Is It Day or Night at Cerro Tololo?

Don't let the bright sky and the well-lit landscape fool you; this is actually a nighttime video of Cerro Tololo Inter-American Observatory (CTIO). The Moon, seen as the point of light at the far right of the frame, is responsible for illuminating the observatory and the sky above it. Because the Moon can be so bright, astronomers who study the faintest objects schedule their observing runs on moonless nights.

Counterclockwise from the top, we see the DIMM1 Seeing Monitor, the SMARTS 1.0-meter Telescope, the Curtis Schmidt Telescope, the Víctor M. Blanco 4-meter Telescope, the SMARTS 1.5-meter Telescope, and the SMARTS 0.9-meter Telescope.