Space Photo of the Week: A Cosmic 'Fossil' Containing Some of the Universe's Oldest Stars

What is that: Globular cluster NGC 2005

Where is it: 162,000 light-years away in the Large Magellanic Cloud, a satellite galaxy of the Milky Way, and visible in the constellation Dorado

When it was shared: July 7, 2024

Why it’s so special: This new image from the Hubble Space Telescope shows an object with mysterious origins that is commonly seen in the Milky Way: a globular cluster, a densely packed and gravitationally bound group of tens of thousands or millions of stars. However, NGC 2005 is actually located in the Large Magellanic Cloud (LMC), a dwarf galaxy near the Milky Way, and can be easily seen at night from the Southern Hemisphere.

Globular clusters are believed to be billions of years old. There are about 150 known to exist in the halo of Milky Way. They orbit their center in the opposite direction to most other objects in our galaxy, providing evidence for a theory that they were captured as the Milky Way was merging with other galaxies, according to NASA. This is how astronomers think galaxies evolve and grow. Another clue is that globular clusters host some of the oldest stars in the universe.

Related: The Milky Way will be visible without a telescope this summer. Here are the top nights to observe.

NGC 2005 is the perfect test case because it exists outside the Milky Way but is close enough to be studied carefully. It is about 750 light-years from the heart of the LMC, the largest of the 40 or so dwarf galaxies near the Milky Way. Many of these dwarf galaxies are thought to orbit the Milky Way, although recent Gaia spacecraft data suggest that many of them may just be passing through.

Full-size image of NGC 2005. (Image credit: ESA/Hubble and NASA, F. Niederhofer, L. Girardi)

If galaxies evolve by merging with others, there should be ancient stars in every galaxy whose chemical compositions differ from those around them. This is exactly the case with NGC 2005. It appears to be a relic—possibly the core—of a dwarf galaxy that was consumed long ago.

The LMC can be easily seen from the southern hemisphere on almost any clear night with a good small telescope or a pair of binoculars for stargazing. The LMC is 162,000 light years away. solar systemmaking it one of the closest galaxies to the Milky Way. It contains globular clusters, dense star fields and Tarantula Nebulaa supermassive version of the Milky Way’s Orion Nebula.

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