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Adopted Cluster

November 30, 2019

The Milky Way Galaxy is a big mishmash of stars with different origins. Some, such as our own Sun, were born in the Milky Way itself. But many others were born in other galaxies. These galaxies merged with the Milky Way, and our galaxy made their stars its own.

An immigrant star cluster is low in the south-southwest at nightfall. It’s about 27,000 light-years away, near the triangular outline of Capricornus, the sea-goat, which is close to the upper left of the Moon this evening. Through binoculars, the cluster looks like a small, hazy smudge of light.

Messier 30 is a globular cluster. It contains more than 150,000 stars, all packed into a ball that’s only about a hundred light-years in diameter.

Many of its stars, though, are jammed into the cluster’s core — a region that’s just one light-year across. By comparison, the closest star system to the Sun is more than four light-years away. So if there are any planets in the core of M30, their night skies would be ablaze with thousands of brilliant stars — so many that the night would never really get dark.

M30 orbits the center of the Milky Way in the opposite direction from most stars and star clusters. That suggests it was born in another galaxy. That galaxy merged with the Milky Way. Over time, the other galaxy’s stars and clusters spread through Milky Way — adopted members of our vast galactic home.

Script by Damond Benningfield

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