Photographer Captures ISS Crossing the Sun During Astronaut Spacewalk

Spacewalk in progress

An astrophotographer captured the International Space Station (ISS) crossing the Sun as two astronauts were conducting a spacewalk to install solar panels.

Thierry Legault drove six hours from his home in France to a vantage spot in the Netherlands so he could capture the ISS crossing the Sun an hour after astronauts Steve Bowen and Woody “Woody” Hoburg had begun their spacewalk to install a new solar array outside the station.

ISS solar transit

The solar transit lasted just 0.75 of a second as the ISS hurtled across the face of our nearest star at a speed of 16,777 miles per hour (2,700 kilometers per hour).

Each frame that Legault captured was shot at 1/32000 of a second with an OM-1 attached to a CFF 200mm refractor with a Baader Herschel wedge and an Emmanuel Rietsch’s GPS trigger.

ISS solar transit

“Using real-time images of the Sun, I estimated the position of the main sunspot groups towards vertical and horizontal directions (which depends on time and location),” Legault tells PetaPixel.

“I compared it to the trajectory planned by, and I tried to place myself on the corresponding transit line (which was not the center of the transit visibility path).”

“I never make ISS transits from stackings or assemblies,” he adds on Twitter.


Eagle-eyed viewers will have spotted the sunspots present on the Sun’s surface in Legault’s photos which he says are larger than the Earth.

“The ISS passed in front of three sunspots groups in a split second,” he writes on Facebook. “The big sunspot could swallow the Earth, but it is 300,000 times farther than the ISS.”

ISS solar transit

He adds that despite the ISS and the Sun looking like they are near one another, the Sun is a staggering 94 million miles away (150 million kilometers) from Earth while the ISS is a mere 342 miles (550 kilometers) from home.

ISS solar transit

Spacewalking Astronauts

NASA astronauts Bowen and Hoburg completed all of their objectives while installing an International Space Station Roll-Out Solar Array (IROSA) that will augment power generation for the 1A power channel on the station’s starboard truss structure.

The new arrays are 60 feet long by 20 feet wide and each new IROSA will produce more than 20 kilowatts of electricity.

More of Legault’s work can be found on his Twitter, Facebook, and website.

Image credits: All photos by Thierry Legault.