In terms of discoveries, astronomers could well call this the year of the galaxy, so many celestial surprises are they stumbling across as they peer at the farthest reaches of the universe.
In the past two months alone, astronomers have been crowing over as many new finds: the most ancient spiral galaxy ever seen, and the oldest known galaxy in the universe.
At 10.7 billion years old the spiral, announced on July 18 by researchers at UCLA and the University of Toronto, is not the oldest galaxy in the universe. That honor goes to the earlier find, a galaxy 12.91 billion light years away discovered in June by Japanese astronomers, and possibly to researchers on an earlier find from Arizona State University. (The latter claim to have found one slightly older, but experts said the date on the Japanese discovery seems more solid.)
Either way, the spiral is notable because such galaxies were thought not to exist back when the universe was so young. It is much too tailored, said Alice Shapley, a researcher with the department of physics and astronomy at the University of California Los Angeles and a co-author of the study, whose findings were reported in Nature on July 18.
“The vast majority of old galaxies look like train wrecks,” said Shapley in a UCLA statement. “Our first thought was, why is this one so different, and so beautiful?”
The spiral galaxy, dubbed with the glamorous epithet of BX442, dates back to when the universe was but three billion years old, which is before anything with such definition should have formed. Something from that far back should still have been clumpy and irregularly shaped, the statement said, not strikingly symmetrical like the Milky Way.
“Seeing this galaxy amongst the irregular, young galaxies of that epoch is like seeing a fully-formed adult in a room of grade-school children,” said David Law, a University of Toronto professor and another lead author on the study, in the statement. “The fact that this galaxy exists is astounding. Current wisdom holds that such grand-design spiral galaxies simply didn’t exist at such an early time in the history of the universe.”
Only slightly less impressive is the June discovery by Japanese astronomers that the Associated Press reported last month. Scientists with the National Astronomical Observatory of Japan made the discovery from their telescopes atop Mauna Kea, Hawaii, the AP said.
Not so well formed as the spiral, this one was more in line with what is expected from the earliest years of the universe, which is thought to be 13.7 billion years old, starting at the time of the Big Bang.
About a week before the Japanese team made its announcement, astronomers at Arizona State University (ASU) said they had found a galaxy that’s 13 billion years away.
“This image is like a baby picture of this galaxy, taken when the universe was only five percent of its current age,” ASU astrophysicist James Rhoads said in a statement from the university’s School of Earth and Space Exploration, where he is a professor. “Studying these very early galaxies is important because it helps us understand how galaxies form and grow.”
The computer simulation below shows clumps of whirling star matter flinging themselves around, crashing into one another and bouncing off, swirling into ever more defined spiral shapes. Ultimately, it’s the stuff we are made of.