This Is the World’s Largest Digital Camera—and It’s Hunting for Dark Matter

What would you do with the world’s biggest camera? “The major strength of this technology is to see faint objects and the dynamic universe—things that are changing,” says Sandrine Thomas, deputy director of Rubin Observatory Construction. “That gives us a lot of information about the beginning of the universe, galaxies, and objects in our own solar system.” Construction on Rubin—named for the late astronomer Vera Rubin, who pioneered work on dark matter—is set to be completed next year, when it will take its “first photons,” says Thomas, referring to its initial glimpse of the universe. Astronomers like Rachel Mandelbaum at Carnegie Mellon University in Pennsylvania will use Rubin’s galaxy images to study an effect called weak gravitational lensing, where massive objects “distort spacetime and change the paths that light rays would have taken,” she says. “Dark matter doesn’t interact with light, but it has a gravitational effect, so weak lensing is a great way to map out the distribution of dark matter in the universe.” Rubin is particularly well-suited to this technique because of its wide field of view, which makes each snapshot it takes as wide as seven full moons.