"This galaxy is seen at a time when the Universe was only 500 million years old and yet it already has a population of mature stars," said Nicolas Laporte, an author of the research paper and researcher at the University College London. "We are therefore able to use this galaxy to probe into an earlier, completely uncharted period of cosmic history."

The question is when did the earliest stars form after the Big Bang? The team used infrared data of MACS1149-JD1 from the Hubble Space Telescope and the Spitzer Space Telescope to measure the observed brightness of the galaxy. The researchers came to the conclusion that the galaxy fits a model that has stars forming in the early universe just 250 million years after the Big Bang.

Scientists have long wondered when "cosmic dawn" occurred, which is when the first galaxies became bright and the universe was no longer cloaked in utter darkness. This new discovery will help researchers further determine when that might have been, and specifically, questions whether it could have occurred even earlier than scientists thought.