We recently reported that scientists working with the Hubble Space Telescope have spotted the oldest known galaxy in the universe, measuring in at a whopping 13.3 billion years old. There are many ancient galaxies popping up as we point our telescopes back in space and time, and learning about them can help visualize the way stars form.

According to Phys.org, stars form when massive clouds of dust and gas coalesce around an origin and continue to accumulate mass. When the cloud gets heavy enough, it collapses inward and creates great pressure and energy, beginning the series of nuclear reactions that fuel a star.

Stars form galaxies, which group together to form clusters containing billions of suns. There are many different types of stars in these galaxies, some of which are extremely old.

The recently discovered galaxy showed up in the Hubble’s images to reveal a large cloud of ionized hydrogen, which had been cloaking the light emanating from the galaxy by absorbing the stars’ ultraviolet radiation. The cloud of hydrogen surrounding the galaxy provides fuel for the stars to keep their reactors running and continue to grow.

The amazing thing we’ve learned from studying old galaxies is that all of the materials used to form stars are perpetually recycled – the gas collapsing inward on itself to create new stars was likely blasted out into space when a previous star exploded in a supernova.

Ancient galaxies are fascinating, and they can reveal many secrets about the evolution of our universe as we know it today.