Butterfly Cluster (M6): A Wing-Shaped Cluster in Scorpius

What It Is

The Butterfly Cluster, catalogued as Messier 6, is an open star cluster — a loose group of a few hundred stars born from the same cloud of gas and still loosely bound by gravity. Its brightest members trace a shape that early observers read as a butterfly's outstretched wings, which is how the nickname stuck. Unlike a globular cluster, an open cluster like M6 is a relatively young, sparse gathering, and its stars will drift apart over the coming hundreds of millions of years.

Constellation & Distance

M6 sits in Scorpius, low in the southern sky for observers in the Northern Hemisphere and well-placed for southern latitudes. It lies roughly 1,600 light-years from Earth, making it one of the closer open clusters commonly targeted by amateur observers.

Why It's Worth Seeing This Month

Scorpius rides highest in the evening sky during the Northern Hemisphere summer, and July puts M6 in a convenient position for an after-dark session without waiting until the small hours. Under genuinely dark skies, the cluster is bright enough to pick out with the naked eye as a hazy patch — a rare case where no optical aid at all still yields a result.

Equipment: Visual vs. Astrophotography

Visual: Binoculars or a small, wide-field telescope at low power are the ideal match. The cluster spans roughly half a degree — wider than the field of view many telescopes deliver at moderate-to-high magnification — so more aperture isn't necessarily better here; a wide, low-power view usually shows more of the cluster's actual shape.

Astrophotography: A short focal length refractor captures the full cluster in one frame along with its surrounding star field. Because the cluster's stars are relatively bright, exposure times can stay short compared to faint nebulae, making it a forgiving target for imagers still refining their workflow.