Though ancient cultures often saw comets as harbingers of doom, the cosmic "dirty snowballs" are now viewed as important objects that could help scientists learn more about the early evolution of the solar system.
In November 2014, the European Space Agency's Philae probe was dropped from the Rosetta spacecraft, becoming the first human-made spacecraft to soft-land on the surface of a comet. Sending a probe to a comet is one thing. But if astronauts were to land on a comet, what would they experience while living there?
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.
