Interstellar comet passing by Mars seen in rare images

A rare interstellar comet — only the third ever confirmed to enter our solar system — was photographed last week, closely approaching Mars, the European Space Agency said Tuesday. 

The images taken on Friday by two Mars orbiters show a bright, fuzzy white dot of the comet, also known as 3I/ATLAS, appearing to move against a backdrop of distant stars. The comet poses no threat to Earth, NASA has previously said. 

“This was a very challenging observation for the instrument,” Nick Thomas, principal investigator of the CaSSIS camera, said in a statement. “The comet is around 10,000 to 100,000 times fainter than our usual target.” 

Since its discovery in July, Comet 3I/ATLAS has been photographed several times. In early August, NASA and the European Space Agency shared images taken by the Hubble Space Telescope, which captured the comet from about 277 million miles away.

Last month, a new image showed the growing tail of 3I/ATLAS from another star system streaking across our solar system. 

NASA has said the comet will make its closest approach to the sun in late October, passing between the orbits of Mars and Earth. It should remain visible through September before moving too close to the sun to observe, reappearing on the opposite side in early December.

The European Space Agency said Tuesday that scientists will keep analyzing data from both orbiters, combining multiple images from Mars Express in hopes of detecting the faint comet.

Interstellar comets are very rare, astronomers said. Only two other examples have ever been confirmed: 1I/’Oumuamu in 2017 and 2I/Borisov in 2019.