The planet formerly known as Pluto has a few companions orbiting it. Because of all the hoopla of the recent classification of Pluto as a dwarf planet, there has been a lot of attention focused around this celestial body. Within the past year, two more satellites have joined an older discovery bringing the number of known celestial objects orbiting Pluto to three.

If you don’t know what a satellite is, at least when it pertains to a celestial body in the solar system, it is an object that orbits a body bigger than itself or a planet. It also cannot be man-made. Many satellites are often moons. In the case of Pluto, the three satellites refer to this dwarf planet’s three moons. They are called Charon, Nix, and Hydra. A man named James Christy, an American astronomer who worked at the United States Naval Observatory at the time, discovered Charon in the late 1970s. Nix and Hydra are fairly new additions to the Pluto companion line-up. The Hubble Telescope captured images of these two moons in May 2005.

Based on beginning observations of Nix and Hydra, scientists believe that they both orbit Pluto in a circular pattern within the same plane as Charon. In addition, scientists think that these two moons were probably formed around the same time period as Charon, possibly in the same event, a cosmic collision that probably occurred several billion years ago. The reasoning behind this hypothesis is that all three moons reflect the light in the same way. In other words, their indistinct color is vastly different from the reddish hue of Pluto. Because Pluto has Charon, Nix and Hydra orbiting it and there is the possibility of even more satellites as well, scientists have compared these celestial bodies to being a mini-solar system all on their own. In fact, scientists have called Pluto and its orbiting moons a Plutonian system. This Plutonian system has a very tight orbit.

Nix and Hydra have longer orbits around Pluto than Charon. In fact, Nix completes almost two orbits to Charon’s twelve orbits around Pluto. Hydra finishes almost three orbits in the same span of time. Quite a few scientists believe that there could be additional moons out there orbiting Pluto. Of course, while scientists formed this theory, they are also a bit confounded that this dwarf planet, which is only about seventy percent of the size of the Earth’s moon, could have all these celestial companions.

Before officially being christened with the names Nix and Hydra, these two newest Plutonian satellites were labeled P1 and P2. Scientists came up with the name Nix after the Greek goddess of the night named Nyx and who just happened to be the mother of Charon, the Greek figure that piloted the boat, which carried souls into the underworld. The name Hydra was derived from the mythological snake with nine heads that guarded the underworld. There is also another influence on the names as well. These two moons start with the letters “N” and “H” which are also the beginning letters of New Horizons, the spacecraft launched in 2005 that is headed towards the area of Pluto.

Scientists have several more years before the spacecraft New Horizons makes its way to the Plutonian system. Until then, they can only speculate about the three moons of dwarf planet Pluto - Charon, Hix and Hydra. The long trip to the Pluto area will help them gather data and bring new views to these satellites.

Photo is in the public domain and was created by NASA

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