Moving at eight kilometers (five miles) per second, the International Space Station (ISS) surrounds our planet every 90 minutes. Over a 24-hour period, ISS crew members experience 16 sunrises and sunsets. Despite the frequency with which the station passes directly between the Earth and the Sun, it is rare to capture an image of the ISS passing over our nearest star.
On June 24, 2020, NASA photographer Joel Kowsky captured such an event from Fredericksburg, Virginia. The image above is a composite, consisting of six frames, and shows the ISS in shape as it moved from right to left across the solar disk as it orbited 400 kilometers (250 miles) above Earth.
The image below shows the position of the ISS in its orbit while Kowsky took his photos at approximately 1:15 pm. Eastern Daylight Time in the United States. The transit lasted about 0.54 seconds and was captured while his camera was shooting at 10 frames per second. Watch a video of the transit below.
Ten sequentially assembled photographs show the International Space Station, with a crew of five on board, in silhouette as the Sun transits about five miles per second, Wednesday June 24, 2020, from Fredericksburg, Virginia. On board are NASA Expedition 63 astronauts Chris Cassidy, Douglas Hurley, Robert Behnken and Roscosmos cosmonauts Anatoly Ivanishin and Ivan Vagner. Photo credit: (NASA / Joel Kowsky) Note: the sequence repeats three times.
Kowsky says many websites help identify when the ISS will pass through the Sun, but time and timing are usually the main problems for taking sharp photos. “With a very limited visibility path along the ground, having clear weather in the identified location is one of the most limiting factors in being able to capture a transit,” said Kowsky, who has had time to spoil a recent attempt. Adequate safety equipment is also required to photograph the sun, as looking directly at it can damage the eyes.
NASA previously published images of the ISS crossing the Sun, even during the total solar eclipse in August 2017. Recent transit images (such as the one below) have also shown a lack of sunspots as the Sun enters a period low solar activity known as solar minimum.
Photograph by NASA / Joel Kowsky. Map of Joshua Stevens Earth Observatory.