Messier 4 – Globular Cluster
The fourth object of the Messier catalog (M4) is a Globular Cluster, located in the constellation of Scorpius. It was initially discovered by Philippe Loys de Chéseaux in 1745 and cataloged by Charles Messier in 1764. At a distance of only 5,500 light years away, it is one of the closest globular clusters to our Earth.
M4 was the first and only globular cluster to be resolved into individual stars by Messier himself.
Being located only 1.3 degrees to the red super-giant star Antares, it is very easy to spot.
Messier 4 is home to more than 100,000 stars of which roughly 40,000 are white dwarfs (the cores of ancient dead stars, whose outer layers have drifted away into space).
Facts
Type: Globular cluster
Magnitude: 5.9
Right Ascension : 16h 23m 35.22s
Declination: -26° 31′ 32.7″
Distance: 5,500 light years
Constellation: Scorpius
Best viewed during: Summer
Observation
Messier 4 is one of the easiest globular clusters to locate in the night sky. The reason to that is that it lies only 1.3 degrees of the red super-giant star Antares which is the brightest star in the constellation of Scorpius and is best visible during Summer months.
How to locate it
The first step in locating Messier 4 globular cluster, is to locate the constellation of Scorpius.
This is fairly easy during summer months as in the constellation's center lies Antares, a red super-giant star.
Once you have located Antares, the globular cluster lies only 1.3 degrees to the west (to the right).