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Just the Pluto/Charon Facts
Click here for tables of the basic facts on Pluto and Charon.
The Family of Planets
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The planets of the solar system are shown in sequence and in relative size (but not to scale in terms of their true separation from one another). Pluto is about 5.5 times smaller than Earth, or about two-thirds the diameter of the Moon. Side by side, Pluto and Charon would barely span the United States. |
| The next-largest objects in Pluto's Kuiper Belt neighborhood are the recently-discovered Quaoar and Sedna, about half of Pluto's size. At the same time, Pluto is much larger than a comet. |
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Pluto's Gravity
A person on Pluto would weigh 1/15 of what they weigh on Earth — a nice way to lose weight, but a chilly way to do it! For comparison, the astronauts walking on the Moon weighed 1/6 of their Earth weight. Click here to see how we figure out Pluto's gravity.
Orientation of Pluto and Charon
Most planets have poles that point roughly up and out of their orbit planes — the exceptions are Uranus and Pluto, which effectively rotate on their sides. Like most satellites, Charon orbits around Pluto's equator.
Click here for a discussion of how this unusual orientation of Pluto and Charon produced mutual eclipses.
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Pluto's Orbit Around the Sun
Pluto's orbit is less circular - more elliptical or "egg-shaped" - than those of the other planets. Pluto's 248-year-long orbit has an eccentricity of 0.25, which means that Pluto's distance from the Sun is as little as 29.7 astronomical units (temporarily bringing it closer than Neptune) and as great as 49.7 astronomical units. For about 20 years in each orbit, Pluto is actually closer to the Sun than Neptune. |
Most of the planets orbit the Sun close to the same plane (called the ecliptic). Pluto's orbit is tilted (by 17.14 degrees) with respect to this plane, the highest inclination of any planet in the solar system. Mercury's inclination is second highest at 7 degrees. The picture below is a "sideways" view, looking at the solar system from the side and a little above the ecliptic plane.
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