdc.gsfc.nasa.gov/planetary/image/saturn_sats_2.jpg)
Bulk parameters
Mass Radius Mean density Visual geometric albedo
(1020 kg) (km) (kg/m3)
Major Satellites
Mimas (SI) 0.379 208 x 197 x 191 1150 0.6
Enceladus (SII) 1.08 257 x 251 x 248 1610 1.0
Tethys (SIII) 6.18 538 x 528 x 526 985 0.8
Dione (SIV) 11.0 563 x 561 x 560 1480 0.7
Rhea (SV) 23.1 765 x 763 x 762 1240 0.7
Titan (SVI) 1,345.5 2,575 1880 0.22
Hyperion (SVII) 0.056 180 x 133 x 103 550 0.3
Iapetus (SVIII) 18.1 746 x 746 x 712 1090 0.05 / 0.5
Lesser Satellites
Pan (SXVIII, S/1981 S13) 0.00005 17 x 16 x 10 420 0.5
Daphnis (SXXXV, S/2005 S1) 0.000001 4.3 x 4.1 x 3.2 340
Atlas (SXV, S/1980 S28) 0.00007 20 x 18 x 9 500 0.8
Prometheus (SXVI, S/1980 S27) 0.0016 68 x 40 x 30 480 0.5
Pandora (SXVII, S/1980 S26) 0.0014 52 x 41 x 32 490 0.7
Epimetheus (SXI, S/1980 S3) 0.0053 65 x 57 x 53 640 0.8
Janus (SX, S/1980 S1) 0.0190 102 x 93 x 76 630 0.9
Aegaeon (LIII, S/2008 S1) 0.5
Methone (SXXXII, S/2004 S1) 1.6
Anthe (XLIX, S/2007 S4) ~1
Pallene (SXXXIII, S/2004 S2) 2.9 x 2.8 x 2.0
Calypso (SXIV, S/1980 S25) 0.00004 15 x 12 x 7 1000 1.0
Telesto (SXIII, S/1980 S13) 0.00007 16 x 12 x 10 1000 1.0
Helene (SXII, S/1980 S6) 0.0003 22 x 19 x 13 1300 0.7
Polydeuces (SXXXIV, S/2004 S5) 1.5 x 1.2 x 1.0
Kiviuq (SXXIV, S/2000 S5) ~7 0.06
Ijiraq (SXXII, S/2000 S6) ~5 0.06
Phoebe (SIX) 0.083 109 x 109 x 102 1640 0.08
Paaliaq (SXX, S/2000 S2) ~10 0.06
Skathi (SXXVII, S/2000 S8) ~3 0.06
Albiorix (SXXVI, S/2000 S11) ~13 0.06
Bebhionn (XXXVII, S/2004 S11) ~3
Erriapo (SXXVIII, S/2000 S10) ~4 0.06
Siarnaq (SXXIX, S/2000 S3) ~16 0.06
Skoll (XLVII, S/2006 S8) ~3
Tarvos (SXXI, S/2000 S4) ~7 0.06
Tarqeq (SLII, S/2007 S1) ~3
Greip (SLI, S/2006 S4) ~3
Hyrrokkin (SXLIV, S/2004 S19) ~4
Mundilfari (SXXV, S/2000 S9) ~3 0.06
Jarnsaxa (SL, S/2006 S6) ~3
Narvi (SXXXI, S/2003 S1) ~3 0.06
Bergelmir (XXXVIII, S/2004 S15) ~3
Suttungr (SXXIII, S/2000 S12) ~3 0.06
Hati (XLIII, S/2004 S14) ~3
Bestla (SXXXIX, S/2004 S18) ~3
Farbauti (SXL, S/2004 S9) ~3
Thrymr (SXXX, S/2000 S7) ~3 0.06
Aegir (SXXXVI, S/2004 S10) ~3
Kari (SXLV, S/2006 S2) ~3
Fenrir (SXLI, S/2004 S16) ~2
Surtur (SXLVIII, S/2006 S7) ~3
Loge (SXLVI, S/2006 S5) ~3
Ymir (SXIX, S/2000 S1) ~9 0.06
Fornjot (SXLII, S/2004 S8) ~3
Recently Discovered (Unnamed) Satellites
S/2004 S07 ~3
S/2004 S12 ~3
S/2004 S13 ~3
S/2004 S17 ~2
S/2006 S1 ~3
S/2006 S3 ~3
S/2007 S2 ~3
S/2007 S3 ~3
S/2009 S1 0.3
Orbital parameters
Orbital Rotation
Semimajor axis Period* Period Inclination Eccentricity
(103 km) (Saturnian Radii) (days) (days) (degrees)
Major Satellites
Mimas (SI) 185.52 3.0783 0.9424218 S 1.53 0.0202
Enceladus (SII) 238.02 3.9494 1.370218 S 0.00 0.0045
Tethys (SIII) 294.66 4.8892 1.887802 S 1.86 0.0000
Dione (SIV) 377.40 6.2620 2.736915 S 0.02 0.0022
Rhea (SV) 527.04 8.7449 4.517500 S 0.35 0.0010
Titan (SVI) 1,221.83 20.273 15.945421 S 0.33 0.0292
Hyperion (SVII) 1,481.1 24.575 21.276609 C 0.43 0.1042
Iapetus (SVIII) 3,561.3 59.091 79.330183 S 14.72 0.0283
Lesser Satellites
Pan (SXVIII, S/1981 S13) 133.583 2.2165 0.5750 0.0 0.000
Daphnis (XXXV, S/2005 S1) 136.500 2.26 0.594 0.0 0.000
Atlas (SXV, S/1980 S28) 137.670 2.2820 0.6019 0.3 0.000
Prometheus (SXVI, S/1980 S27) 139.353 2.2843 0.6130 0.0 0.0024
Pandora (SXVII, S/1980 S26) 141.700 2.3512 0.6285 0.0 0.0042
Epimetheus (SXI, S/1980 S3) 151.422 2.5099 0.6942 S 0.34 0.009
Janus (SX, S/1980 S1) 151.472 2.5125 0.6945 S 0.14 0.007
Aegaeon (LIII, S/2008 S1) 167.5 2.78 0.8081 0.001 0.0002
Methone (SXXXII, S/2004 S1) 194 3.22 1.01
Anthe (XLIX, S/2007 S4) 197.7 3.28 1.04 0.1 0.001
