Messier 4 is a globular cluster located in the constellation Scorpius. It is approximately 7,200 light-years away from Earth and contains hundreds of thousands of stars. This cluster is one of the closest to our planet and is notable for its relatively loose structure compared to other globular clusters. Discovered by Charles Messier in 1764, Messier 4 is best observed with telescopes. It has a diameter of about 75 light-years and is thought to be around 13 billion years old. The cluster is also home to several variable stars, making it an interesting target for astronomers.