Warm mid-August summer nights offer prime conditions for spotting three magnificent star clusters visible to northern-hemisphere skywatchers in the coming months.
Star clusters are gravitationally bound groups of stars that formed from the same interstellar cloud. These stellar hives range in size from a dozen to hundreds of members and are categorized as open clusters or globular clusters.
Open star clusters typically reside in the dense spiral arms of the Milky Way, where the gravity of passing stars can tug at their outermost members, pulling them apart over the course of millions of years.In contrast, globular clusters are usually found in the galactic halo, above and below the disk. These tightly bound, spherical swarms often contain hundreds of thousands of stellar bodies and play host to some of the oldest stars in our galaxy.
The Milky Way hosts roughly 150 globular clusters and over 1,000 open star clusters, some of which are bright enough to appear as a milky smudge of light to the naked eye from a dark sky location. The deep space targets are easier to spot if you allow half an hour for your eyes to adapt to the dark and scan with averted vision (targeting areas just off-center), where the light-detecting cells — called rods — that excel at ‘scotopic’ low-light vision are focused.
Viewing with the aid of 10×50 binoculars will bring the light cast by a stellar cluster into sharper focus, or even allow you to resolve some of its brighter constituent stars. A telescope with an aperture of 6 inches or more will help reveal the truly magnificent nature of the spectacular star cities that populate the night sky.
A trio of star clusters to spot in August 2025.
The Great Hercules Cluster (M13)
The Great Hercules Cluster, also known as Messier 13, is located some 25,000 light-years from Earth in the constellation Hercules, which can be found nestled between the bright stars Vega and Arcturus, according to EarthSky.org. Once you’ve found it in the hours following sunset, try to identify the diamond-like formation of four stars at the heart of the constellation, known as the ‘Keystone’ asterism. If you need a little help, a smartphone astronomy app can guide you right to your target.
Sweep your binoculars or telescope between the two Keystone stars closest to the nearby constellation Bootes — Zeta Herculis and Eta Herculis — and you’ll spot the ancient light cast out by the 100,000-strong stars of the Hercules globular cluster.
The Hyades open star cluster
Look to the eastern horizon in the hours preceding dawn in August to find the constellation Taurus twinkling to the upper right of Venus and Jupiter. The Hyades is visible as a sideways ‘V’ formation of stars that represents the bull’s face to the right of its two horns, Elnath and Tianguan (Zeta Tauri).
At a distance of just 150 light-years, the Hyades is one of the closest open star clusters to Earth. Aldebaran, the red star that represents the ‘right eye’ of the bull, appears to be part of the cluster, but is actually located a mere 65 light-years from us.
The Pleiades open star cluster (M45)
Celestron Nature DX 12×56
If you’re looking for an affordable pair of binoculars for stargazing, the Celestron Nature DX 12×56 are a good option. They feature excellent build quality, close focussing, good magnification (12x) and a large aperture (56mm). We reviewed the Celestron Nature DX 12×56 and rated them very highly.
The Pleiades is one of the most famous open clusters in the night sky. It plays host to over a thousand white-blue stars, though its appearance is dominated by its seven brightest members when viewed through binoculars, hence its nickname, the ‘Seven Sisters’.
In mid-August, you’ll find the Pleiades roughly 10 degrees above the Hyades in the early morning sky — roughly the width of your clenched fist held at arm’s length.
Stargazers interested in getting a closer view of the night sky should read our roundup of the best telescope and binocular deals available in 2025. Photographers should also read our roundups of the best cameras and lenses for astrophotography.
Editor’s Note: If you would like to share your astrophotography with Space.com’s readers, then please send your photo(s), comments, and your name and location to spacephotos@space.com.
