A globular cluster of several hundred thousand stars

Hercules Globular Cluster

August 15, 2023

The Hercules Globular Cluster (also known as Messier 13 or NGC 6205) is one of the most famous and visually stunning globular clusters in the night sky. Located in the constellation Hercules, about 22,000 light-years from Earth, it is one of the brightest and largest globular clusters visible from the northern hemisphere. With a diameter of around 145 light-years, the cluster contains several hundred thousand stars, mostly older, red giant stars, tightly packed together. Its sheer density of stars makes it a captivating target for astronomers and stargazers alike.

M13 is easily recognizable through binoculars or small telescopes, where it appears as a dense, fuzzy ball of light. Through larger telescopes, the individual stars become more resolved, revealing the true splendor of this densely packed stellar system. The Hercules Globular Cluster orbits the galactic core in a highly elliptical orbit, at a speed of approximately 220 kilometers per second. Its stars are primarily composed of older, metal-poor stars, which suggests the cluster is one of the earliest formed objects in our galaxy.

Hercules Globular Cluster (M 13)

Astronomically, M13 is a great example of a globular cluster—a spherical collection of stars that orbit the galactic center and are typically made up of ancient stars. These clusters offer valuable insights into the early stages of galaxy formation and the evolution of stars. The Hercules Globular Cluster is also famous for being home to several variable stars, as well as a fascinating X-ray source that has intrigued astronomers. M13 is often referred to as the “Great Hercules Cluster” due to its size and prominence in the sky, and it remains a favorite of amateur astronomers for its beauty and complexity.

Nikon D750 at 300 mm on Star Adventurer GTi

Aperture

Exposure

ISO

Stacked Images

Wisconsin, United States

Constellation

Hercules

Distance

22,2000 light-years

Number of Stars

300,000-500,000

Apparent Magnitude

5.8

Where to Find It

Find the Hercules Globular Cluster

To find the Hercules Globular Cluster (M13) in the night sky, first locate the constellation Hercules, which is visible in the northern hemisphere during the late spring and summer months. Start by finding the bright star Rasalgethi (Alpha Hercules), which marks the head of the Hercules constellation. From there, look for the keystone-shaped asterism, which forms the body of Hercules. The Hercules Globular Cluster (M13) lies just slightly to the left of the keystone, near the center of the constellation. Under dark skies, M13 is visible to the naked eye as a faint, blurry patch, but using binoculars or a small telescope will reveal its striking, dense star cluster structure. It’s best observed when the constellation is high in the sky, around midnight during the summer months.