NASA's Solar Dynamics Observatory, or SDO, has captured the stunning moments of a rare "ring of fire" double eclipse when both Earth and the moon crossed in front of the sun this week.Earth completely eclipsed the sun from SDO's perspective on Thursday just as the moon began its journey across the face of the sun. The end of the Earth eclipse happened just in time for SDO to catch the final stages of the lunar transit, NASA said in a statement on Friday.This particular geometry of Earth, the moon and the sun had effects on viewing down on the ground as well. It resulted in a simultaneous eclipse visible from southern Africa.
The eclipse was what is known as a ring of fire, or annular, eclipse, which is similar to a total solar eclipse, except it happens when the moon is at a point in its orbit farther from Earth than average. The increased distance causes the moon's apparent size to be smaller, so it does not block the entire face of the sun. This leaves a bright, narrow ring of the solar surface visible, looking much like a ring of fire, NASA researchers explained.In the SDO data, one can tell Earth and the moon's shadows apart by their edges.Earth's edge is fuzzy, while the moon's is sharp and distinct. This is because Earth's atmosphere absorbs some of the sun's light, creating an ill-defined edge. On the other hand, the moon has no atmosphere, producing a crisp horizon.