The Double Cluster is one of the best sights in our night skies for those with telescopes, even small ones. Imagine exploring a sparkling cluster of countless stars next to another dazzling cluster of countless stars and you get the idea. So bright and so beautiful... it is no wonder that we keep going back to it night after night!
Although the Double Cluster is in Perseus, we use the constellation Cassiopeia to find it. It's simple. Find Segin and Ruchban, the two bright stars on the left end of Cassiopeia's 'W'. Now look down for a hazy glow assuming you are viewing from dark skies. The Double Cluster forms the third point of a triangle with the two stars above. Now train your telescope on the glow and.... oh my God!
The two open clusters are technically known as NGC 869 and NGC 884. Each may consist of thousands of stars. They are at a distance of 7500 light years which, compared to the size of our Milky Way Galaxy, puts them fairly close to us and helps explain why they dazzle to our eyes.
Viewing Double Cluster
Level
Moderate
Rating
Best Viewing
September through February
Find
To find the Double Cluster, first find Cassiopeia and its stars Segin and Ruchbah. These are 5° apart, or 3-fingers held at arm's length. Study the pic above to see that the Double Cluster forms the third point of a triangle below at 7°, or 4-fingers at arm's length.
To the naked-eye from a dark sky site, the Double Cluster will appear to be glowing dimly.
Use binoculars to confirm the Double Cluster.
With a telescope, at low power, find the Double Cluster. Try to frame both clusters in the same field of view. Then increase power to see more details. Enjoy the view!
