The last decade saw the profound discovery of many worlds beyond our solar system, but none analogs of our home planet Earth. Exploiting precise observational techniques, astronomers inferred the presence of well over two dozen extrasolar planets, most nearly as massive as gas giant Jupiter or more, in close orbits around sun-like stars.

At night, tilting a flashlight up under your chin hides the glowing bulb from the direct view of your friends. Light from the bulb still reflects from your face though, and can give you a startling appearance.

What happens when two of the largest objects in the universe collide? No one was quite sure, but the answer is giving clues to the nature of mysterious dark matter. In the case of MACSJ0025.