What is a solar eclipse?
An illustration of a total solar eclipse. Image credit: NASA/GSFC/CI Lab
On Earth, a total solar eclipse means that for just a few minutes, the sky goes dark. But what does a total solar eclipse look like from space?
What Exactly is a Solar Eclipse?
A solar eclipse happens when, at just the right moment, the moon comes between the sun and Earth. When the moon only blocks out part of the sun’s light, it’s called a partial solar eclipse. Sometimes, the moon blocks all of the sun’s light. This is called a total solar eclipse.
Seeing the Moon’s Shadow
As the moon passes in front of the sun’s light, it casts a shadow on part of the Earth—and Earth-observing satellites can see this shadow. Watch the short video clip below to see a satellite’s view of the moon’s shadow on Earth during a solar eclipse.
This video of a solar eclipse over the Pacific Ocean was captured by Himawari-8, a Japanese weather satellite. Satellites have the unique opportunity to watch the moon’s shadow move across the surface of Earth during an eclipse! Credit: CIMSS Satellite Blog YouTube Channel
As you can see in the video above, the moon’s shadow moves as the Earth rotates. The shadow traces a path across the Earth. This path is called the path of totality. If you want to experience total darkness during an eclipse, you have to be right in this path of the moon’s shadow.
Caution!
Eye Safety During a Total Solar Eclipse
Except during the brief total phase of a total solar eclipse, when the Moon completely blocks the Sun’s bright face, it is not safe to look directly at the Sun without specialized eye protection for solar viewing.
For safety information, visit the NASA Eclipse Safety Page.
Watching the Moon Pass in Front of the Sun
Total solar eclipses also provide a rare chance to see the sun’s atmosphere, called the corona. The corona is very dim, and it’s usually hard to see because the sun is so much brighter. However, during those few minutes of a total solar eclipse, all you can see is the light from the corona!
Some satellites that observe the sun can also get a special glimpse during a total solar eclipse. They can actually watch the sun as the moon passes over it. Watch the short video clip below to see a satellite’s view of the moon eclipsing the sun.
Watch the moon passing in front of the sun in this video captured by the Japanese spacecraft Hinode and its X-Ray Telescope instrument. Credit: NASA's Marshall Center YouTube Channel
GOES-16 Watches Earth and the Sun
On August 21, 2017 all of North America was at least partially in the path of a solar eclipse. And, anyone lucky enough to be in the path of totality—which stretched from Salem, Oregon to Charleston, South Carolina—at that time was able to see a total solar eclipse.
The GOES-16 weather satellite was watching that day, too! GOES-16 has an instrument that allowed it to capture views of Earth during this solar eclipse.
The Advanced Baseline Imager, or ABI, keeps an eye on Earth. On an ordinary day, it helps scientists spot severe weather on Earth and other hazards like forest fires. During a solar eclipse, it can watch the moon’s shadow pass over the Earth!
Follow the moon's shadow as it moves West to East across the Northern Hemisphere during the August 21, 2017 total solar eclipse! This geocolor animation was created with images from GOES-16's ABI instrument. Credit: CIRA