Ptolemy’s Cluster

Designation: M7 / NGC 6475
Hemisphere: Southern
Constellation: Scorpius
Distance: 980 light years
Object type: Open cluster


NGC 6475 is an open cluster of stars located in the southern constellation Scorpius, some 980 light years from the Sun. The cluster has an estimated age of approximately 200-220 million years and contains around 80 stars.

First observations of this cluster date back to the 2nd-century, when the Greek-Roman astronomer Ptolemy (hence the name) described it as a nebula in 130 AD. The Italian astronomer Giovanni Batista Hodierna then observed it in 1654, counting about 30 stars, before French astronomer Charles Messier included the cluster in his catalogue in 1764, as item number 7.

Acquisition details

Total integration time: 7 hours
Acquisition software: CHI-1 (Telescope Live)
Processing software: PixInsight
Location: Chile

Full size image

Where the universe begins…