Image: NASA/SDO
The morning of Sept. 1, NASA's Solar Dynamics Observatory (SDO) caught a rare sight: the Earth and Moon, together, blotting out the Sun.As the name implies, SDO exists to spy on the Sun. It does this constantly from its geosynchronous position on the 102° W line of longitude. Because it's geosynchronous—orbiting in sync with Earth, that is, or once every 24ish hours—it experiences an eclipse nightly during its semiannual eclipse seasons when the Sun is briefly hidden behind Earth. On Sept. 1, this occured just as the Moon too passed in between the satellite and its object of affection. At the same time, an annular "ring-of-fire" eclipse was visible in southern Africa.In the video, you can discern the two objects by their edges (and scale). Earth, as it passes in front of the Sun, has a fuzzy edge, owing to its thick atmosphere. With little between its surface and space, the Moon has a sharply defined edge.