asteroid Crab Nebula
© ESA/Hubble & NASA, M. Thévenot (@AstroMelina)
The asteroid was snapped streaking across the nebula.
After NASA and the ESA threw open the Hubble Space Telescope archives to amateur astronomers, one of them managed to find a stunning 'photobomb' of an asteroid crossing in front of the mesmerizing Crab Nebula.

The US and European space agencies started the Hubble Asteroid Hunter citizen science project in June, but were not prepared for the overwhelming enthusiasm shown by over 1,900 volunteers who managed to complete 300,000 classifications of nearly 11,000 images in only 1.5 months, blowing past even the most optimistic expectations for the project.

One astronomy enthusiast in particular, Melina Thévenot from Germany, discovered a captivating image while trawling through the archives. Thévenot processed different versions of a 2005 image of the Crab Nebula, combining views taken in blue, green and red filters, and found the trail of asteroid 2001 SE101 is visible near the nebula's center.

The Crab Nebula, also known as Messier 1 or M1, is the expanding remnant of a supernova explosion first observed by astronomers in 1054. The rapidly spinning neutron star left behind after the explosion is visible at the centre of the image as well (it is the leftmost star in the binary pair).

Now that the project is completed, professional astronomers can begin plotting the orbits and future trajectories of the asteroids identified with greater accuracy than ever before. This research, in turn, will feed into our planetary defence models and may one day help prevent possible impacts.