Viewing Globular Clusters

With so many different objects to look at in the night sky, it can be hard to decide what to look at first. All objects are unique and neat to see, be it galaxies, planets, or nebulae. Then there are the globular star clusters which are groups of thousands of stars gravitationally bound to each other, packed into a globular ball around a hundred light years across.

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M80 globular cluster in the constellation Scorpius

These clusters of stars are different from the open clusters, which only contain a few dozen loosely bound stars. The stars in the globular clusters are amongst the oldest stars we’ve discovered, aging between 12 and 13 billion years. Most of the 100+ known globular clusters also orbit our galaxy fairly far away from us, usually between 20 or 30 thousand light years away or more.

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M5 globular cluster in the constellation Serpens

Globular clusters are good targets for beginners because they’re fairly bright and can be easy to find. Several of the globular clusters can be seen in a very dark sky with your naked eyes, as they’re pretty bright for a deep space object. They can also be seen in binoculars and will appear as fuzzy stars somewhat larger than the stars you find nearby. To get the maximum viewing pleasure from globular clusters, using a telescope is a must.

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M22 globular cluster in the constellation Sagittarius

A few nice benefits of viewing globular clusters is that they hold up very well under high magnification, and can even be seen in a finding-scope. You can start out with small magnification, say 30x-40x to initially spot one. Even under lower magnification, you can see individual stars near the edges.

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M13 globular cluster in the constellation Hercules

Once you’ve found your target, increase the magnification to say 100x-150x. You will then be able to make out individual stars within the center of the cluster. Hundreds and hundreds of stars! For those with larger telescopes, like an 8 or 10 inch, go for the gold and up the magnification even more to 200x-250x. At that point, the globular shape starts to break down somewhat as now thousands of individual stars can be made out!

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M2 globular cluster in the constellation Aquarius

All the Messier globular clusters are great for viewing, but a few stand out more than the others due to size, brightness, and ease of finding. A few of my personal favorites include M13, M22, M4 and M5. They’re among the brightest, and you can use a lot of magnification to really coax out the beauty of these globular clusters. There are also some NGC globulars out there as well that are a bit dimmer and a little trickier to find. There’s even the very bright Omega Centauri star cluster that can be seen with the naked eye in southern latitudes.

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M15 globular cluster in the constellation Pegasus

Viewing celestial objects in the night sky can be amazing. Each type of object is a unique view that only the cosmos can provide. Globular star clusters are no exception. With so many stars in all directions in the night sky, it’s really neat to see so many packed in a relatively small space, and its also hard to fathom that most of the stars you see in the globular clusters are triple the age of our planet. So, as you ponder what to aim your telescope at, consider the awesome sight that a globular star cluster may behold!

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