How do scientists know what percentages of the universe are made up of dark matter and dark energy? Cosmologist Risa Wechsler of the Kavli Institute for Particle Astrophysics and Cosmology explains. Watch the 3-minute video.

The constraints we deduce from DES SV lensing data (in purple) on the amount of matter in the universe, Ωm, and the amplitude of fluctuations in that matter, σ8. We also show measurements from data from a previous lensing experiment, CFHTLenS (in orange), and the Planck satellite that measures the cosmic microwave background from the early universe (in red), that disagreed with each other. For each data set we show contours that contain 68 percent and 95 percent of the…

Pictured above are many types of galaxies captured by the Dark Energy Camera. At least five are easy to spot: the edge-on spiral on the right side, the pair of colliding spirals at the bottom center, a big spiral in the top-left and an elliptical on the far left.