Many names refer to Messier 55, including M 55 and NGC 6809. NASA’s James Webb Space Telescope’s recent picture shows it as a massive and extremely loose globular cluster. It’s a kind of stable structure that’s filled with millions of stars. All of these stars are bound together due to their gravitational attraction.
These are usually much bigger than open clusters. Their spherical shape can be attributed to their strong gravitational attraction.
Messier 55 was discovered by Abbe Nicholas de la Caille in 1752. Famous astronomer Charles Messier, after whom Messier objects like M 55 are named, had a difficult time locating it.
Despite its massive size and bright appearance, NASA noted that it is difficult to find Messier 55 due to its lack of a dense core.
Also, due to its low position in the sky, it can be hard for observers to spot Messier 55. This is because its surroundings are filled with light pollution and water vapour. Messier was unable to view it properly from his observatory in Paris due to this. He noted that its light doesn’t contain any stars.
Although it may not look like a globular cluster, Messier 55 actually exhibits a spherical shape due to the mutual attraction of its stars.
Messier 55 is around 20,000 light-years from Earth and has a diameter of around 100 light-years. It’s located in the constellation known as Sagittarius. It has around 100,000 stars and 55 variable ones.
Although you can view Messier 55 with binoculars if the skies are clear, it will appear as a hazy patch. You can spot individual stars within M55 using a small telescope or with a larger aperture.