M7 (Ptolemy's Cluster) Complete Guide — Open Cluster in Scorpius

Overview

Ptolemy's Cluster (M7) is a Open Cluster located in Scorpius, cataloged as NGC 6475. With an apparent magnitude of 3.3, it lies About 800 light-years from Earth. This Beginner-level object is best observed in the Summer sky.

Open clusters are loose groupings of young stars born from the same molecular cloud. They are commonly found in the disk of the Milky Way and are characterized by their relatively young stellar populations.

Basic Data

Item	Data
Messier Number	M7
Catalog Number	NGC 6475
Object Type	Open Cluster
Constellation	Scorpius
Apparent Magnitude	3.3
Distance	About 800 light-years
Best Season	Summer
Difficulty	Beginner
Required Equipment	Naked eye, Binoculars

Physical Characteristics

This open cluster is located About 800 light-years from Earth with an apparent magnitude of 3.3. It consists of tens to hundreds of stars.

Since the stars in open clusters were born at the same time from the same molecular cloud, they are important objects for studying stellar evolution.

Observation Guide

How to Find

Ptolemy's Cluster (M7) is located in the Scorpius region. It transits around 20:00–22:00 during Summer, making it well-positioned for observation. It is bright enough to see with the naked eye, but use the main stars of Scorpius as guide stars and confirm the exact position with a star chart or app.

Observation Tips

Open clusters are best viewed with binoculars or low-magnification telescopes. Since they are spread-out objects, avoid using too much magnification. Notice the different colors of the stars.

Recommended Equipment

As a bright object, it can sometimes be spotted with binoculars even from urban areas.

Astrophotography Tips

For photographing Ptolemy's Cluster (M7), prime-focus astrophotography with a camera attached to a telescope is recommended. Use a tracking mount and appropriate exposure times.

Summary

M7 is a Open Cluster observable in Scorpius, rated Beginner level. Relatively bright, it is recommended even for beginning observers. Try observing it in the Summer night sky!