Pallene (SXXXIII, S/2004 S2) 211 3.50 1.14
Calypso (SXIV, S/1980 S25) 294.66 4.8892 1.8878 1.473 0.001
Telesto (SXIII, S/1980 S13) 294.66 4.8892 1.8878 1.158 0.001
Helene (SXII, S/1980 S6) 377.40 6.262 2.7369 0.0 0.005
Polydeuces (SXXXIV, S/2004 S5) 377.40 6.26 2.74
Kiviuq (SXXIV, S/2000 S5) 11,110 184. 449 48.7 0.334
Ijiraq (SXXII, S/2000 S6) 11,120 185. 451 49.1 0.316
Phoebe (SIX) 12,944 215. 548R 0.4 174.8 0.164
Paaliaq (SXX, S/2000 S2) 15,200 252. 687 47.2 0.364
Skathi (SXXVII, S/2000 S8) 15,540 258. 728R 148.5 0.270
Albiorix (SXXVI, S/2000 S11) 16,180 268. 783 34.0 0.469
Bebhionn (XXXVII, S/2004 S11) 17,120 284. 835 35.0 0.469
Erriapo (SXXVIII, S/2000 S10) 17,340 288. 871 34.6 0.474
Siarnaq (SXXIX, S/2000 S3) 17,530 291. 896 45.6 0.295
Skoll (XLVII, S/2006 S8) 17,670 293. 878R 161.2 0.464
Tarvos (SXXI, S/2000 S4) 17,980 298. 926 33.8 0.531
Tarqeq (SLII, S/2007 S1) 18,010 299. 888 46.1 0.160
Greip (SLI, S/2006 S4) 18,210 302. 921R 179.8 0.326
Hyrrokkin (SXLIV, S/2004 S19) 18,440 306. 932R 151.4 0.333
Mundilfari (SXXV, S/2000 S9) 18,690 310. 953R 169.4 0.210
Jarnsaxa (SL, S/2006 S6) 18,810 312. 965R 163.3 0.216
Narvi (SXXXI, S/2003 S1) 19,010 315. 1004R 145.8 0.431
Bergelmir (XXXVIII, S/2004 S15) 19,340 321. 1006R 158.5 0.142
Suttungr (SXXIII, S/2000 S12) 19,460 323. 1017R 175.8 0.114
Hati (XLIII, S/2004 S14) 19,860 330. 1039R 165.8 0.372
Bestla (SXXXIX, S/2004 S18) 20,130 334. 1084R 145.2 0.521
Farbauti (SXL, S/2004 S9) 20,390 338. 1086R 156.4 0.206
Thrymr (SXXX, S/2000 S7) 20,470 340. 1094R 175.0 0.470
Aegir (SXXXVI, S/2004 S10) 20,740 344. 1117R 166.7 0.252
Kari (SXLV, S/2006 S2) 22,120 367. 1234R 156.3 0.478
Fenrir (SXLI, S/2004 S16) 22,450 373. 1260R 164.9 0.136
Surtur (SXLVIII, S/2006 S7) 22,710 377. 1298R 177.5 0.451
Ymir (SXIX, S/2000 S1) 23,040 383. 1312R 173.1 0.335
Loge (SXLVI, S/2006 S5) 23,070 383. 1313R 167.9 0.187
Fornjot (SXLII, S/2004 S8) 25,110 417. 1491R 170.4 0.206
Recently Discovered (Unnamed) Satellites
S/2004 S07 21,000 348. 1140R 165.1 0.580
S/2004 S12 19,890 330. 1046R 164.0 0.401
S/2004 S13 18,400 305. 933R 167.4 0.273
S/2004 S17 19,450 323. 986R 166.6 0.259
S/2006 S1 18,980 315. 1015R 154.2 0.130
S/2006 S3 22,100 367. 1227R 150.8 0.471
S/2007 S2 16,730 278. 808R 176.7 0.218
S/2007 S3 18,980 315. 978R 177.2 0.130
S/2009 S1 117 1.94 0.4715 0.0 0.000
*R indicates retrograde motion
S indicates synchronous rotation - the rotation period is the same as the orbital period
C indicates chaotic rotation
Saturnian Rings Fact Sheet
![[Image of Saturn's rings]](http://nssdc.gsfc.nasa.gov/planetary/image/satring.gif)
Rings of Saturn
Radius Radius/ Optical Albedo Thickness Surf. Density Eccentricity
(km) Eq. radius Depth (m) (g/cm2)
Saturn Equator 60,268 1.000
D inner edge 66,900 1.110
D outer edge 74,510 1.236
C inner edge 74,658 1.239 0.05 - 0.10 0.12 - 0.30 5 1.4 - 5
Titan ringlet 77,871 1.292 17 0.00026
Maxwell gap/ringlet 87,491 1.452 17 0.00034
C outer edge 92,000 1.527 0.12 0.2 5 2 - 7
B inner edge 92,000 1.527 0.4 - 2.5 0.4 - 0.6 5 - 10 20 - 100
B outer edge 117,580 1.951 1.8
Cassini division 0.05 - 0.15 0.2 - 0.4 20 18 - 20
A inner edge 122,170 2.027 0.4 - 1.0 0.4 - 0.6 10 - 30 30 - 40
Encke gap 133,589 2.216
Keeler gap 136,530 2.265
A outer edge 136,775 2.269 0.6 0.4 - 0.6 10 - 30 20 - 30
F ring center 140,180 2.326 0.1 0.6 0.0026
G inner edge 170,000 2.82 1.0 x 10-6 105
G outer edge 175,000 2.90
E inner edge 181,000 3 1.5 x 10-5 107
E outer edge 483,000 8 107
Rings, ringlets and gaps radially thinner than 1000 km are listed by center radius.
