Lost in Geek

The Hubble space telescope, apparently doomed to no more than about three more years of full observation because of NASA's decision to no longer service it, has done it again.

The farthest object in the Universe yet detected has been seen by scientists using the Hubble and Keck telescopes.

It is so distant its light must have set out when the Universe was just 750m years old to reach the Earth now. ...

"The new object is a small and compact system of stars," said Professor Ellis. "It's about 2,000 light-years across; our own galaxy by comparison is about 60,000 light-years across.

"It is forming stars prodigiously and is a very energetic source, so it may be an example of an object from that early time [just after the "Dark Ages"] that is the first of its kind to form in the Universe."

The "Dark Ages" is the period after the Big Bang when the universe had cooled enough for hydrogen atoms to form (before that, heat energy would rip atoms apart) but before the first stars "turned on," meaning the universe was without light. No one is sure how long this period lasted, but the farther away a light source is, the earlier in the universe it formed: Light travels at a finite speed, so the farther away a light source is, the longer a time that light took to get to Earth, and so the farther back in time from now that light must have been generated.

The object was discovered using "gravitational lensing," an effect first predicted by Einstein. Light spreads out, so the farther away any light source is, the dimmer it appears. But light is bent by gravity, which is related to mass. So light coming from behind a very massive object - like, in this case, a star cluster - can be bent and refocused, as if by a lens, making the object appear brighter and so easier to detect.