Spring is coming, and one of the signs is the rising of the constellation Hercules in the eastern morning sky. Named for the Greek legendary hero, Hercules is a large constellation that contains several deep sky objects worth observing with your telescope. Hercules is easy to find, situated between Draco, Ophiuchus, and Lyra. It’s distinguishing feature is the ‘keystone’ shape at the center. When artistically depicted, Hercules is kneeling on the head of Draco the dragon. Let’s have a look at some deep sky objects you can see in Hercules…
First, we have the M13 globular star cluster. Located to the right (south) of the top left star of the keystone in Hercules, this globular cluster is one of the largest and brightest in the northern hemisphere. It can be seen with the naked eye in dark skies, and looks like a fuzzy star in binoculars. M13 contains several thousand stars in a radius of 84 light years, and is about 22,000 light years away. M13 is a great target for beginners, as it’s easy to find with finder scopes and small telescopes. For those with larger telescopes, M13 can handle quite a bit of magnification, revealing individual stars in the center. Anyone with a telescope should definitely check out M13!
Next, there is the M92 globular star cluster, located to the left (north) of the bottom left star in the keystone, M92 is also bright enough to be seen with the naked eye in dark skies, and also has a fuzzy star appearance in binoculars. M92 is around 27,000 light years away. It’s easy to overlook M92 in lieu of the nearby M13, but M92 is nearly as large and bright. It also holds up very well to higher magnifications, so check out M92 while you’re in the stellar neighborhood.
Another globular star cluster in the area is NGC-6229. This one is located to the left (north) of the upper left star in the keystone of Hercules. Located 100,000 light years away, this globular cluster is smaller and substantially dimmer than the other nearby globular clusters. This one requires a telescope, and won’t be able to take as much magnification. Still, NGC-6229 provides another good example of a globular star cluster when viewed with the other 2 nearby.
Hercules also contains a planetary nebula, NGC-6210. NGC-6210 can be found to the right (south) of the right edge of the keystone. This nebula is fairly bright, and has a bluish-green appearance in a telescope. It’s about 6,500 light years away, and isn’t extemely large in a telescope view. Still, it is one of the more colorful nebulae that can be seen. Most nebulae appear grayish due to the human eye’s inability to distinguish color at low light levels, but NGC-6210 is an exception. Check this nebula out!
The constellation also contains one of the largest structures in the known universe, the Hercules-Corona Borealis Great Wall of galaxies. Discovered in 2013 by measuring gamma-ray bursts, it is thought that the Hercules-Corona Borealis Great Wall is a cluster of galaxies 6-10 billion light years long, and 9.5-10.5 billion light years away. That is an incomprehensibly large structure, containing an untold number of galaxies and stars! While not directly imaged, the evidence seems to point to such a structure existing. Pretty amazing to try and wrap the mind around!
The night sky contains many different objects of many types, and with spring approaching, Hercules makes a great target for both beginners and experienced skywatchers alike. The bright objects are fairly easy to find, and provide a great view. It’s also mind-blowing to think that somewhere in the infinite background, one of the largest structures in the universe may be looming. So, for a wonderous night of skywatching and stargazing, look for Hercules and the objects that are as legendary as the namesake of the constellation!
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