Exomoons are the wild card in the ongoing chase for habitable worlds.
Astronomers have discovered more than 1,900 exoplanets, a few of which might be friendly to life, but no moons circling these alien bodies have turned up as of yet. Astronomers do not know how common exomoons might be or, for that matter, what they might be like.
The supermassive black hole is 40 million times as massive as the sun and powers a quasar that existed 700 million years after the Big Bang.
The asteroid zoomed by Earth at a perfectly safe distance of around 1.8 million miles (2.9 kilometers).
Images show surprise changes to the spacecraft as it interacted with the atmosphere.
