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Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

See Explanation. Clicking on the picture will download the highest resolution version available.

A Seemingly Square Sun

Explanation: Isn't the Sun round? Yes, but in the above picture, the Earth's atmosphere makes it appear almost square. Here a layer of air near the Earth was so warm it acted like a giant lens , creating increasingly distorted paths for sunlight to reach the camera. Similarly, on a long flat highway, it may appear that the road in the distance is covered with water. In this case, light from the blue sky is being unusually refracted by warm air just above the dry road. No matter how the Earth's atmosphere makes the Sun appear, the Sun will always be spherical. This setting Sun was photographed over Lake Michigan in Muskegon , MI.

Date May 26, 1998
Credit Credit & Copyright: T. Polakis
Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
A service of: ASD at NASA / GSFC,
NASA Science Activation & Michigan Tech. U.