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.
Most galaxies in the universe have at least one thing in common: supermassive black holes tend to sit in their centers, silently gorging on interstellar gas and dust and obliterating anything that comes within range of their event horizon. But scientists know very little about the origin of these behemoths or how they got to be so supermassive.