On October 14, 2023, many people in North and South America craned their heads up to watch an extraordinary celestial spectacle: an annular solar eclipse. The moon moved in front of the sun in such a way that it obscured it except for a narrow halo of rays. Seen from space, the resulting shadow enveloped large parts of North America, as the above image from NASA’s DSCVR (Deep Space Climate Observatory) satellite shows.
However, the annular solar eclipse was only visible in a strip from the US state of Oregon down to Texas, Mexico, Costa Rica and finally Brazil. In the rest of North and South America the sun also darkened, but the sun was only partially obscured – a partial solar eclipse was visible. In both cases, the spectacle only lasted four to six minutes, because the moon’s shadow glides very quickly over the earth’s surface at around 700 meters per second.
A solar eclipse occurs when the new moon moves in front of the sun, partially or even completely covering it. What is crucial for this effect, however, is the perspective we have of the spectacle from Earth. Because the moon’s disk is actually 400 times smaller than that of the sun and could therefore never cover it. Since the moon is 400 times closer to the earth than the sun, the sky looks as if two disks of the same size were superimposed on top of each other.
In the case of the annular solar eclipse over America, the moon was just at the far part of its elliptical orbit. This made it appear a little smaller than usual when viewed from and from the outside and was therefore unable to completely obscure the sun. A glowing wreath remained on the outside. The next annular solar eclipse will not be visible in the United States until June 21, 2039. However, a total solar eclipse is already scheduled for April 8, 2024.