Messier 5 is one of the oldest and most massive globular clusters in our galaxy, containing over 100,000 stars tightly packed into a brilliant sphere. Its dense core and extended halo make it a spectacular target for astrophotographers, offering both a bright central region and delicate outer structures to capture. The cluster is especially known for its population of variable stars and its golden-hued appearance in long-exposure images. M5’s combination of brightness, size, and intricate detail make it a rewarding subject for both beginners and experienced astrophotographers.
Names and Catalog numbers
- Messier 5 (M5)
- NGC 5904
- Melotte 133
Position and the cosmic neighborhood
Messier 5 is located in the northern part of the constellation Serpens (specifically Serpens Caput), about 11 degrees northwest of the bright star Alpha Serpentis (Unukalhai). It sits in a relatively sparse region of the sky, making it easy to identify and image without interference from nearby bright stars or deep-sky objects. The cluster is positioned near the border with the constellation Virgo, and under dark skies, it can be found as a faint, fuzzy star with binoculars. The surrounding area is rich in faint background stars, which can add depth and context to wide-field astrophotography images.
Nice to Know
- Messier 5 is estimated to be around 13 billion years old, making it one of the oldest known globular clusters.
- It contains more than 100 variable stars, one of the highest numbers in any globular cluster.
- M5’s stars are often described as having a golden hue in photographs due to their age and composition.
- The cluster’s dense core can be challenging to resolve, providing an excellent test for telescope optics and astrophotography skills.
Brightnes, distance and size
Messier 5 has an apparent magnitude of about 5.7, making it visible to the naked eye under excellent dark-sky conditions and easily seen with binoculars or small telescopes. The cluster is located approximately 24,500 light-years from Earth and spans about 165 light-years in diameter. In the sky, M5 covers an area of roughly 17.4 arcminutes, slightly more than half the apparent diameter of the full moon. Its combination of brightness and size makes it a standout target for both visual observation and detailed astrophotography.