Messier 5

StarDate

Lots of star clusters adorn the evening skies of summer. That’s because the glowing path of the Milky Way climbs high into the sky. It’s the combined glow of millions of stars that outline the disk of the Milky Way Galaxy. So not only does it contain lots of individual stars, it hosts many star clusters as well.

But a few clusters are far from the path of the Milky Way. One example is Messier 5. It’s in Serpens Caput – the head of the serpent – a region with not much around it.

M5 is a globular cluster – a big ball packed with several hundred thousand stars. Such clusters are scattered all across the sky. Some appear in the disk, but they’re not part of the disk – they loop high above and below it.

Globular clusters are the oldest members of the galaxy. And M5 is one of the oldest – 12 billion years or older. That means its original stars were born when the universe was only about one-tenth of its present age.

Any stars that were more massive than the Sun have burned out. So the remaining original stars are smaller and fainter than the Sun. There’s evidence that a second wave of starbirth rippled through M5 well after the cluster was formed. Some of these stars can still rival the Sun – the “youngsters” of an ancient star cluster.

Messier 5 is high in the south at nightfall. Through binoculars, it looks like a fuzzy star. A small telescope reveals some of the cluster’s individual stars.

Script by Damond Benningfield