M4: The Closest Known Globular Cluster . ... Credit Copyright: T2KA , KPNO 0.9-m Telescope , NOAO , AURA , NSF Explanation: M4 is a globular cluster visible in dark skies about one degree west of the bright star Antares in the constellation Scorpius . M4 is perhaps the closest globular cluster at 7000 light years , meaning that we see M4 only as it was 7000 years ago, near the dawn of recorded human history . ... NASA Web Site Statements, Warnings, and Disclaimers . NASA Official: Jay Norris. ...