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.
For those who are hoping to find evidence of life somewhere else in the Solar System, there was some exciting news this week. Two moons, Europa and Enceladus, were already thought to be among the best places to search, since both have liquid water oceans beneath their outer icy shells. And now, new data from the Cassini spacecraft and the Hubble Space Telescope has increased the potential for some form of living organisms to be found.
There have been many incredible planetary missions over the past several decades, from as close as our Moon to the outer reaches of the Solar System. Right now, there are robotic explorers at Mars, Jupiter, Saturn, Ceres, and out past Pluto. But there are two more which have travelled even farther, to the most distant fringes of the Solar System, Voyager 1 and Voyager 2. Although they were launched way back in 1977, they are still active today, studying the region where our planetary system “ends” and interstellar space begins. Now, the Hubble Space Telescope is being used to help provide a “road map” for their future paths forward.
Exoplanets are now being discovered by the thousands, but most are so far away that determining anything specific about their composition or atmosphere is currently very difficult. But technology keeps advancing, and scientists are now starting to be able to learn more about them, at least ones which are a bit closer to our own Solar System. One of the most common types of exoplanets are the “super-Earths,” which are larger and more massive than Earth but smaller than Uranus or Neptune. Now, astronomers have been able to analyze the atmosphere of one of these worlds for the first time.
Planetary debris disks, or protoplanetary disks, are some of the most interesting phenomena in astronomy – these giant clouds of dust and gas surrounding young stars are the birthplaces of new planets. Now, astronomers studying one of these disks have found structures never seen before, giant “ripples” which are arch-like or wave-like in appearance.