How long is a year on Pluto?
(Lansing State Journal, September 16, 1992)

A year is defined as the amount of time it takes the Earth to revolve around the sun.  It takes Pluto about 250 years to complete one revolution about the sun.

This is due to Pluto being about 40 times farther from the sun than Earth is.  This means the gravitational force of the sun on Pluto is also much smaller.  At times, Pluto’s orbit takes it closer to the sun than Neptune, the eighth-farthest planet from the sun.  But for the most of its orbit, Pluto is the farthest planet.

Pluto itself is thought to be made up of icy materials.  It is smaller in size than the moon and has its own satellite, Charon.  It is thought to have a very thin atmosphere containing methane and possibly some heavier gases.  Its mass is 500 times less than Earth’s.  It was discovered in 1930 by Clyde Tombaugh at Lowell Observatory.

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