Squinting deep into the universe, the Hubble Space Telescope has picked out what may be the most distant galaxy yet found, observed as it appeared about 380 million years after the big bang, astronomers said Wednesday. This potential record-breaker is one of seven newly discovered galaxies formed more than 13 billion years ago, right near the cosmic dawn, the era when the first big galaxies formed.
“These galaxies are so young that they existed before many of the atoms in our bodies existed,” said James Bullock, a University of California at Irvine physics and astronomy professor who was not involved in the study.
A team of scientists led by Caltech astrophysicist Richard Ellis used NASA’s famous orbiting telescope to look deep into a slice of sky known as the Hubble Ultra Deep Field. The researchers hoped to pick up signs of distant galaxies as close to the edge of the universe as Hubble could see, because as they look deeper into space, they’re also looking farther back in time.
To determine a galaxy’s age, scientists measure what’s known as redshift of the light they see coming from it: As the universe rapidly expands and the galaxies speed up, the light from those galaxies is stretched into longer, and redder, wavelengths. From the degree of this redshift, astronomers can determine how fast an object is moving away, and thus how far away it must be. The more extreme the redshift, the farther it must have traveled — and thus the older Hubble’s snapshot of it is.
Astronomers know that universe began in a big bang roughly 13.7 billion years ago because they see evidence of the event in the cosmic background radiation that permeates the universe. They have a good sense of what it looked like in its adolescence and adulthood, because telescopes can look far enough into space to capture snapshots millions and billions of years into the past.