For the first time, a vehicle on the surface of another planet has recorded Earth vanishing behind another celestial body.
NASA's Perseverance rover took the sequence of images on Mars on 2 July 2026. NASA's Jet Propulsion Laboratory (JPL) announced the observation. The Martian moon Phobos passed in front of Earth. Astronomers call such an event an occultation.
The images were taken at about 7 p.m. local time, in the Martian evening. It was the 1,907th Martian day of the mission. The Mastcam-Z camera delivered the frames that were combined into a composite image. The rover stands on the rim of Jezero Crater, which once held a lake.
Earth appears in the frames only as a bright dot. It travels from the upper left towards the lower right, while Phobos crosses its path from the lower left to the upper right. The dot then meets the dark edge of the crescent moon and is gone. Shortly afterwards Earth reappears.
Luck played only a small part in this. "Phobos crosses the Martian sky three times a day, and Earth is visible for months at a stretch, but catching one directly behind the other takes planning and a little luck," said Mark Lemmon of the Space Science Institute in Boulder, Colorado. He planned the observation and assembled the composite image.
The relative sizes explain how a small moon can cover an entire planet. Phobos measures only about 27 kilometres at its widest. It orbits Mars at a distance of some 7,800 kilometres. In the Martian sky it therefore appears about a third as wide as the full Moon seen from Earth, according to JPL. Earth was 314 million kilometres away when the images were taken, and shrank to a single pixel. That is more than twice the distance between Earth and the Sun, notes Spektrum der Wissenschaft.
"The composite image makes for a unique Earth self-portrait, taken from the surface of another planet, with a Phobos photobomb," said Justin Maki, deputy principal investigator for Mastcam-Z at JPL.
Perseverance has recorded comparable events before, with the roles reversed. When Phobos passes in front of the Sun, astronomers speak of a transit, because the smaller-looking body crosses the larger one. Mars rovers have filmed such passes several times, the BBC Sky at Night Magazine reports. An occultation of Earth remains the exception, because the two bodies rarely line up exactly.