This is Hubble’s rendition of a smashed rock in someone’s driveway. LOL! It kind of looks like that… Globular clusters are large aggregations of stars, that are gravitation-ally bound, not ‘Big gobs of spit!’ Our galaxy contains about 150 globular clusters. It is estimated that the Andromeda galaxy may have as many as 500!
They orbit the central hub of our galaxy, and can contain a million or more stars. Since they orbit outside of our galaxy, the above photograph lies to us in the sense that some stars you see here, are just foreground stars within our own galaxy… They orbit within a zone approximately 130,000 light years from us! Here is the URL for a fascinating read on globular clusters: https://en.wikipedia.org/wiki/Globular_cluster
Above, is an image of NGC 288 in the constellation ‘Sculptor’… It’s a very ancient cluster with mostly older yellow stars. The appearance of ‘a ball of stars’ is an optical illusion created by the vast distances and closer proximity of the stars to each other. If you were within the cluster you would see a lot of stars, but they would not appear in the sky as a ball… In fact, stars nearer the center are so close together as to be less than a light year apart, (about the size of our solar system). Further out, where less gravity exists, stars are further apart from one another, giving a ‘fanning out’ appearance of stars.
Starting with the above picture onward, I made these pictures in ‘Microsoft Telescope’, just by choosing to save the view to file, from the ‘View’ menu. I first turned off all the constellation lines,center courser etc. until just the image shows when you hit F-11. This is a great program, absolutely FREE from Microsoft, and will actually follow the sky in real time from your latitude, if you punch your city in… Very user friendly, with controls, or your mouse wheel if you have one, to zoom in or out.
Just upper right center is how M4 (The Messier Catalog originally representing 104 objects), can just be typed in the search field to slew you to its location. Talk about foreground stars! Bottom left, the super-giant star ‘Antares’ glares at as from the constellation ‘Scorpius’, and is a mere 550 light years away.
This star has a radius of 883 suns, yet only about 15 times the mass of our sun, so it is very lite in weight; comparable to that of a giant hot air balloon, yet burns with 10,000 times the visible luminosity of our sun, which conjures a strange image indeed! Here’s more about Antares: https://en.wikipedia.org/wiki/Antares
Enjoy the slide show I put together on Globular clusters…