Pluto
Overview
Pluto was discovered in 1930, and it was named after the Roman god of the underworld. Since then, it was considered the nineth planet of the solar system.
However, after the discovery of similar sized icy worlds in the Kuiper Belt (a region beyond the orbit of Neptune with icy objects), the International Astronomical Union decided, in 2006, to reclassify Pluto a dwarf planet.
Other bodies that are like Pluto, in the Kuiper belt, are Makemake, Eris, Haumea. These bodies are dwarf planets too.
1 Ceres, the largest body in the asteroid belt between Mars and Jupiter, is another dwarf planet.
Interesting Facts
Pluto’s Moons: Pluto has five known moons. Charon is the biggest of the five, and it is almost half the size of Pluto. In fact, Charon and Pluto orbit each other like a double planet system.
Pluto has no ring system around it.
Pluto’s Size: Pluto’s radius is 1,151 kilometers. It is about one-sixth the size of our planet Earth and two-third the size of Earth’s moon. See the picture below that compares the size of Pluto with our planet Earth. Yes, Pluto looks tiny next to our planet Earth.
Pluto’s Orbit: Pluto’s orbit around the Sun is not only very elliptical but also inclined to the ecliptic – the plane on which most of the planets orbit the Sun – by 17 degrees. Pluto orbits the Sun at an average distance of about 5.9 billion kilometers in 248 earth years. Sunlight takes 5.5 hours to travel from the Sun to Pluto.
Sources:
- The Cambridge Guide to the Solar System by Kenneth R. Lang, Cambridge University Press.