Aurora & Comet Ikeya-Zhang

Bright display of aurora borealis is photographed with the bright comet of 2002, Ikeya-Zhang (on the lower left). At the very center an elongated hazy smudge known as M31, the Great Andromeda Galaxy, is also visible. From the photographer: “This dramatic type-A aurora appears to cascade in the northwestern sky over the moonlit snow near Wickersham Dome, White Mountains National Recreation Area of Alaska, on the night of March 20/21, 2002. This curtain of color extends vertically through the atmosphere; its nearly vertical rays trace out the Earth’s magnetic field lines and point toward the magnetic zenith. The dull red light is created by glowing oxygen more than 120 miles (200 km) above our planet’s surface, while the green originates much lower―only about 60 miles (100 km) up. The purple originates with nitrogen.”