By Rafi Letzter
Ancient, massive galaxies haunting the dusty reaches of our universe have been in hiding, invisible to the eyes of the famous Hubble Space Telescope. But now, astronomers sifting through infrared data have discovered 39 of them — lurking in strange places from the early universe where (and when) the night sky would look very different from our own.
If you were to approach one of these long-ago galaxies while inside a spacecraft, it would probably be at least recognizable to you: stars you could see with the naked eye, swirling dust, a big black hole at the center. And if you were to somehow appear there today, it would likely look quite different than it did more than 11 billion years ago, in the early history of our universe. But the light reaching Earth in 2019 from these massive, distant galaxies had to travel so far that it’s billions of years old, showing us what that part of the universe looked like in its first 2 billion years of existence. And the light is so altered that the Hubble — built to see in ultraviolet, visible and near-infrared light — couldn’t see it at all.
That’s because these faraway galaxies, like most faraway things in our universe, are speeding away from us — a consequence of dark energy driving the expansion of space. As Live Science has previously reported, light from objects speeding away from us gets stretched into longer, redder wavelengths. And these superdistant galaxies are speeding away so fast, according to the researchers who discovered them, that the ultraviolet and visible light they emitted has shifted entirely into the long “submillimeter” wavelength range that even Hubble can’t detect.
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