Hubble telescope captures spectacular image of globular cluster

by Colin Stuart

IC 4499: A globular cluster’s age revisited Globular cluster IC 4499 as seen by the Hubble Space Telescope. [credit: NASA/ESA]

This stunning image of globular cluster IC 4499 was recently taken by the Hubble Space Telescope (click image to see larger version).

A globular cluster is an ancient group of stars all packed into a reasonably small region of space. Their compact nature means that if you were on a planet orbiting one of the stars in the group, you would likely see tens of thousands of stars in your night sky. It would never get truly dark on your world – even at midnight the glow from starlight would make it like dusk or dawn here on Earth.

Our Milky Way galaxy is orbited by at least 150 globular clusters, including IC 4499. By studying the way these clusters move, astronomers can probe the amount of mass our galaxy contains. The more mass it has, the stronger gravitational pull it has on the clusters. This is important because the Milky Way seems to have a lot more matter in it than we can see with our telescopes. Most of the galaxy is thought to be made up of ‘dark matter’, the true nature of which is still unclear.

This particular global cluster puzzled astronomers because previous observations seemed to suggest it was a lot younger than some of the other globular clusters that orbit around the galaxy. However, more recent Hubble observations have shown it is actually about 12 billion years old – about the same age as its companions.