ISS Crosses Sun in 8-Frame Eclipse Composite During Aug. 12 Total Solar Eclipse

Q: How did astronauts aboard the ISS miss totality while Earth-bound observers watched the sun completely vanish just days ago?

They missed totality because the ISS was simply in the wrong place to enter the Moon’s tiny central shadow. A total solar eclipse is only total inside the narrow path of the umbra, the darkest part of the Moon’s shadow, which was about 180 miles wide as it raced across parts of Greenland, Iceland, Spain, Russia and the North Atlantic on Aug. 12. The space station, orbiting about 420 kilometers above Earth and circling the planet every roughly 92 minutes, was not aligned with that shadow cone at the right time. From the ISS, astronauts were viewing the event from a completely different geometry than people on the ground. Jessica Meir said the crew saw only a partial eclipse, with about 18% of the Sun covered. That means the station was in the penumbra, the much broader outer shadow where the Moon blocks only part of the Sun, not in the umbra where totality occurs. Being “between Earth and the Moon” does not guarantee totality. The Moon’s shadow narrows as it reaches Earth, and totality depends on an observer’s exact position in three-dimensional space at a precise moment. A shift of even hundreds of kilometers can mean the difference between a blacked-out Sun and only a small “bite” taken from it. So while millions on Earth stood directly in the umbra and saw the Sun vanish, the astronauts’ orbital track placed them outside that narrow corridor.

3 articles · Updated · Space.com · Aug 14

An 8-frame composite captured the International Space Station silhouetted against the sun on Aug. 12 as the moon carved a partial-eclipse “bite” across the solar disk.
The image was possible because the total solar eclipse aligned the moon, sun and Earth while the ISS also passed through the observer’s line of sight, briefly appearing as a dark shape.
Expedition 75’s 7 astronauts aboard the station also witnessed the event from orbit, including 3 NASA astronauts, 1 ESA astronaut and 3 Roscosmos cosmonauts.
The photograph added an unusual spaceflight element to an eclipse seen by millions on Earth, highlighting how the same celestial event was experienced both from the ground and in orbit.