Astronomy Picture of the Day

Explanation: Was Devils Tower once an explosive volcano? Famous for its appearance in films such as Close Encounters, the origin of Devil's Tower in Wyoming, USA is still debated, with a leading hypothesis holding that it is a hardened lava plume that probably never reached the surface to become a volcano. The lighter rock that once surrounded the dense volcanic neck has now eroded away, leaving the dramatic tower. High above, the central band of the Milky Way galaxy arches across the sky. Many notable sky objects are visible, including dark strands of the Pipe Nebula and the reddish Lagoon Nebula to the tower's right. Green grass and trees line the moonlit foreground, while clouds appear near the horizon to the tower's left. Unlike many other international landmarks, mountaineers are permitted to climb Devils Tower.