Uranus Fact Sheet
Uranus/Earth Comparison
Bulk parameters
Uranus Earth Ratio (Uranus/Earth) Mass (1024 kg) 86.832 5.9736 14.536 Volume (1010 km3) 6,833 108.321 63.08 Radius (1 bar level) (km) Equatorial 25,559 6,378.1 4.007 Polar 24,973 6,356.8 3.929 Volumetric mean radius (km) 25,362 6,371.0 3.981 Ellipticity (Flattening) 0.02293 0.00335 6.84 Mean density (kg/m3) 1,270 5,515 0.230 Gravity (eq., 1 bar) (m/s2) 8.87 9.80 0.905 Acceleration (eq., 1 bar) (m/s2) 8.69 9.78 0.889 Escape velocity (km/s) 21.3 11.19 1.903 GM (x 106 km3/s2) 5.794 0.3986 14.536 Bond albedo 0.300 0.306 0.980 Visual geometric albedo 0.51 0.367 1.390 Visual magnitude V(1,0) -7.19 -3.86 - Solar irradiance (W/m2) 3.71 1,367.6 0.0027 Black-body temperature (K) 58.2 254.3 0.229 Moment of inertia (I/MR2) 0.225 0.3308 0.680 J2 (x 10-6) 3343.43 1082.63 3.088 Number of natural satellites 27 1 Planetary ring system Yes No
Orbital parameters
Uranus Earth Ratio (Uranus/Earth) Semimajor axis (106 km) 2,872.46 149.60 19.201 Sidereal orbit period (days) 30,685.4 365.256 84.011 Tropical orbit period (days) 30,588.740 365.242 83.749 Perihelion (106 km) 2,741.30 147.09 18.637 Aphelion (106 km) 3,003.62 152.10 19.748 Synodic period (days) 369.66 - - Mean orbital velocity (km/s) 6.81 29.78 0.229 Max. orbital velocity (km/s) 7.11 30.29 0.235 Min. orbital velocity (km/s) 6.49 29.29 0.222 Orbit inclination (deg) 0.772 0.000 - Orbit eccentricity 0.0457 0.0167 2.737 Sidereal rotation period (hours) -17.24* 23.9345 0.720 Length of day (hrs) 17.24 24.0000 0.718 Obliquity to orbit (deg) 97.77 23.44 4.171* Magnetic coordinates (as determined by the Voyager 2 Radio Science experiment)
Uranus Observational Parameters
Discoverer: William Herschel Discovery Date: 13 March 1781 Distance from Earth Minimum (106 km) 2581.9 Maximum (106 km) 3157.3 Apparent diameter from Earth Maximum (seconds of arc) 4.1 Minimum (seconds of arc) 3.3 Mean values at opposition from Earth Distance from Earth (106 km) 2719.99 Apparent diameter (seconds of arc) 3.9 Apparent visual magnitude 5.5 Maximum apparent visual magnitude 5.32Uranus Mean Orbital Elements (J2000)
Semimajor axis (AU) 19.19126393 Orbital eccentricity 0.04716771 Orbital inclination (deg) 0.76986 Longitude of ascending node (deg) 74.22988 Longitude of perihelion (deg) 170.96424 Mean Longitude (deg) 313.23218
North Pole of Rotation
Right Ascension: 257.43 Declination : -15.10 Reference Date : 12:00 UT 1 Jan 2000 (JD 2451545.0)
Uranian Magnetosphere
Dipole field strength: 0.228 gauss-Ru3 Dipole tilt to rotational axis: 58.6 degrees Dipole offset (planet center to dipole center) distance: 0.3 Ru along the rotation axisNote: Ru denotes Uranian radii, here defined to be 25,600 km
Uranian Atmosphere
Surface Pressure: >>1000 bars Temperature at 1 bar: 76 K (-197 C) Temperature at 0.1 bar: 53 K (-220 C) Density at 1 bar: 0.42 kg/m3 Wind speeds: 0-250 m/s Scale height: 27.7 km Mean molecular weight: 2.64 g/mole Atmospheric composition (by volume, uncertainty in parentheses) Major: Molecular hydrogen (H2) - 82.5% (3.3%); Helium (He) - 15.2% (3.3%) Methane (CH4) - 2.3% Minor (ppm): Hydrogen Deuteride (HD) - 148 Aerosols: Ammonia ice, water ice, ammonia hydrosulfide, methane ice(?)
Uranian Satellite Fact Sheet
Bulk parameters
Mass Radius Mean density Visual geometric albedo (1020 kg) (km) (kg/m3) Major Satellites Miranda (UV) 0.66 240 x 234.2 x 232.9 1,200 0.27 Ariel (UI) 13.5 581.1 x 577.9 x 577.7 1,670 0.35 Umbriel (UII) 11.7 584.7 1,400 0.19 Titania (UIII) 35.2 788.9 1,710 0.28 Oberon (UIV) 30.1 761.4 1,630 0.25 Lesser Satellites Cordelia (UVI, S/1986 U7) 20 0.07 Ophelia (UVII, S/1986 U8) 21 0.07 Bianca (UVIII, S/1986 U9) 26 0.07 Cressida (UIX, S/1986 U3) 40 0.07 Desdemona (UX, S/1986 U6) 32 0.07 Juliet (UXI, S/1986 U2) 47 0.07 Portia (UXII, S/1986 U1) 68 0.07 Rosalind (UXIII, S/1986 U4) 36 0.07 Cupid (S/2003 U2) 5 Belinda (UXIV, S/1986 U5) 40 0.07 Perdita (XXV, S/1986 U10) 10 Puck (UXV, S/1985 U1) 81 0.07 Mab (S/2003 U1) 5 Francisco (XXII, S/2001 U3) 11 Caliban (UXVI, S/1997 U1) 36 0.07 Stephano (UXX, S/1999 U2) 16 0.07 Trinculo (UXXI, S/2001 U1) 9 Sycorax (UXVII, S/1997 U2) 75 0.07 Margaret (UXXIII, S/2003 U3) 10 Prospero (UXVIII, S/1999 U3) 25 0.07 Setebos (UXIX, S/1999 U1) 24 0.07 Ferdinand (XXIV, S/2001 U2) 10
Orbital parameters
Orbital Rotation Semimajor axis Period Period Inclination Eccentricity (103 km) (Uranian Radii) (days) (days) (degrees) Major Satellites Miranda (UV) 129.39 5.078 1.413479 S 4.22 0.0027 Ariel (UI) 191.02 7.481 2.520379 S 0.31 0.0034 Umbriel (UII) 266.30 10.41 4.144177 S 0.36 0.0050 Titania (UIII) 435.91 17.05 8.705872 S 0.14 0.0022 Oberon (UIV) 583.52 22.79 13.463239 S 0.10 0.0008 Lesser Satellites Cordelia (UVI, S/1986 U7) 49.77 1.947 0.335034 0.08 0.0003 Ophelia (UVII, S/1986 U8) 53.79 2.104 0.376400 0.10 0.0099 Bianca (UVIII, S/1986 U9) 59.17 2.315 0.434579 0.19 0.0009 Cressida (UIX, S/1986 U3) 61.78 2.417 0.463570 0.01 0.0004 Desdemona (UX, S/1986 U6) 62.68 2.452 0.473650 0.11 0.0001 Juliet (UXI, S/1986 U2) 64.35 2.518 0.493065 0.07 0.0007 Portia (UXII, S/1986 U1) 66.09 2.586 0.513196 0.06 0.0000 Rosalind (UXIII, S/1986 U4) 69.94 2.736 0.558460 0.28 0.0001 Cupid (S/2003 U2) 74.8 2.93 0.618 Belinda (UXIV, S/1986 U5) 75.26 2.944 0.623527 0.03 0.0001 Perdita (XXV, S/1986 U10) 76.4 2.99 0.638 Puck (UXV, S/1985 U1) 86.01 3.365 0.761833 0.32 0.0001 Mab (S/2003 U1) 97.7 3.82 0.923 Francisco (XXII, S/2001 U3) 4276. 167.3 266.6R 145.2 0.146 Caliban (UXVI, S/1997 U1) 7230. 282.9 579.5R 140.88 0.159 Stephano (UXX, S/1999 U2) 8002. 313.1 676.5R 144.06 0.230 Trinculo (UXXI, S/2001 U1) 8571. 335.3 758.1R 166.33 0.208 Sycorax (UXVII, S/1997 U2) 12179. 476.5 1283.4R 159.40 0.522 Margaret (UXXIII, S/2003 U3) 14345. 561.3 1694.8 56.6 0.661 Prospero (UXVIII, S/1999 U3) 16418. 642.4 1992.8R 151.91 0.443 Setebos (UXIX, S/1999 U1) 17459. 683.1 2202.3R 158.17 0.588 Ferdinand (XXIV, S/2001 U2) 20900. 817.7 2823.4R 169.8 0.368R indicates retrograde motion S indicates synchronous rotation - the rotation period is the same as the orbital period
Uranus Rings Fact Sheet
Rings of Uranus
Radius Radius/ Optical Albedo Width Eccentricity (km) Eq. radius Depth (x10-3) (km) Uranus Equator 25,559 1.000 6 41,837 1.637 ~0.3 ~15 1.5 0.0010 5 42,234 1.652 ~0.5 ~15 ~2 0.0019 4 42,571 1.666 ~0.3 ~15 ~2 0.0011 Alpha 44,718 1.750 ~0.4 ~15 4-10 0.0008 Beta 45,661 1.786 ~0.3 ~15 5-11 0.0004 Eta 47,176 1.834 ~0.4- ~15 1.6 Gamma 47,627 1.863 ~0.3+ ~15 1-4 0.0011 Delta 48,300 1.900 ~0.5 ~15 3-7 0.00004 Lambda 50,024 1.957 ~0.1 ~15 ~2 0. Epsilon 51,149 2.006 0.5-2.3 ~18 20-96 0.0079 A second set of two rings has been discovered at roughly 100,000 km radius.
