A picture of the space station passing the sun in just half a second

Juan Carlos Casado photographed the Tiangong Space Station (TSS) passing in front of the sun, capturing the outlines of the spacecraft’s modules and solar panels.

Casado spent two weeks preparing to take over the Chinese TSS, which is still under construction, from his backyard in Figueres, Spain.

married talking betapixel He had to know until a second when TSS would be shaded by the closest star to Earth.

“Traffic forecasts for space stations like Tiangong or the International Space Station can be obtained from the Transitfinder.com website,” he says.

“I had known that this pass could be observed from my house for about two weeks before that. As the passing day approached, the time and geographical position had to be recalculated, because the orbital parameters of the space stations vary.”


Casado used the Time app, which simultaneously connects to several atomic clock servers, and usually guarantees accuracy to within three milliseconds or better.

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“Having a telescope with good optics and its focal length combined with the resolution of the camera would allow me to capture details of the spacecraft, which had apparent dimensions of only about seven inches,” he explains.

Casado has a Russian, Newton-Maksutv telescope with a 152mm aperture and 900mm focal length attached to a Sony A7R III camera.

“The theoretical resolution is about an inch, which in theory (in ideal weather conditions) will allow me to capture the details of the spacecraft,” Casado explains.

The Spaniard then had to consider the exposure time because crossing through the solar disk would be less than a second – a fast shutter speed was required.

“To photograph with a fast shutter speed, the solar image must be bright enough, i.e. the solar filter must not be too dense and a relatively fast telescope is needed,” he says.

“Using an aperture filter, I was able to shoot at 1/3200 sec., which was within the theoretical resolution I could get (with the camera’s ISO as low as possible).”

Casado had to start shooting a long blast in RAW before the TSS’s scheduled transit time.

“My camera, along with the high-speed recording card, allows me to take 10 frames per second burst images for several seconds,” he explains.

“In total, there were about 130 images, six of which show Tiangong, although the image on the left edge shows only part of the solar panel.”

With all the control details in place, one thing Casado couldn’t explain was the weather. The forecast that day was for cloudy weather but the astrophotographer got a lunch spot.

“A few minutes before Tiangong passed, the sky miraculously cleared and I was able to make the observation.”

RAW file
The image was extracted directly from the RAW file | Juan Carlos Casado

For the final image, Casado combined the images to get a higher resolution as well as to show the TSS path.

“In image processing, I made traditional adjustments (color balance and contrast) and used waves to improve detail.”

Space station under construction

TSS is nearing completion and will become the only independent space station, unlike International Space Station (ISS) is a multilateral effort.

On July 24, China launched a 23-ton research laboratory unit to Tiangong, which means “heavenly place,” and the country expects to conduct research in biology and life sciences.

Tiangong will have its own strength, propulsion, life support systems, and living quarters. It is also designed to provide refueling power for an upcoming Chinese space telescope, called the Xuntian.


Casado travels extensively to capture natural phenomena and recently published a book called travel astrophotographywhich is available over here.

More of his works can be found at flickr And the Instagram.

Image credits: All photos by Juan Carlos Casado.