While the thrill of discovery is what excites the public, there are more fundamental things these new moons can teach us. At Neptune, Showalter was fascinated that his tiny moon discovery in 2013 did not follow the pattern of smallest to largest moons (from the center of Neptune outward) previously discovered in the system. He noted that Neptune's system was completely changed by the capture of Triton (a very large moon) early in the solar system's history, but it's hard to know all the dynamics with the information we have so far.
Other moon mysteries lie in other parts of the solar system. When New Horizons was on its way to Pluto, the moons Styx and Kerberos were found in 2011 and 2012, respectively. Nix was also found in 2005, the year before it launched. (All three finds included researchers part of the "Pluto Companion Search Team", who were tasked specifically for New Horizons' flight.) Previously, only the moon Charon was known - discovered in 1978.
"The Pluto team is intrigued that such a small [dwarf] planet can have such a complex collection of satellites," NASA said in a 2012 statement. "The new discovery provides additional clues for unraveling how the Pluto system formed and evolved. The favored theory is that all the moons are relics of a collision between Pluto and another large Kuiper belt object billions of years ago."
And earlier this year, a moon was found around the dwarf planet Makemake - reinforcing the idea that all dwarf planets have satellites, the team said at the time. The same techniques were used to find Makemake's moon as for the Pluto satellites discovered in 2005, 2011 and 2012. Other searches of Makemake had revealed nothing.
"Our preliminary estimates show that the moon's orbit seems to be edge-on, and that means that often when you look at the system you are going to miss the moon because it gets lost in the bright glare of Makemake," said lead imager Alex Parker, of the Southwest Research Institute in Colorado, in a statement at the time. (Parker did not respond to requests for an interview before this article's deadline.)
A 1986 image of Saturn's rings taken by the Voyager 2 spacecraft, including two moons it found: 1986U7 and 1986U8, now called Cordelia and Orphelia, respectively. Credit: NASA/JPL
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