This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: This NASA/ESA Hubble Space Telescope image provides a lesson in galactic history. The sparkling collection of stars is named Messier 30 (M30) after the French astronomer Charles Messier, who cataloged M30 and other diffuse objects that might be mistaken for comets in the early telescopes of Messier's time.
M30 lies about 27,500 light-years away in the constellation Capricornus. M30 is a globular cluster: a roughly spherical grouping of stars containing anywhere from tens of thousands to millions of stars. These clusters generally reside on the outskirts of galaxies, orbiting within a vast, diffuse region called the halo like a swarm of moths around a lightbulb.
Our Milky Way galaxy has at least 150 globular clusters, the nearest of which is about 6,000 light-years away. These clusters are impressively ancient: astronomers estimate their ages are between 11.5 and 13.5 billion years, making certain globular clusters nearly as old as the universe itself. Globular clusters have long played an important role in helping us learn about our galaxy.
More than a century ago, astronomer Harlow Shapley used observations of a particular type of variable star to measure the locations of and distances to dozens of globular clusters within our galaxy. His work showed that the sun is not in the center of our galaxy, and that the galactic center lies toward the constellation Sagittarius. (His distance measurements were incorrect, however, and he concluded that our galaxy is about twice as large as it really is.) Today, astronomers continue to learn about our galaxy by observing globular clusters. Because globular clusters are so ancient, they can give us clues about how our galaxy developed long ago.
Globular clusters that formed within our galaxy can act as time capsules, preserving the original chemistry of our young galaxy. However, it's possible that not all globular clusters that orbit within our galaxy today formed there. Researchers have discovered that M30 and many other globular clusters orbit in the direction opposite from the way our galaxy spins.
This may mean that these clusters did not form within our galaxy at all. Instead, our Milky Way galaxy may have captured them in the distant past. Hubble has observed M30 multiple times.
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