Seeking Globular Cluster M4

Scorpius

One of the most interesting globular clusters in the entire sky is M4, in Scorpius.

One of my favourite Scorpius targets is globular cluster M4. Here’s how to find it.

Scorpius

This image simulates the view of M4 in 10×50 binoculars.

M4 is easy to locate since it lies in the same binocular field as the first-magnitude orange star, Antares. The trouble with most globular clusters is that they look like slightly out-of-focus stars in typical binoculars. Not so with M4. Even in 7× binos, the cluster is easy to identify as a small, round, diffuse glow. A telescope will resolve M4 into a ragged clumping of starlight, and if you look closely, you might be able to make out a chain of stars running across the cluster’s face. One reason M4 looks different from typical globulars, like M13 in Hercules, is that it’s so close. M4 is estimated to lie only 7,200 light-years away, which makes it the nearest globular in the Messier catalogue, and second closest of all.

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