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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.

Sun Pillar with Upper Tangent Arc

Explanation: This was not a typical sun pillar. Just after sunrise two weeks ago in Providence , Rhode Island , USA , a photographer, looking out his window, was suddenly awestruck. The astonishment was caused by a sun pillar that fanned out at the top. Sun pillars, singular columns of light going up from the Sun , are themselves rare to see, and are known to be caused by sunlight reflecting from wobbling, hexagon-shaped ice-disks falling through Earth's atmosphere . Separately, upper tangent arcs are known to be caused by sunlight refracting through falling hexagon-shaped ice-tubes . Finding a sun pillar connected to an upper tangent arc is extraordinary, and, initially, took some analysis to figure out what was going on. A leading theory is that this sun pillar was also created, in a complex and unusual way, by falling ice tubes. Few might believe that such a rare phenomenon was seen again if it wasn't for the quick thinking of the photographer -- and the camera on his nearby smartphone .

News from Mars: NASA Perseverance Coverage

Date February 17, 2021
Credit Image Credit & Copyright: Mike Cohea
Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
A service of: ASD at NASA / GSFC,
NASA Science Activation & Michigan Tech. U.