![[Voyager 2 image of Uranus]](http://nssdc.gsfc.nasa.gov/planetary/image/uranus_voy2.jpg)
![[Image of Uranus and some satellites]](http://nssdc.gsfc.nasa.gov/planetary/image/uranus_sats.jpg)
![[Image of Uranus' rings]](http://nssdc.gsfc.nasa.gov/planetary/image/uranus_rings.jpg)
Neptune Fact Sheet
![[Image of Neptune]](http://nssdc.gsfc.nasa.gov/planetary/image/neptune_voy2.jpg)
Neptune/Earth Comparison
Bulk parameters
Neptune Earth Ratio (Neptune/Earth)
Mass (1024 kg) 102.43 5.9736 17.147
Volume (1010 km3) 6,254 108.321 57.74
Radius (1 bar level) (km)
Equatorial 24,764 6,378.1 3.883
Polar 24,341 6,356.8 3.829
Volumetric mean radius (km) 24,622 6,371.0 3.865
Ellipticity (Flattening) 0.01708 0.00335 5.10
Mean density (kg/m3) 1,638 5,515 0.297
Gravity (eq., 1 bar) (m/s2) 11.15 9.80 1.14
Acceleration (eq., 1 bar) (m/s2) 11.00 9.78 1.12
Escape velocity (km/s) 23.5 11.19 2.10
GM (x 106 km3/s2) 6.8351 0.3986 17.15
Bond albedo 0.290 0.306 0.95
Visual geometric albedo 0.41 0.367 1.12
Visual magnitude V(1,0) -6.87 -3.86 -
Solar irradiance (W/m2) 1.51 1,367.6 0.0011
Black-body temperature (K) 46.6 254.3 0.183
J2 (x 10-6) 3411. 1082.63 3.151
Number of natural satellites 13 1
Planetary ring system Yes No
Orbital parameters
Neptune Earth Ratio (Neptune/Earth) Semimajor axis (106 km) 4,495.06 149.60 30.047 Sidereal orbit period (days) 60,189. 365.256 164.79 Tropical orbit period (days) 59,799.9 365.242 163.73 Perihelion (106 km) 4,444.45 147.09 30.216 Aphelion (106 km) 4,545.67 152.10 29.886 Synodic period (days) 367.49 - - Mean orbital velocity (km/s) 5.43 29.78 0.182 Max. orbital velocity (km/s) 5.50 30.29 0.182 Min. orbital velocity (km/s) 5.37 29.29 0.183 Orbit inclination (deg) 1.769 0.000 - Orbit eccentricity 0.0113 0.0167 0.677 Sidereal rotation period (hours) 16.11* 23.9345 0.673 Length of day (hrs) 16.11 24.0000 0.671 Obliquity to orbit (deg) 28.32 23.44 1.208
* Magnetic coordinates (as determined by the Voyager 2 Radio Science experiment)
Neptune Observational Parameters
Discoverer: Johann Gottfried Galle (based on predictions by
John Couch Adams and Urbain Leverrier)
Discovery Date: 23 September 1846
Distance from Earth
Minimum (106 km) 4305.9
Maximum (106 km) 4687.3
Apparent diameter from Earth
Maximum (seconds of arc) 2.4
Minimum (seconds of arc) 2.2
Mean values at opposition from Earth
Distance from Earth (106 km) 4347.31
Apparent diameter (seconds of arc) 2.3
Apparent visual magnitude 7.8
Maximum apparent visual magnitude 7.78
Neptune Mean Orbital Elements (J2000)
Semimajor axis (AU) 30.06896348 Orbital eccentricity 0.00858587 Orbital inclination (deg) 1.76917 Longitude of ascending node (deg) 131.72169 Longitude of perihelion (deg) 44.97135 Mean Longitude (deg) 304.88003
North Pole of Rotation
Right Ascension: 299.36 + 0.70 sin N Declination : 43.46 - 0.51 cos N Reference Date : 12:00 UT 1 Jan 2000 (JD 2451545.0) N = 359.28 + 549.308T degrees T = Julian centuries from reference date
Neptunian Magnetosphere
Goddard Space Flight Center OTD (O8) ModelDipole field strength: 0.142 gauss-Rn3 Dipole tilt to rotational axis: 46.9 degrees Longitude of tilt: 288 degrees (IAU convention) Dipole offset (planet center to dipole center) distance: 0.55 Rn
Note: Rn denotes Neptunian radii, here defined to be 24,765 km
Neptunian Atmosphere
Surface Pressure: >>1000 bars
Temperature at 1 bar: 72 K (-201 C)
Temperature at 0.1 bar: 55 K (-218 C)
Density at 1 bar: 0.45 kg/m3
Wind speeds: 0-580 m/s
Scale height: 19.1 - 20.3 km
Mean molecular weight: 2.53 - 2.69 g/mole
Atmospheric composition (by volume, uncertainty in parentheses)
Major: Molecular hydrogen (H2) - 80.0% (3.2%); Helium (He) - 19.0% (3.2%);
Methane (CH4) 1.5% (0.5%)
Minor (ppm): Hydrogen Deuteride (HD) - 192; Ethane (C2H6) - 1.5
Aerosols: Ammonia ice, water ice, ammonia hydrosulfide, methane ice(?)
