Astronomers have discovered the telltale signature of a supermassive black hole that recently tore a star apart that came too close. This is known as a tidal disruption event, and it causes a flash of X-ray radiation that's detectable from our space telescopes. The expanding debris cloud from the shredded star has drifted into the path of another star, which is now repeatedly crashing through the cloud every 48 hours, sending out additional flares.

We've learned a tremendous amount about Mars because samples from the Red Planet have already been delivered to Earth: meteorites. Scientists have studied the composition of Martian meteorites and tracked down the specific craters on Mars where many of them came from. It's believed that Mars has been struck hard enough to produce meteorites about ten times in recent history. Some of these craters have yet to be matched with meteorites, but the rocks could be out there.