Basics: Dwarf Planet Pluto
Main Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
Pluto is named after the Greek god of the underworld. It is a called a dwarf planet because it does not clear the area around its orbit. It was originally considered a planet but was reclassified around 2006 (amid much debate). There are still those that dispute the new classification. It is but a classification though.
Pluto is smaller than our own moon, but it has at least 5 moons of its own. One moon, Charon, is the largest moon in comparison to the planet it orbits. At 39 AU from the Sun (39 times the distance of Earth from the Sun), amateur telescopes do not really reveal much at all. 39 is only an average though due to the eccentric orbit. Pluto can be as close as 30 AU and as far away as 49.
The region within which Pluto is located is referred to as the Kuiper Belt. Many of the dwarf planets are found here. As well as the dwarf planets, the area is believed to have a vast amount of small items within it. These include icy and rocky objects, and also quantities of methane and ammonia.
Surface Features and Structure
Due to its distance from the Sun, Pluto is not one of the best observed objects. The fact it is so small does not help either. The closest a probe has come is New Horizons. It did a close up flyby on July 2015. Many exceptional shots were taken of its surface; at the same time certain theories regarding the construction of Pluto were re-evaluated.
Chances of life would be unlikely due to the low temperatures. It is fairly complex with its mountains, valleys, plains and craters. It is also believed that there could be glaciers as well. These may expand and grow with seasonal changes.
It has been suggested Pluto has a subsurface ocean. This would be between the water ice crust and the solid silicate core of Pluto.
Pluto has a somewhat thin atmosphere consisting of various elements: nitrogen, Methane and carbon monoxide. It was noted that it has a blue haze surrounding it; this means it would have blue skies. Like Earth, there is nitrogen in the atmosphere. It would not really be like blue skies on Earth in daytime. It is estimated to be more like a night sky, even with the Sun in the sky. It is so far away that the Sun would truly look like a large star.
Pluto has an atmosphere similar to a comet. When Pluto gets closer to the Sun, the atmosphere expands. As already stated, Pluto can be as close as 30 AU and as far away as 49. As it gets closer to the Sun the surface ice layer goes from solid to gas. Also, due to Pluto’s lower gravity (which is around 6% of Earth’s), the atmosphere is more extended in altitude. It can also snow as the planet moves further away from the Sun.
Pluto has 5 known moons, which is pretty impressive for such a small planetary object. Not only that but it is smaller than Earth’s moon. Its largest (and closest) moon is half the diameter of the planet, and orbits fairly close. It would be an impressive site in the sky, if seen from the surface. It neither rises nor sets, so it is always in the same point with the same side facing the planet.
The rest of the moons are tiny compared to Charon. These are, in order from the closest to furthest: Styx, Nix, Kerberos, and Hydra.
Image of Pluto close up - NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute, Published: December 10, 2015:
NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute, Published: June 9, 2016