Name: DC Whitbeck
What are Pluto's dimensions?
Based on images taken with the repaired Hubble Space Telescope, Pluto has a
diameter of 2320 kilometers (about 3730 miles), to an accuracy of about 1%.
It is thus quite a bit smaller than our Moon, which has a diameter of 3476
km, and much smaller than Earth, which has a diameter of 12,756 km. As you
may know, Earth has a slight equatorial "bulge" (it is not a sphere, but has
an equatorial diameter slightly larger than its polar diameter). Pluto is
probably too small, and rotates too slowly, to have such a bulge so it is
probably almost perfectly spherical. Pluto has a satellite named Charon
which has a diameter of 1270 km. It is pretty astounding that Hubble can
"see" such a small, distant object!
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Update: June 2012