Mercury Crosses a Quiet Sun

Explanation: What's that black dot crossing the Sun? The planet Mercury. Mercury usually passes over or under the Sun , as seen from Earth , but last month the Solar System's innermost planet appeared to go just about straight across the middle . Although witnessed by planet admirers across the globe , a particularly clear view was captured by the Solar Dynamics Observatory (SDO) in Earth orbit . The featured video was captured by the SDO's HMI instrument in a broad range of visible light, and compresses the 5 1/2 hour transit into about 13 seconds. The background Sun was unusually quiet -- even for being near Solar Minimum -- and showed no sunspots . The next solar transit by Mercury will occur in 2032 .