Neptunian Satellite Fact Sheet
Bulk parameters
Mass Radius Mean density Visual geometric albedo (1020 kg) (km) (kg/m3) Naiad (NIII) 0.002 48 x 30 x 26 0.07 Thalassa (NIV) 0.004 54 x 50 x 26 0.09 Despina (NV) 0.02 90 x 74 x 64 0.09 Galatea (NVI) 0.04 102 x 92 x 72 0.08 Larissa (NVII) 0.05 108 x 102 x 84 0.09 Proteus (NVIII) 0.5 220 x 208 x 202 0.10 Triton (NI) 214. 1,353.4 2,050 0.76 Nereid (NII) 0.3 170 0.16 Halimede (NIX, S/2002 N1) 0.001 30 0.16 Sao (NXI, S/2002 N2) 0.001 20 0.16 Laomedeia (NXII, S/2002 N3) 0.001 20 0.16 Neso (NXIII, S/2002 N4) 30 Psamathe (NX, S/2003 N1 0.0002 20 0.16
Orbital parameters
Orbital Rotation Semimajor axis Period* Period Inclination Eccentricity (103 km) (Neptunian Radii) (days) (days) (degrees) Naiad (NIII) 48.227 1.948 0.294396 4.74 0.0003 Thalassa (NIV) 50.075 2.022 0.311485 0.21 0.0002 Despina (NV) 52.526 2.121 0.334655 0.07 0.0001 Galatea (NVI) 61.953 2.502 0.428745 0.05 0.0001 Larissa (NVII) 73.548 2.970 0.554654 0.20 0.0014 Proteus (NVIII) 117.647 4.751 1.122315 0.04 0.0004 Triton (NI) 354.76 14.328 5.876854R S 157.345 0.000016 Nereid (NII) 5,513.4 222.67 360.13619 7.23 0.7512 Halimede (NIX, S/2002 N1) 15730. 635.2 1879.7R 134.1 0.571 Sao (NXI, S/2002 N2) 22420. 905.3 2914.1 48.5 0.293 Laomedeia (NXII, S/2002 N3) 23570. 951.8 3167.9 34.7 0.424 Psamathe (NX, S/2003 N1 46700. 1885.8 9115.9R 137.4 0.450 Neso (NXIII, S/2002 N4) 48390. 1954.0 9374.0R 132.6 0.495*R indicates retrograde motion S indicates synchronous rotation - the rotation period is the same as the orbital period
![[Image of Neptune]](http://nssdc.gsfc.nasa.gov/planetary/image/triton_neptune.jpg)
Neptunian Rings Fact Sheet
Rings of Neptune
Radius Radius/ Optical Albedo Width (km) Eq. radius Depth (x 10-3) (km) Neptune equator 24,766 1.000 Galle (1989N3R) ~41,900 1.692 ~0.00008 ~15 ~2000 LeVerrier (1989N2R) ~53,200 2.148 ~0.002 ~15 ~110 Lassell (1989N4R*) ~53,200 2.148 ~0.00015 ~15 ~4000 Arago (1989N4R*) ~57,200 2.310 <~100 Unnamed (indistinct) 61,950 2.501 Adams (1989N1R) 62,933 2.541 ~0.0045 ~15 ~50 Arcs in Adams Ring: Courage 62,933 2.541 0.12 ~15 Liberté 62,933 2.541 0.12 ~15 Egalité 1 62,933 2.541 0.12 ~40 ~15 Egalité 2 62,933 2.541 0.12 ~40 ~15 Fraternité 62,933 2.541 0.12 ~15 (*Lassell and Arago were originally identified as one ring, designated 1989N4R)
Pluto Fact Sheet
Pluto/Earth Comparison
Bulk parameters
Pluto Earth Ratio (Pluto/Earth) Mass (1024 kg) 0.0125 5.9736 0.0021 Volume (1010 km3) 0.715 108.321 0.0066 Equatorial radius (km) 1195 6378.1 0.187 Polar radius (km) 1195 6356.8 0.188 Volumetric mean radius (km) 1195 6371.0 0.188 Ellipticity (Flattening) 0.0000 0.00335 0.0 Mean density (kg/m3) 1750 5515 0.317 Surface gravity (m/s2) 0.58 9.80 0.059 Surface acceleration (m/s2) 0.58 9.78 0.059 Escape velocity (km/s) 1.2 11.19 0.107 GM (x 106 km3/s2) 0.00083 0.3986 0.0021 Bond albedo 0.4 - 0.6 0.306 1.3 - 2.0 Visual geometric albedo 0.5 - 0.7 0.367 1.4 - 1.9 Visual magnitude V(1,0) -1.0 -3.86 - Solar irradiance (W/m2) 0.89 1367.6 0.0007 Black-body temperature (K) 37.5 254.3 0.147 Number of natural satellites 3* 1 Planetary ring system No No * The two newly discovered moons of Pluto have been named
Comet Fact Sheet
Information on Selected Comets
The image shown is a view of the nucleus of Comet Halley taken by the Giotto spacecraft. Below is a table of information on selected comets, and at the bottom of the page are comments on the comets.Orbital Perihelion Perihelion Semi-Major Orbital Orbital Absolute Number & Name Period Date Distance Axis Eccentricity Inclination Magnitude ------------- ------- ---------- ---------- ---------- ------------ ----------- --------- 1P Halley 76.1 yrs. 1986-02-09 0.587 AU 17.94 AU 0.967 162.2 deg. 5.5 2P Encke 3.30 yrs. 2003-12-28 0.340 AU 2.21 AU 0.847 11.8 deg. 9.8 6P d'Arrest 6.51 yrs. 2008-08-01 1.346 AU 3.49 AU 0.614 19.5 deg. 8.5 9P Tempel 1 5.51 yrs. 2005-07-05 1.500 AU 3.12 AU 0.519 10.5 deg. 12.0 19P Borrelly 6.86 yrs. 2001-09-14 1.358 AU 3.61 AU 0.624 30.3 deg. 11.9 21P Giacobini-Zinner 6.52 yrs. 1998-11-21 0.996 AU 3.52 AU 0.706 31.8 deg. 9.0 26P Grigg-Skjellerup 5.09 yrs. 1992-07-22 0.989 AU 2.96 AU 0.664 21.1 deg. 12.5 27P Crommelin 27.89 yrs. 1984-09-01 0.743 AU 9.20 AU 0.919 29.0 deg. 12.0 45P Honda-Mrkos -Pajdusakova 5.29 yrs. 1995-12-25 0.528 AU 3.02 AU 0.825 4.3 deg. 13.5 46P Wirtanen 5.46 yrs. 2013-10-21 1.063 AU 3.12 AU 0.652 11.7 deg. 9.0 55P Tempel-Tuttle 32.92 yrs. 1998-02-28 0.982 AU 10.33 AU 0.906 162.5 deg. 9.0 67P Churyumov -Gerasimenko 6.57 yrs. 2002-08-18 1.292 AU 3.51 AU 0.632 7.1 deg. 73P Schwassmann 5.36 yrs. 2006-06-02 0.937 AU 3.06 AU 0.694 11.4 deg. 11.7 -Wachmann 3 75P Kohoutek 6.24 yrs. 1973-12-28 1.571 AU 3.4 AU 0.537 5.4 deg. 12.1 76P West-Kohoutek -Ikemura 6.46 yrs. 2000-06-01 1.596 AU 3.45 AU 0.540 30.5 deg. 10.6 81P Wild 2 6.39 yrs. 2003-09-25 1.583 AU 3.44 AU 0.540 3.2 deg. 6.5 95P Chiron 50.7 yrs. 1996-02-14 8.46 AU 13.7 AU 0.383 7 deg. 107P Wilson-Harrington 4.29 yrs. 2001-03-26 1.000 AU 2.64 AU 0.623 2.8 deg. 9.0 Hale-Bopp 4000. yrs. 1997-03-31 0.914 AU 250. AU 0.995 89.4 deg. -1.0 Hyakutake ~40000. yrs. 1996-05-01 0.230 AU ~1165. AU 0.9998 124.9 deg.
