Double Eclipse of the Sun

Double Eclipse of the sun

NASA’s Solar Dynamics Observatory (SDO) satellite caught an exceptionally rare sight on September 13, a double eclipse of the sun. The Earth and the moon simultaneously passed across the face of the sun. Back on earth, the residents of Antarctica were treated to a partial solar eclipse at the same time.

Science News explains:

Launched in 2010, SDO studies the sun’s churning atmosphere. Its tilted geosynchronous orbit gives the spacecraft a nearly uninterrupted view, but on rare occasions like this, the Earth or moon can get in the way.

A double eclipse like this is impossible to see from earth. It was only visible because the satellite taking the pictures was outside earth’s orbit, so the earth and moon could appear between it and the sun at the same time.

From the satellite’s perspective, earth passed in front of the sun first, covering it completely and then moving off at the top. Our atmosphere caused the fuzzy edge. As earth finished its transit, the smaller, faster moving moon crossed below it and exited toward the left. Not possessing an atmosphere, the moon produced a sharp edge to its shadow.

An animation here might help make the mechanics of it easier to visualize.

SDO was launched in 2010 into a tilted geosynchronous orbit to study the sun’s turbulent atmosphere; so it has an almost uninterrupted view, but the Earth or moon can occasionally get in the way. A double eclipse like this is extremely rare.


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