Astronomers have detected a small galaxy 12.3 billion light-years from Earth - the most distant object ever seen - and say they are on the brink of seeing things even farther away and closer to the big bang beginning of the universe.
"We've already got some candidate objects that are even farther away," said Esther M. Hu, a University of Hawaii astronomer and co-discoverer of the most distant object. "We are looking about 94 percent of the distance back to the big bang."The discovery was first announced in Science News, a weekly journal of research reports. The journal is to publish the story on Saturday.
The big-bang theory holds that the universe started with a huge explosion and has been expanding ever since. In the billions of years since, the hydrogen and helium in the big bang have been processed through stars to form other chemicals. Just when the big bang happened is controversial, but most astronomers say it was about 13 billion years ago.
Just six weeks ago, another team of astronomers found a small galaxy about 12.2 billion light-years away to establish a most-distant mark. Both teams used the Keck telescopes in Hawaii. A light-year is the distance light travels in a vacuum in one year, about 5.8 trillion miles.
"The records for most distant galaxies have become really fragile," said Bruce Margon, a University of Washington astronomy professor. "Once they would stand for six or seven years. Now it changes in a matter of months."
Margon said the latest discovery is important because it continues to push back the time when it is known that stars and galaxies formed after the big bang, giving more understanding of the developmental history of the universe.
Hu and her colleagues, Lennox L. Cowie of Hawaii and Richard G. McMahon of the University of Cambridge, England, sighted the distant galaxy by analyzing a particular wavelength of light emitted by hydrogen atoms.
This technique, said Hu, will enable the group to probe even farther back in time and distance.
One way astronomers measure distance and time is by a value called the redshift. This is the amount that a wavelength of light has been stretched, or shifted, by the expanding universe. The new most-distant galaxy found by the Hu team is at a redshift of 5.64. This is about 60 million years earlier than the previous mark, which was a redshift of 5.34.