Messier 35 is a well-known open cluster in the Gemini constellation – a great visual observation target for binoculars and for telescopes of any size. Next to it, there is an NGC 2158 star cluster. If you take a look at this cluster, you may immediately think that it is a globular cluster, because its symmetry seems to be obvious. It was once thought to be a globular cluster, and now it is known to be an intermediate-age open cluster that is a member of the Milky Way’s old thin disk population. NGC2158 is located about 16,500 light-years away from us, and it is believed to be about 2 billion years old, which is pretty much for an open cluster. It was discovered by William Herschel (no surprise here) on November 16th, 1784.
Messier 35 (also known as the Shoe-Buckle Cluster) is located about 2,770 light-years away from us, and its age is estimated to be 150 million years, so it is many times younger than NGC 2158. Due to its relative proximity, its apparent brightness is much higher than that of NGC2158, and it was also discovered earlier, in 1745, by Swiss astronomer Philippe Loys de Cheseaux. It contains 120 stars brighter than 13 mag – so available for visual observations with a telescope of 6-8 inches in diameter. The total number of stars in Messier 35 is probably over 500.
Even more to the right, there is a small and not well-defined yet another open cluster – IC2157. Not much data is present on it, however, it was also catalogued as Collinder 80 and Trumpler 4 in other star open clusters catalogs.
I have already imaged these star clusters several times, but this spring I decided to capture more data. Due to this fact, the whole frame is now filled with Milky Way stars, and the star clusters gained a new context. Though they are now maybe a bit lost among the Milky Way stars 🙂
Image technical data: Date: March 2025 Location: Nieborowice, Poland Telescope: TS Photoline 130/910 Corrector: TS FF/FR 0.8x Camera: QHY268M Mount: EQ6 Guiding: ASI290MM + Evoguide ED50 Exposures: LRGB 250:120:60:80 minutes Conditions: Bortle 6, transparency and seeing medium-good, high clouds
Pikne 🙂