American astronomer Halton Christian Arp passed away in Munich, Germany, on December 28. He was 86. Arp was a world-renowned expert on interacting and merging galaxies. His 1966 book Atlas of Peculiar ...

Halton Arp was an American astronomer. He was known for his 1966 Atlas of Peculiar Galaxies, which (it was later theorized) catalogues many examples of interacting and merging galaxies, though Arp ...

Colliding galaxies may be common, but cosmic cacophony on this scale is still unusual. What we have here are two galaxies merging together in your standard collision…and then a third galaxy sidling in ...