Moons are exceedingly common in the Solar System – Jupiter alone has 67! But smaller planets do as well of course, except for Mercury and Venus, and even some dwarf planets and asteroids have moons. This includes dwarf planets such as Pluto, which has five moons despite being so small itself. Most of the larger dwarf planets are now known to possess moons, and now another one has been discovered, by the Hubble Space Telescope and two other telescopes, orbiting the third largest known dwarf planet known as 2007 OR10.
Pluto, a tiny frigid world in the distant outskirts of the Solar System, has been full of surprises, as first revealed by the New Horizons spacecraft back in July 2015. Expected to be mostly a cold, geologically dead place, it has instead been shown to be quite the opposite. Yes, it’s bitterly cold of course, but New Horizons found ample evidence that it has also been geologically active in the past and in some ways still is. With tall mountains of solid water ice, ancient riverbeds carved by nitrogen rivers, vast plains, still-flowing glaciers of nitrogen ice, and possible ice volcanoes, Pluto is a wondrous world indeed. Another new finding makes it even more remarkable: evidence for a subsurface ocean of water. This had also been reported on previously by AmericaSpace, but the new update strengthens the case.
To say that the New Horizons mission has been a success would be a massive understatement; this first-ever spacecraft to visit Pluto has revolutionized our understanding of this distant, small world. Pluto and its moons are complex and active places, more so than thought possible by most scientists. Even though New Horizons flew past Pluto instead of orbiting it in July 2015, it still collected an enormous amount of information, which has taken more than a year to be sent back to Earth. That process is now complete, NASA just announced.
It has been 14 months since the New Horizons spacecraft flew past Pluto and its moons, but data still continues to come in, and new discoveries are still being made. The dwarf planet has surprised scientists by its geological activity, for the most part unexpected for such a small, cold body. Now two new results are adding to the mystery of Pluto: the detection of x-rays emanating from the surface and new evidence that Pluto “spray-paints” the north pole of its largest moon Charon a rusty red colour.
Pluto is a tiny world in the outer fringes of the Solar System; for many decades it was only a mere speck of light in even the best telescopes, with only vague hints of surface features. Then, in July 2015, the New Horizons spacecraft flew past Pluto, the first time ever that humanity would get to see this mysterious place up close – and it did not disappoint. An enormous amount of data has continued to be sent back by New Horizons since the flyby, and now five new papers have been published which provide an in-depth overview of the findings so far about Pluto and its moons. Pluto is an active world, with its own unique geology different from anywhere else in the Solar System.