Ancient, Distant Galaxy Found
BALTIMORE — Astronomers on Monday announced the discovery of the most distant galaxy known, a cluster of stars 15 billion light years away that formed long before the Earth and the sun.
“This is very unusual and very rare,†said Ken Chambers of Johns Hopkins University, one of the co-discovers. “We’re seeing something from before the Earth formed, possibly before our own galaxy, and when the universe was very different than today.â€
The distant galaxy, known as 4C41.17, is far too faint to be seen by the eye, but it emits a radio signal a billion times more powerful than the sun’s radio signal.
“It is one of the most powerful radio galaxies we know of,†Chambers said.
Although the galaxy was found by radio signals, its distance from Earth was established by analyzing the optical spectrum, or type of light, put out by the galaxy.
Chambers said the galaxy puts out a sharp optical signal of the type characteristic of hydrogen and carbon. The wavelength of the emission, however, is stretched by movement away from the observer.
This stretch causes the light color to shift toward red, the so-called “red shift.†By measuring this shift, astronomers can calculate the distance of the galaxy.
