Deep-Sky Dreams: NGC 7789

Discovered by Caroline Herschel in 1783, NGC7789 is not only one of the richest open star clusters you're likely to observe, but also one of the oldest.
By | Published: May 30, 2025 | Last updated on July 10, 2025

Image of a densely populated star field showing the open star cluster NGC 7789, also known as Caroline’s Rose Cluster, situated in the constellation Cassiopeia. The image is filled with countless small stars, and the central cluster appears as a slightly more concentrated region of stars forming a subtle rose-like pattern. The background is a deep black space with thousands of bright and faint stars of varying colors, including white, blue, and yellow hues.
One of the richest concentrations of stars in the northern sky exists in the big open cluster NGC 7789 in Cassiopeia, a great sight for binoculars or a small scope. Credit: Alan Dyer
Gemini Sparkle

Key Takeaways:

  • NGC 7789 is an open star cluster situated in Cassiopeia, discovered by Caroline Herschel in 1783, and is also known by appellations such as "Caroline’s Haystack."
  • This celestial object is a relatively old cluster, estimated to be 1.7 billion years old, and is located at a distance of 7,600 light-years from Earth.
  • It comprises approximately 1,000 stellar members, collectively accounting for a total mass of about 6,600 solar masses.
  • Visually, the cluster exhibits a combined magnitude of 6.7 and spans an angular diameter of 16 arcminutes, characterized by a rich population of relatively faint, widely dispersed stars.
Key takeaways sponsored by The Space Store

When you’re gazing at objects in the northern sky, do not forget to look at one of the richest open star clusters you’ll ever see. NGC 7789 in Cassiopeia is particularly notable for its huge mass of relatively faint stars, all set in a rich Milky Way star field, which makes for a great scene in binoculars or a small telescope. 

NGC 7789 was discovered by Caroline Herschel in 1783, and it’s sometimes called “Caroline’s Haystack,” “Caroline’s Rose,” or the “White Rose Cluster.” 

This object is a relatively old open cluster at 1.7 billion years. It lies a healthy 7,600 light-years away. 

It’s hard to find a more spread-out cluster as richly populated as this one in many places in the sky. NGC 7789 has a combined magnitude of 6.7 and it spreads over 16’, half the diameter of the Full Moon. 

This great cluster contains about 6,600 solar masses of material, with a stellar membership of approximately 1,000 Suns.

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