Timelapse footage of Nicholas U. Mayall 4-meter Telescope observing at night.

This timelapse footage of the Nicholas U. Mayall 4-meter Telescope at the Kitt Peak National Observatory (KPNO), a Program of NSF's NOIRLab. As Earth rotates the bright spiral arm of the Milky appears to move through the dark night sky over the Tohono O'odham Nation Reservation where KPNO is located. The observing dome periodically rotates to allow the telescope to track its target object as it moves throughout the night.