Dwarf Galaxies Found Orbiting The Milky Way, Like Galactic Moons

The illustration you see above maps out the previously discovered dwarf satellite galaxies (in blue) and eight of the newly discovered candidates (in red) as they sit outside the Milky Way. The image was put together by Yao-Yuan Mao, Ralf Kaehler, Risa Wechsler (KIPAC/SLAC)

Astronomers were stunned by the discovery of nine potential dwarf galaxies orbiting our galaxy. It marks the largest number ever discovered at once. The findings were published in two studies available on arXiv.

Dozens of dwarf galaxies were spotted in 2005 and 2006 above the northern hemisphere. The nine new galaxies were found in a small patch of sky above the southern hemisphere near the Large and Small Magellanic Clouds. These galaxies are about a million times smaller and a billion times dimmer than the Milky Way itself. This makes them a challenge to find.

“These results are very puzzling,” Cambridge’s Wyn Evans says in a news release. “Perhaps they were once satellites that orbited the Magellanic Clouds and have been thrown out by the interaction of the Small and Large Magellanic Cloud. Perhaps they were once part of a gigantic group of galaxies that—along with the Magellanic Clouds—are falling into our Milky Way galaxy.”

“Dwarf satellites are the final frontier for testing our theories of dark matter,” Vasily Belokurov of Cambridge explains. “We need to find them to determine whether our cosmological picture makes sense.”

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