Hubble spies a galaxy 2.5 times the diameter of the Milky Way

Enormous galaxy UGC 2885 is 2.5 times the diameter of the Milky Way and home to 10 times as many stars.

It may be the largest galaxy in our local Universe, but UGC 2885 isn’t throwing its weight about. Sitting quietly in a vacant area in Perseus, its beautifully intact disk suggests peaceful millennia have passed without it consuming smaller nearby galaxies or colliding with them.

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Benne Holwerda of the University of Louisville, Kentucky, who observed the giant with the Hubble Space Telescope, has dubbed it Rubin’s Galaxy, in honour of pioneering American astronomer Vera Rubin (1928–2016).

It was her studies of unusual rotation rates in UGC 2885 and other galaxies that pointed to the existence of something invisible at play, an unseen substance with a gravitational influence – dark matter.

Rubin’s Galaxy contains a trillion stars, although the bright star blazing near the centre of this picture isn’t one of them.

That’s a foreground star located 232 million lightyears closer to Earth.

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Observatory Hubble Space Telescope

Release date 5 January 2020

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Image credit NASA/ESA and B. Holwerda (University of Louisville)