The Hubble Space Telescope has detected light from a small galaxy emitted just 500 million years after the big bang, a crucial and difficult-to-study era when the universe was very young, scientists reported.

Scientists were able to see the galaxy because gravity from a massive galaxy cluster situated between it and Hubble acted as a lens, bending the light from the "incredibly faint" galaxy and magnifying it about 15 times, said Johns Hopkins astronomer Wei Zheng, co-author of the study in the journal Nature.

Zheng discovered MACS 1149-JD in November and he and fellow members of the Cluster Lensing and Supernova survey with Hubble, or CLASH, team spent several months "convincing ourselves it was a real case," he said. The galaxy likely began its light journey toward Hubble about 13.1 billion years ago, when the universe was a mere 500 million years old, Zheng said. The team was able to estimate its likely mass (less than 1 percent that of the Milky Way) and shape (compact, compared with similar galaxies observed later in the universe's 13.7 billion-year history).

Astronomers are excited by the prospect of finding similar galaxies because they could help reveal the universe's early history, said Avi Loeb, a Harvard astronomer. "It's like having an ultrasound picture of a baby and photos of a person as an adult. We want to understand what happens in between."