Chiron Fact Sheet
Information on Comet 95P/Chiron / Minor Planet (2060) Chiron
Perihelion Date: 14 February 1996, 18:06 UT Perihelion Distance: 8.4639422 AU Date of Perihelion Opposition: 01 April 1996 (closest approach to Earth) Orbital Period: 50.7 years Eccentricity: 0.3831118 Inclination: 6.93540 degrees Semi-Major Axis: ~13.70354 AU Aphelion: ~18.94314 AU Mass: 2 x 1018 to 1019 kg Diameter: 148 to 208 km Rotation Period: ~5.9 hours Asteroid Classification: B-type Discoverer: Charles Kowal Date of Discovery: 01 November 1977 (on a photographic plate taken 18 October)Osculating Orbital Elements
B1950.0 reference frame, Epoch 2450100.5 (17 Jan 1996)Semi-Major Axis: 13.7053530 AU Eccentricity: 0.3831649 Inclination: 6.93524 deg. Longitude of Ascending Node: 208.65735 deg. Longitude of Perihelion: 339.58061 deg. Mean Anomaly: 359.46170 deg.
Notes on the Fact Sheets
Most values listed in the factsheets are from the following sources: IAU/IAG Working Group Report, 2006 Astronomical Almanac, 2000, 2001 Global Earth Physics, American Geophysical Union, 1995 Astrophysical Quantities, C.W. Allen, 1981, 2000 Recent journal articles and personal communications Note that the values listed on the factsheets are not "official" values, there is no single set of agreed upon values. They are based on ongoing research and as such are under study and subject to change at any time. Every effort has been made to present the most up-to-date information, but care should be exercised when using these values.Bulk Parameters
Mass (1024 kg) Mass of the body in 10^24 kilograms Volume (1010 km3) Volume of the body in 10^10 km^3 Equatorial radius (km) Radius of the body at the equator in kilometers Polar radius (km) Radius of the body at the poles in kilometers Volumetric mean radius (km) Radius of a sphere with the same volume as the body Core radius (km) Radius of the planet core in kilometers Ellipticity (Flattening) The ratio (equatorial - polar radius)/(equatorial radius), dimensionless Mean density (kg/m3) Average density of the body (mass/volume) in kilograms/(meter^3) Surface gravity (m/s2) Equatorial gravitational acceleration at the surface of the body or the 1 bar level, not including the effects of rotation, in meters/(second^2) Surface acceleration (m/s2) Effective equatorial gravitational acceleration at the surface of the body or the 1 bar level, including the effects of rotation, in meters/(second^2) Escape velocity (km/s) Initial velocity required to escape the body's gravitational pull in kilometers/second GM (x 106 km3/s2) Gravitational constant times the mass of the body in 10^6 kilometers^3/seconds^2 Visual geometric albedo The ratio of the body's brightness at a phase angle of zero to the brightness of a perfectly diffusing disk with the same position and apparent size, dimensionless. Bond albedo The fraction of incident solar radiation reflected back into space without absorption, dimensionless. Also called planetary albedo. Visual magnitude V(1,0) The visual magnitude of the body if it were one AU (1.496 x 10^8 kilometers) from the Earth at a phase angle of zero, dimensionless. Solar irradiance (W/m2) Solar energy on the body in Watts/(meter^2) Black-body temperature (K) Equivalent black body temperature is the surface temperature the body would have if it were in radiative equilibrium and had no atmosphere, but the same albedo, in Kelvin. Topographic range (km) Difference in elevation between the highest and lowest points on the planet's surface, in kilometers. Moment of inertia (I/MR2) The moment of inertia of the body expressed as the rotational inertia divided by the body's (mass x radius^2). A hollow spherical shell has a moment of inertia of 2/3, a homogeneous sphere 0.4 J2 (x 10-6) The ratio of the difference in the moments of inertia to the mass of the body times the radius^2, (C-A)/(M R^2), x 10^-6, dimensionless Number of natural satellites The number of moons orbiting the planet, as certified by the IAU Absolute magnitude (Comets) The magnitude of the comet at 1 AU for Y = 10, where Y is the photometric parameter giving the observed dependence of the magnitude on heliocentric distance, also designated H(10).
Orbital parameters
Instantaneous values referenced for Julian Date 2451800.5 (13 September 2000) [Astronomical Almanac 2000, p. E3] Semimajor axis (106 km) Mean distance from the Sun (or other central body in the case of satellites) from center to center in 10^6 kilometers Sidereal orbit period (days) The time it takes the body to make one revolution about the Sun relative to the fixed stars in days. Tropical orbit period (days) The average time for the body to make one revolution about the Sun from one point in its seasonal orbit to the equivalent point (e.g. equinox to equinox) in days. For Earth, this equals exactly 1 year. Synodic period (days) The time interval between similar configurations in the orbit (e.g. opposition) of the body and Earth, in days. Perihelion (106 km) The point in a body's orbit closest to the Sun, in 10^6 kilometers. Aphelion (106 km) The point in a body's orbit furthest from the Sun, in 10^6 kilometers. Mean orbital velocity (km/s) The average speed of the body in orbit, in kilometers/second. Max. orbital velocity (km/s) Maximum orbital velocity, at perihelion, in kilometers/second. Min. orbital velocity (km/s) Minimum orbital velocity, at aphelion, in kilometers/second. Orbit inclination (deg) The inclination of the orbit to the ecliptic, in degrees. For satellites, this is with respect to the planet's equator. Orbit eccentricity A measure of the circularity of the orbit, equal to (aphelion - perihelion distance)/(2 x semi-major axis). For the Galilean satellites, the forced eccentricity is given. For a circular orbit eccentricity = 0. Dimensionless. Sidereal rotation period (hrs) The time for one rotation of the body on its axis relative to the fixed stars, in hours. A minus sign indicates retrograde rotation. Length of day (hrs) The average time in hours for the Sun to move from the noon position in the sky at a point on the equator back to the same position, on Earth this defines a 24 hour day. Obliquity to orbit (deg) The tilt of the body's equator relative to the body's orbital plane, in degrees (J2000).
