The lunar eclipse of Sept. 7/8, 2025, was not favorable to observers in the Americas or Europe, but was well-placed for viewers in Asia. Tianyao Yang took the opportunity to capture the silhouette of the Chinese space station Tiangong (or “heavenly palace”) as it crossed the Moon during the eclipse.
The International Space Station has previously been captured in transit across a Moon in Earth’s shadow, notably by astrophotographer Thierry Legault during the Sept. 28, 2015 eclipse. Yang decided to do the same for Tiangong — and to distinguish his image by blending the transit sequence with a high dynamic range (HDR) capture of the Moon, retaining detail in the umbra, the deepest part of Earth’s shadow.
To plan the shot, Yang started with the orbital parameters of Tiangong, published by the China Manned Space Agency in Orbital Ephemeris Message (OEM) format. Yang used the mobile app Planit Pro to convert the OEM data into the more common two-line element (TLE) format and visualize the path of the space station across the eclipsed Moon. “With this information,” he says, “I only needed to select an observing site with favorable seeing conditions” — which wound up being outside the city of Chifeng, China.
There was another consideration: “I deliberately chose a spot slightly offset from the central transit line,” says Yang. “This way, the station’s silhouette would pass across the brighter portion of the eclipsed Moon, avoiding the darker umbral region where the track could have been less distinct or incomplete.”
The resulting sequence comprises 22 frames across just 0.72 second — scarcely perceptible in video, but leaving a strong impression in an image.
