A shining moment

The Wheaton Observatory recently captured a half-second of video that many astrophotographers have waited in vain for years to record.

The high-speed video images made by Assistant Professor of Astronomy Dipankar Maitra show the International Space Station (ISS) streaking across the face of the Sun at more than 17,000 miles per hour just before 10 a.m. on Sunday, April 23.

“We did it!” Maitra announced to his colleagues after reviewing the videotape. “I thought I had failed; it happened so fast! When I got back home, I was going through the video frame by frame and found that we actually managed to capture the International Space Station fly right in front of the sun (as seen from our observatory).”

To the lay person, a slowed-down, 13-second replay of the video might not seem to be a cause for celebration. But the video will have real educational benefits, and the hurdles to capturing it were significant.

Maitra explained the challenge this way: the space station transits the sun only once every few months, but it is not a predictable event. The orbit of the ISS varies significantly due to air drag, making it impossible to know more than a couple of weeks in advance of when it will pass in front of the Sun. In addition, it is not always visible from Norton (or anyplace else) due to its low-Earth orbit. And finally, the skies need to be clear at that moment.

So why bother? Maitra said the exercise offers a vivid demonstration of some of the many capabilities of Wheaton Observatory equipment. (This video was shot using a CPC-1100 11-inch telescope outfitted with a solar filter and a Canon digital camera controlled by laptop.)

“Capturing this image gives us a way to appreciate the amazing technology that has put human beings in a spacecraft orbiting the Earth, as well as the technology that allows for such a detailed view of this distant outpost silhouetted against our sun, complete with a sunspot or two,” he said.

The video also has teaching benefits. For example, it may inspire students to devise other projects. In addition, Maitra said that he and professors Anthony Houser and Tim Barker are talking about how to use the video in class.

“For example, knowing the actual size of the space station and measuring how big it appears on our images, students can find out how far the ISS is from Earth and how fast it is moving,” Maitra said. “Another excellent exercise would be to find out how big those sunspots shown in the video are.”

Professor Maitra knows, but is keeping the answer to himself for now.

The International Space Station transiting the sun as recorded from the Wheaton College Observatory on Sunday, April 23.