Star Clusters of the Scorpion

Constellation of Scorpius

Hanging low in the southern sky from early spring until autumn is the constellation Scorpius, the scorpion. Scorpius is reasonably large, and has several features for you to aim your telescope at. As it lies along the path of the ecliptic, you may even get lucky and spot a planet or two, such as Mars and Saturn, which both currently are passing through Scorpius.

The mythology of Scorpius is linked with Orion, the hunter and one of the prominent constellations of winter. According to myth, Orion boasted that he could kill any animal on Earth. The Greek goddess Artemis, twin sister of Apollo, was a protector of all creatures, and so she sent Scorpius to do battle with Orion. After a legendary battle, Scorpius gained the upper hand and killed Orion, and gained the attention of Zeus. Zeus placed Scorpius in the heavens, and also placed Orion in the heavens as well after Artemis requested. Orion serves as a reminder to humans to refrain from excessive pride. So, during the winter, Orion hunts, and then flees Scorpius in the spring.

One of the notable features of Scorpius is the bright reddish star Antares, also known as the “heart of the scorpion”. Antares is a red supergiant that lies approximately 550 light years from Earth. It is so large that if Antares was located where the Sun is in our solar system, Antares’ outer surface would extend between the orbit of Mars and Jupiter. Antares also has a companion star that appears green in color, though it is fairly difficult to spot.

As Scorpius lies in the direction toward the center of the Milky Way, the only galaxy that can be seen is our own. The center of the Milky Way lies in between Scorpius and Sagittarius. There are, however, several star clusters that can be seen in Scorpius worth pointing your telescope at. Let’s take a look at some of these…

M4 globular cluster

Lying just to the west of the bright star Antares is the M4 globular cluster. Appearing fairly large in a telescope, M4 is the first globular cluster in which individual stars were distinguished. It is also one of the closest, being only 7,200 light years away. M4 is a fine example of a globular cluster, and can withstand a lot of magnification. See if you can distinguish the individual stars!

M80 globular cluster

Just above and slightly left of M4 is another globular star cluster, M80. M80 is approximately 33,000 light years away. While not visually as large as M4 in a telescope, M80 is more dense, containing several hundred thousand stars within a 95 light year radius. M80 is slightly more faint than M4 as well.

M6 Butterfly Cluster

Above and to the left of the tip of the tail of Scorpius is the Butterfly Cluster, M6. Due to its proximity to the southern horizon, it may be difficult to view from the higher northern latitudes. M6 gets its name because it vaguely resembles the shape of a butterfly. It lies around 1,600 light years away. It can be viewed in binoculars, and may even be seen with the naked eye in dark skies with a clear view of the southern horizon.

M7 Ptolemy Cluster

Underneath M6 in the sky, we have the Ptolemy Cluster, named after the Greek astronomer who first spotted it, mistaking it for a nebula. M7 is visible to the naked eye as well in dark skies with a clear view south. M7 lies even more south than M6, making it the most southern Messier object. Located around 1,000 light years away, you will see 70-80 stars when viewing M7. You can also see it in binoculars. As with M6, you may not be able to spot it if you live farther north.

Open star cluster NGC-6231

And lastly, we have the open cluster NGC-6231, also sometimes called the “Northern Jewel Box”. NGC-6231 is located under Antares, on the right side of where the tail “hooks” under Scorpius. As this cluster lies near the southern horizon, this may be another tough cluster to spot the farther north you live. This cluster is moving towards our solar system at 10 miles per second, and is just under 6,000 light years away. This star cluster, like its nickname suggests, is full of very beautiful stars, and is a real treat to glimpse!

Scorpius is a beautiful constellation to see, and contains several gorgeous star clusters as well as the center of the Milky Way in the deep background. From the bright red supergiant Antares to the globular and open star clusters it contains, Scorpius is a great spot to aim your telescope. See how many clusters you can find, and don’t be afraid to scan the region slowly with your telescope and view the vast number of distant stars forming the center of our galaxy!

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