Mean orbital elements
250-year least squares fit elements referenced to J2000 (Global Earth Physics, p. 14) Longitude The point in a body's orbit around the Sun, defined from 0 to 360 degrees. The 0 point of longitude is defined as the first point of Aries. This is the position of the Sun as seen from Earth at Earth's vernal equinox, so at the vernal equinox the Earth is at a longitude of 180 degrees. Longitude of ascending node (deg) The longitude in a body's orbit at which it crosses the ecliptic plane with increasing latitude (i.e. crosses the ecliptic from south to north). Longitude of perihelion (deg) The longitude in a body's orbit at which it reaches the point closest to the Sun. Mean longitude (deg) The longitude a body was at in its orbit at 12:00 Universal (Greenwich) Time on January 1, 2000, also known as J2000 or Julian Day 2451545.0
Atmospheres
Surface Pressure: Atmospheric pressure at the surface, in bars, millibars (mb = 10^-3 bar), or picobars (10^-12 bar). Surface Density: Atmospheric density at the surface in kilograms/meters^3. Scale height: The height interval in which the atmospheric pressure changes by a factor of e = 2.7183 Average temperature: Mean temperature of the body over the entire surface in Kelvin. Diurnal temperature range: Temperature range over an average day in Kelvin. Wind speeds: Near surface wind speeds in meters/second Atmospheric composition: Relative composition by volume of gasses in the atmosphere. Mean molecular weight: Average molecular weight of the atmospheric constituents in grams/mole Atmospheric composition (by volume): Relative volume of constituents in the atmosphere, by percentage or ppm (parts per million).
Related Definitions
Astronomical Unit (AU) - The mean distance from the Sun to the Earth = 149,597,900 km. Bar - A measure of pressure or stress. 1 bar = 10^5 Pascal (Pa) = 10^5 kg m^-1 s^-2 Ecliptic - An imaginary plane defined by the Earth's orbit. Equinox - The point in a body's orbit when the sub-solar point is exactly on the equator. Gravitational Constant - Relates gravitational force to mass, = 6.6726 x 10^-11 meters^3 kilograms^-1 seconds^-2 Opposition - An orbital configuration in which two bodies are on exact opposite sides of the Sun or are on the same side of the Sun forming a line with the Sun (neglecting inclination) Phase Angle - The angle between the Earth and Sun as seen from the body.Sub- and Superscripts
In the explanation of units, we've included a description of the units in the form where, for example, 10^24 equals 10 to the 24 power.
![[Image of Neptune's rings]](http://nssdc.gsfc.nasa.gov/planetary/image/nepring.gif)
![[Hubble image of Pluto and Charon]](http://nssdc.gsfc.nasa.gov/image/planetary/pluto/hst_pluto_charon.jpg)
![[Image of Halley nucleus]](http://nssdc.gsfc.nasa.gov/image/planetary/comet/giotto_halley.jpg)
Planetary Fact Sheet - Metric
| MERCURY | VENUS | EARTH | MOON | MARS | JUPITER | SATURN | URANUS | NEPTUNE | PLUTO | |
| Mass (1024kg) | 0.330 | 4.87 | 5.97 | 0.073 | 0.642 | 1899 | 568 | 86.8 | 102 | 0.0125 |
| Diameter (km) | 4879 | 12,104 | 12,756 | 3475 | 6792 | 142,984 | 120,536 | 51,118 | 49,528 | 2390 |
| Density (kg/m3) | 5427 | 5243 | 5515 | 3340 | 3933 | 1326 | 687 | 1270 | 1638 | 1750 |
| Gravity (m/s2) | 3.7 | 8.9 | 9.8 | 1.6 | 3.7 | 23.1 | 9.0 | 8.7 | 11.0 | 0.6 |
| Escape Velocity (km/s) | 4.3 | 10.4 | 11.2 | 2.4 | 5.0 | 59.5 | 35.5 | 21.3 | 23.5 | 1.1 |
| Rotation Period (hours) | 1407.6 | -5832.5 | 23.9 | 655.7 | 24.6 | 9.9 | 10.7 | -17.2 | 16.1 | -153.3 |
| Length of Day (hours) | 4222.6 | 2802.0 | 24.0 | 708.7 | 24.7 | 9.9 | 10.7 | 17.2 | 16.1 | 153.3 |
| Distance from Sun (106km) | 57.9 | 108.2 | 149.6 | 0.384* | 227.9 | 778.6 | 1433.5 | 2872.5 | 4495.1 | 5870.0 |
| Perihelion (106 km) | 46.0 | 107.5 | 147.1 | 0.363* | 206.6 | 740.5 | 1352.6 | 2741.3 | 4444.5 | 4435.0 |
| Aphelion (106 km) | 69.8 | 108.9 | 152.1 | 0.406* | 249.2 | 816.6 | 1514.5 | 3003.6 | 4545.7 | 7304.3 |
| Orbital Period (days) | 88.0 | 224.7 | 365.2 | 27.3 | 687.0 | 4331 | 10,747 | 30,589 | 59,800 | 90,588 |
| Orbital Velocity (km/s) | 47.9 | 35.0 | 29.8 | 1.0 | 24.1 | 13.1 | 9.7 | 6.8 | 5.4 | 4.7 |
| Orbital Inclination(degrees) | 7.0 | 3.4 | 0.0 | 5.1 | 1.9 | 1.3 | 2.5 | 0.8 | 1.8 | 17.2 |
| Orbital Eccentricity | 0.205 | 0.007 | 0.017 | 0.055 | 0.094 | 0.049 | 0.057 | 0.046 | 0.011 | 0.244 |
| Axial Tilt (degrees) | 0.01 | 177.4 | 23.4 | 6.7 | 25.2 | 3.1 | 26.7 | 97.8 | 28.3 | 122.5 |
