Messier 7 facts for kids
Messier 7, also known as NGC 6475 or the Ptolemy cluster, is a group of stars called an open star cluster. It is found in the constellation of Scorpius, which looks like a scorpion in the night sky. This cluster is about 980 light-years away from Earth. A light-year is the distance light travels in one year, which is a very long way!
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What is an Open Star Cluster?
An open star cluster is a group of up to a few thousand stars that were all born from the same giant cloud of gas and dust. These stars are loosely held together by gravity. They are usually young stars and are found in the flat, spiral arms of galaxies, like our own Milky Way.
The Ptolemy Cluster
Messier 7 is often called the Ptolemy cluster. This is because the ancient Greek astronomer Ptolemy first wrote about it in the 2nd century AD. He described it as a "nebula following the sting of Scorpius." A nebula is a cloud of gas and dust in space. Ptolemy's observation shows that this star cluster has been known and watched by people for a very long time.
Where to Find Messier 7
You can see Messier 7 in the constellation Scorpius. Scorpius is best seen in the summer sky in the Northern Hemisphere, or during winter in the Southern Hemisphere. The cluster is bright enough to be seen with the naked eye (without a telescope) from dark places, away from city lights. It looks like a fuzzy patch of light. With binoculars or a small telescope, you can see many individual stars within the cluster.
Stars in the Cluster
Messier 7 contains about 80 stars that are brighter than apparent magnitude 10. This means they are relatively bright when viewed from Earth. The brightest star in the cluster has an apparent magnitude of 5.6. The cluster is about 200 million years old, which is quite young for a star cluster.
Images for kids
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Broader view of M7, with the cluster at the center of the image
