Astronomers believe they may have the first-ever detection of an exomoon. An exomoon (extra-solar moon) is a moon orbiting an exoplanet (extra-solar planet — a planet orbiting a star other than our Sun). The detection was made using a technique called microlensing, in which a closer star passes in front of a star that’s further away, temporarily brightening the background star and allowing astronomers to study it more closely. These are once-in-a-lifetime events that last about a month. Astronomers detect them by observing lots and lots of stars and hoping to catch one by chance.

Scientists have modeled a scenario in which a giant asteroid — one that’s four times larger than the asteroid that wiped out the dinosaurs — impacted the Earth billions of years ago and found that such an asteroid could have set the continents in motion. There is evidence of such an asteroid in the form of tiny rocks in South Africa that would be the only remnants of the giant impactor.

In other asteroid news, NASA is planning to send a spacecraft to an asteroid to collect samples. The OSIRIS-Rex mission is scheduled to launch in the fall of 2016, and will rendezvous with asteroid 1999 RQ36 (aka “Bennu”) in 2018, but won’t return with samples until the year 2023. Why would anyone want to do this? Well, there is some speculation that water and other materials necessary for life on Earth were deposited here by asteroids billions of years ago. This can be tested by sampling the mineral make-up of a relatively nearby asteroid.