Pluto is more like a moon.

... or, rather, two moons.

Pluto and Charon as seen by the Hubble Space Telescope.

Pluto's mass is only 0.002 Earth masses and its radius is about 0.2 RE, or abut 2/3 the radius of the earth's moon. This gives it a density of about 2000 kg/m3, suggesting that it is made of ice and rock.

Its moon, Charon, has a radius about half that of Pluto.

ASTR 121 Home
Davison E. Soper, Institute of Theoretical Science, University of Oregon, Eugene OR 97403 USA