In the hours before dawn on March 11, 1437, the constellation Scorpio rose over the horizon near Seoul, Korea. Astronomers tasked with scanning the sky and noting nightly changes—aurorae, comets, shooting stars and the like—noticed something odd about the group of stars they called the tail of the dragon, one of the lunar mansions of the night sky.
Long ago, 15 bright radio pulses emerged from a dwarf galaxy about 3 billion light years away from Earth. Last Saturday, a telescope in a remote area of West Virginia picked up those signals from a distant corner of the universe, and yesterday, a group of astronomers and astrophysicists shared preliminary results on their observations.
So dark matter is our frenemy. We have no clue what it is. It's kind of annoying. But we desperately need it in our calculations to arrive at an accurate description of the universe. Scientists are generally uncomfortable whenever we must base our calculations on concepts we don't understand, but we'll do it if we have to. And dark matter is not our first rodeo.
Although the night sky often seems so peaceful and still, a closer look reveals constant movement and change. The Intermediate Palomar Transient Factory (iPTF) in California looks for ephemeral phenomena in the heavens, like stars that fluctuate in brightness, or planets passing in front of their stars.