While millions of Americans gather across the country to catch a glimpse of Monday’s total solar eclipse, the astronauts aboard the International Space Station will view the event from a much different vantage point.
The ISS crew members are predicted to view both a partial eclipse and the moon’s shadow cast on the North American continent as they make three tracks around the planet 400 km above Earth’s surface, according to NASA.
“Observing a total solar eclipse from manned spacecraft is difficult though not impossible,” NASA reported.
NASA said the different rates of speed and intersecting paths are the main challenge to viewing an eclipse from space.
At minimum, ISS spends less than 15 seconds traversing the 100-km-wide lunar shadow even when the paths align in space and time, according to NASA. However, Earth’s horizon extends nearly 2,300 km from the ISS, allowing astronauts to see the lunar shadow if they are close enough during the event.
The International Space Station (ISS) was in position to view the umbral (ground) shadow cast by the moon as it moved between Earth and the sun during a solar eclipse on March 29, 2006. This astronaut image captures the umbral shadow across southern Turkey, northern Cyprus and the Mediterranean Sea. (Photo/NASA)
The total eclipse will begin on the Oregon coast at 17:15 UT (10:15 a.m. PDT) and will end along the South Carolina coast at 18:49 UT (2:49 p.m. EDT).
As the space station makes its first pass during the eclipse, the crew members will be able to view a partial solar eclipse with approximately 37 percent of the sun covered up, NASA reports.
However, at this point in time, the ISS will not be able to see the umbra, or the darkest part of the moon’s shadow on the Earth’s surface. The space station will pass over the western United States and southeastern Canada in the first pass. The total portion of the eclipse will not have started yet for the Earth.
As the station makes its second pass through the moon’s shadow, the partial eclipse will be visible to the astronauts with 44 percent of the sun covered.
“ISS will witness the moon’s umbra moving from southwestern Kentucky to northern Tennessee during a portion of this pass,” NASA reports.
“The moon’s umbra is visible on the Earth from ISS’s viewpoint while ISS traverses from southern Canada just north of the Montana-Canada border to the Gulf of Saint Lawrence.”
At its closest approach, the space station will be making its way south of the Hudson Bay, far removed from the moon’s umbra, which will be passing over southwestern Kentucky nearly 1,700 km away.
However, despite the distance, crew members aboard the ISS should still be able to view the shadow near the horizon.
The third pass for the ISS will bring another view of a partial solar eclipse with 85 percent coverage just minutes before orbital sunset. At this point, the darkest part of the lunar shadow will no longer be visible to crew as the umbra will have lifted from the Earth’s surface as it makes its transit.
“Because of atmospheric friction and other ISS activities, the orbits undergo small changes from week to week,” NASA reports.