Data from the James Webb Space Telescope provides a glimpse of the galaxy we lived in before it was as big as it is today. Webb observed a galaxy called The Sparkler, which is analogous to the young Milky Way, when it was smaller and had only a handful of globular star clusters.
The Milky Way, the galaxy that contains Earth, is one of the oldest in the universe, being around 13.8 billion years old. Throughout its life, the Milky Way grew as more and more stars formed, until it reached its current mass of about 1.5 trillion solar masses and hosts about 200 dense globular clusters.
In contrast, the Sparkler galaxy is only 3% the mass of the Milky Way and only 24 globular clusters. However, this small galaxy grew by devouring nearby satellite galaxies and globular clusters, and is thought to eventually grow to equal the mass of the Milky Way.
“We appear to be witnessing, firsthand, the assembly of these galaxies as they build up their mass – in the form of dwarf galaxies and some globular clusters,” said lead author Duncan Forbes from Australia’s Swinburne University, quoted from Digital Trends (13/2). “We are excited about this unique opportunity to study the formation of globular clusters, and the baby Milky Way, when the universe was only 1/3 its current age.”
The Sparkler Galaxy is very far away, so its light takes billions of years to reach us. Researchers can see them better using a technique called gravitational lensing, which means they see them as they looked about 9 billion years ago.
