"Of course there is a range," said Mark Dickinson of the National Optical Astronomy Observatory in Tucson, Arizona. "Some galaxies would have formed more quickly, and it might just be that we're seeing an extreme example of that."
But, Dickinson continued, "it's a sample of one. You can ask [in light of current theories] how likely is it that you'd find a galaxy like this? The answer is that it's not very likely, not that it couldn't exist."
At the Edge of Observation
The HUDF-JD2 galaxy is located in a tiny patch of sky called the Hubble Ultra Deep Field.
No one knows for sure how far away the galaxy lies because the discovery is pushing the very limits of telescope technology.
"It's definitely a galaxy, it's definitely very distant, there's no question about that," Dickinson said. "Is it at the very edge of the observable universe, or not quite that far?"
Hubble cannot see the galaxy in visible light, but this non-observation may hold important information.
"The fact that we don't see it in the deepest optical images ever taken is one of the reasons we believe it's as old as it is," Dickinson explained.
As the universe expands, light is stretched and shifted to longer, redder wavelengths. The newfound galaxy's visual wavelengths appear to have been so reduced that they were absorbed by space hydrogen as they traveled the billions of light years toward Earth.
The galaxy was spotted via Hubble's infrared images and by an infrared camera on the Very Large Telescope at the European Southern Observatory.
Such state-of-the-art equipment enabled astronomers to discover the galaxy, but the big baby's exact distance will likely remain a mystery until the next generation of telescopes emerges.
"We're at the frontiers of what we can do with our existing telescopes," Caltech's Ellis explained.
Ellis spoke from an Aspen, Colorado, meeting where Caltech is collaborating with other institutions on the construction of a 98-foot (30-meter) telescope.
The instrument would have ten times the power of the world's largest telescopethe 33-foot (10-meter) instrument at the W.M. Keck Observatory atop Hawaii's Mauna Kea volcano.
The discovery of the new galaxy provided another compelling reason to develop telescopes that can peer further back into the universe's distant past.
"It's like crossing the ocean and meeting a lone seagull, a forerunner of land ahead," Ellis said. "There is now every reason to search beyond this object for the cosmic dawn when the first such systems switched on."
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