spaceSpace and Physics

Closest Galaxy Collision To Earth Marked With Celestial Fireworks

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Caroline Reid

Guest Author

1806 Closest Galaxy Collision To Earth Marked With Celestial Fireworks
Color image of the collision that formed Kathryn's Wheel. Ivan Bojicic/the scientific team.

Hiding behind the Milky Way was a celestial delight. But it is hiding no more – scientists have spotted a perfect ring of matter drawing a circle around an energetic event in the center. It is the point where two galaxies have collided head on. Such a discovery is an extremely rare sight to behold.

This galactic crash is the closest to the Milky Way ever observed, located at a relatively near 30 million light-years away. The finding has been published in the Monthly Notices of the Royal Astronomical Society.


This type of galaxy merger is known as a "bull's-eye" collision, a tricky event to pull off since the collision must be correctly aligned so that the galaxies' centers meet. If these conditions are met, then the energy from the collision is distributed evenly, throwing off a ring of dust and matter. There are only 20 known systems with this stunning ring formation, one of which is the spectacular Cartwheel Galaxy (right) that's 500 million light-years away.

Within the galaxy collision zone is a hub of activity – pictured in the red image below. Each little bright dot represents a region that is brimming with active star birth. It just goes to show that even destructive processes like this can give rise to the formation of new beautiful objects.

The stellar collision was likened to a firework display found on Earth: the Catherine wheel. In fact, the second author of the paper was so smitten with the galactic beauty of the collision that he named it "Kathryn's Wheel," after both his wife and the firework display. 

“Not only is this system visually stunning, but it’s close enough to be an ideal target for detailed study," said Professor Quentin Parker of the University of Hong Kong, who led the team's research. “The ring is also quite low in mass – a few thousand million Suns, or less than 1% of the Milky Way – so our discovery shows that collision rings can form around much smaller galaxies than we thought.”


Professor Albert Zijlstra of the University of Manchester and second author on the paper commented on their choice of name: “It is not often that you get to name any objects in the sky. But I think Kathryn’s Wheel is particularly fitting, resembling as it does a firework and continuing the tradition of naming objects after loved ones.”

Central Image 1: Cartwheel Galaxy. NASA/JPL-Caltech

Central Image 2: Kathryn's Wheel: The data in this image shows where there are areas of active star formation. Quentin Parker/the scientific team. 


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