| Mean Temperature (C) | 167 | 464 | 15 | -20 | -65 | -110 | -140 | -195 | -200 | -225 |
| Surface Pressure (bars) | 0 | 92 | 1 | 0 | 0.01 | Unknown* | Unknown* | Unknown* | Unknown* | 0 |
| Number of Moons | 0 | 0 | 1 | 0 | 2 | 63 | 62 | 27 | 13 | 3 |
| Ring System? | No | No | No | No | No | Yes | Yes | Yes | Yes | No |
| Global Magnetic Field? | Yes | No | Yes | No | No | Yes | Yes | Yes | Yes | Unknown |
| MERCURY | VENUS | EARTH | MOON | MARS | JUPITER | SATURN | URANUS | NEPTUNE | PLUTO |
Planetary Fact Sheet - U.S. Units
| MERCURY | VENUS | EARTH | MOON | MARS | JUPITER | SATURN | URANUS | NEPTUNE | PLUTO | |
| Mass (1021tons) | 0.364 | 5.37 | 6.58 | 0.081 | 0.708 | 2093 | 627 | 95.7 | 113 | 0.0138 |
| Diameter (miles) | 3032 | 7521 | 7926 | 2159 | 4221 | 88,846 | 74,897 | 31,763 | 30,775 | 1485 |
| Density (lbs/ft3) | 339 | 327 | 344 | 209 | 246 | 83 | 43 | 79 | 102 | 110 |
| Gravity (ft/s2) | 12.1 | 29.1 | 32.1 | 5.3 | 12.1 | 75.9 | 29.4 | 28.5 | 36.0 | 1.9 |
| Escape Velocity (miles/s) | 2.7 | 6.4 | 7.0 | 1.5 | 3.1 | 37.0 | 22.1 | 13.2 | 14.6 | 0.7 |
| Rotation Period (hours) | 1407.6 | -5832.5 | 23.9 | 655.7 | 24.6 | 9.9 | 10.7 | -17.2 | 16.1 | -153.3 |
| Length of Day (hours) | 4222.6 | 2802.0 | 24.0 | 708.7 | 24.7 | 9.9 | 10.7 | 17.2 | 16.1 | 153.3 |
| Distance from Sun (106miles) | 36.0 | 67.2 | 93.0 | 0.239* | 141.6 | 483.8 | 890.8 | 1784.8 | 2793.1 | 3647.2 |
| Perihelion (106 miles) | 28.6 | 66.8 | 91.4 | 0.226* | 128.4 | 460.1 | 840.4 | 1703.4 | 2761.6 | 2755.8 |
| Aphelion (106 miles) | 43.4 | 67.7 | 94.5 | 0.252* | 154.9 | 507.4 | 941.1 | 1866.4 | 2824.5 | 4538.7 |
| Orbital Period (days) | 88.0 | 224.7 | 365.2 | 27.3 | 687.0 | 4331 | 10,747 | 30,589 | 59,800 | 90,588 |
| Orbital Velocity (miles/s) | 29.7 | 21.8 | 18.5 | 0.64 | 15.0 | 8.1 | 6.0 | 4.2 | 3.4 | 2.9 |
| Orbital Inclination(degrees) | 7.0 | 3.4 | 0.0 | 5.1 | 1.9 | 1.3 | 2.5 | 0.8 | 1.8 | 17.2 |
| Orbital Eccentricity | 0.205 | 0.007 | 0.017 | 0.055 | 0.094 | 0.049 | 0.057 | 0.046 | 0.011 | 0.244 |
| Axial Tilt (degrees) | 0.01 | 177.4 | 23.4 | 6.7 | 25.2 | 3.1 | 26.7 | 97.8 | 28.3 | 122.5 |
| Mean Temperature (F) | 333 | 867 | 59 | -4 | -85 | -166 | -220 | -320 | -330 | -375 |
| Surface Pressure(atmospheres) | 0 | 91 | 1 | 0 | 0.01 | Unknown* | Unknown* | Unknown* | Unknown* | 0 |
| Number of Moons | 0 | 0 | 1 | 0 | 2 | 63 | 62 | 27 | 13 | 3 |
| Ring System? | No | No | No | No | No | Yes | Yes | Yes | Yes | No |
| Global Magnetic Field? | Yes | No | Yes | No | No | Yes | Yes | Yes | Yes | Unknown |
| MERCURY | VENUS | EARTH | MOON | MARS | JUPITER | SATURN | URANUS | NEPTUNE | PLUTO |
Planetary Fact Sheet - Ratio to Earth Values
| MERCURY | VENUS | EARTH | MOON | MARS | JUPITER | SATURN | URANUS | NEPTUNE | PLUTO | |
| Mass | 0.0553 | 0.815 | 1 | 0.0123 | 0.107 | 317.8 | 95.2 | 14.5 | 17.1 | 0.0021 |
| Diameter | 0.383 | 0.949 | 1 | 0.2724 | 0.532 | 11.21 | 9.45 | 4.01 | 3.88 | 0.187 |
| Density | 0.984 | 0.951 | 1 | 0.605 | 0.713 | 0.240 | 0.125 | 0.230 | 0.297 | 0.317 |
| Gravity | 0.378 | 0.907 | 1 | 0.166 | 0.377 | 2.36 | 0.916 | 0.889 | 1.12 | 0.059 |
| Escape Velocity | 0.384 | 0.926 | 1 | 0.213 | 0.450 | 5.32 | 3.17 | 1.90 | 2.10 | 0.098 |
| Rotation Period | 58.8 | -244 | 1 | 27.4 | 1.03 | 0.415 | 0.445 | -0.720 | 0.673 | 6.41 |
| Length of Day | 175.9 | 116.8 | 1 | 29.5 | 1.03 | 0.414 | 0.444 | 0.718 | 0.671 | 6.39 |
| Distance from Sun | 0.387 | 0.723 | 1 | 0.00257* | 1.52 | 5.20 | 9.58 | 19.20 | 30.05 | 39.24 |
| Perihelion | 0.313 | 0.731 | 1 | 0.00247* | 1.41 | 5.03 | 9.20 | 18.64 | 30.22 | 30.15 |
| Aphelion | 0.459 | 0.716 | 1 | 0.00267* | 1.64 | 5.37 | 9.96 | 19.75 | 29.89 | 48.02 |
| Orbital Period | 0.241 | 0.615 | 1 | 0.0748 | 1.88 | 11.9 | 29.4 | 83.7 | 163.7 | 248.0 |
| Orbital Velocity | 1.61 | 1.18 | 1 | 0.0344 | 0.810 | 0.439 | 0.325 | 0.229 | 0.182 | 0.158 |
| Orbital Eccentricity | 12.3 | 0.401 | 1 | 3.29 | 5.60 | 2.93 | 3.38 | 2.74 | 0.677 | 14.6 |
| Axial Tilt | 0.0004 | 0.113* | 1 | 0.285 | 1.07 | 0.134 | 1.14 | 4.17* | 1.21 | 2.45* |
| Surface Pressure | 0 | 92 | 1 | 0 | 0.01 | Unknown* | Unknown* | Unknown* | Unknown* | 0 |
| Number of Moons | 0 | 0 | 1 | 0 | 2 | 63 | 62 | 27 | 13 | 3 |
| Ring System? | No | No | No | No | No | Yes | Yes | Yes | Yes | No |
| Global Magnetic Field? | Yes | No | Yes | No | No | Yes | Yes | Yes | Yes | Unknown |
| MERCURY | VENUS | EARTH | MOON | MARS | JUPITER | SATURN | URANUS | NEPTUNE | PLUTO |
