Globular clusters are like living fossils. It’s like discovering a community of people who’s been around since the Stone Age. Some stars here have been shining for 12 billion years, more than twice as long as the sun and that helps to put an age to the Milky Way. 

 

 

 

Globular clusters are part of our galaxy. They orbit our galaxy, in some sense, they are tracers of our galaxy itself. And so by the fact that the globular clusters are so old, it suggests that the galaxy is so old. 

 

 

 

So globular clusters tell us something extraordinary. Our galaxy is one of the oldest objects in the cosmos. It’s been around almost since the beginning of the universe, at least 12 billion years. The stars in these clusters also reveal/ that when it first formed, the chemistry of the galaxy was very different from how it is today. 

 

 

 

We can measure the chemical properties of those stars. Turns out, they have very low abundances of the heavy elements, things like iron, are very rare in globular cluster stars compared to a star like the sun. 

 

 

 

What’s true of / globular clusters is true of the early galaxy. It would have been a far less colorful place, lacking heavy elements which color the nebulae and supernovae remnants we see today. But more importantly, it would have been a galaxy without life. It took billions of years for stars to form enough heavy elements for the evolution of life to begin anywhere in the Milky Way.