Artist's rendition of an Earth-like exomoon around a giant planet. // NASA/JPL-Caltech
By the last day of the American Astronomical Society meeting in Seattle, attendees can tend to feel all astronomy-ed out. But if you persevered until Thursday, you were gifted with still more great talks and presentations, including a session on habitability. One of my personal favorites was an update by David Kipping on his Hunt for Exomoons with Kepler (HEK). Aside from just being an interesting way to understand when and how moons form, moons around exoplanets could be a huge win for astrobiology. We're still exploring the possibility for oceans and maybe even life on the moons of Jupiter and Saturn. When you think about all the Jupiter-sized exoplanets we've found, with plenty in the habitable zone, the allure of exomoons should become obvious. David has been hard at work for a while, selecting a good sample of Kepler planets to investigate and honing his search algorithms. He now has a program that is amazingly sensitive to digging out signals of exomoons hidden in the Kepler data.
So far, he and his team have analyzed 40 of their list of 400 targets. They haven't found any exomoons yet, and they can rule out satellites down to Ganymede size in the best cases. David told us that he spent most of last year very excited about one planet in particular, Kepler-90g, which showed a highly promising signal. Unfortunately, it turned out to be a very tricky false positive. Never fear. There are still plenty of planets to test. Statistically, David tells us it's still entirely possible for up to a third of planets to harbor moons. We just have to test more planets to know for sure.
Running the searches takes an amazing amount of computing time, which has slowed the work, but the HEK team is getting access to one of NASA's superclusters this year and should be able to churn through 300 of their targets over the coming twelve months. David said 2015 could be the "year of the exomoon." I've got my fingers crossed.