By Michelle Starr
Just as moons orbit planets, planets orbit stars, and stars orbit galactic cores, galaxies can be orbited by other, much smaller galaxies. The Milky Way has several of these hangers-on, most notably the Large and Small Magellanic clouds, the only two of our galaxy’s satellites visible to the naked eye.
Now, thanks to Gaia data – the most comprehensive map of our sky ever compiled – astronomers have just found another one. And it’s absolutely huge – as big as the Large Magellanic Cloud, or about one-third of the size of the Milky Way.
In the picture above, it’s the dim glow in the upper left of the image, located adjacent to the Milky Way (bottom left), with the Large Magellanic Cloud pictured on the bottom right.
Since it’s located in the southern constellation Antlia (The Pump), it’s been given the name Antlia 2.
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