If a tractor full of confetti was launched into the night sky and then beamed with a strobe light, it might look something like the Hubble Space Telescope image above.
It is, according to NASA, among the most colorful of deep space images ever captured by the 24-year-old telescope and it includes a massive cluster of galaxies — some 10,000 galaxies located 5 to 10 billion light years away. (That means that the ultraviolet light we’re seeing was emitted by these galaxies 5 to 10 billion years ago.)
The image, released Tuesday, is a composite of exposures taken over the last 10 years, constructed “from 841 orbits of telescope viewing time,” according to NASA. Captured by two cameras — Hubble’s Wide Field Camera 3 and its Advanced Camera for Surveys — it combines the full spectrum of colors available to Hubble, from near-infrared to ultraviolet light, represented in different colors. And it looks deep into a tiny region of the footprint of the sky.
“We picked the most boring patch of sky to study because there was nothing in the way,” said principal investigator Harry Teplitz.
For perspective, said Rogier Windhorst, a collaborator, who has worked on the Wide Field Camera 3 since 1998, imagine looking at the sky through a red coffee stirrer straw.
“Behind that tiny hole of the red stirrer straw, this is what you see — close to 20,000 galaxies,” he said. And the faintest star is as faint as a firefly on Earth as seen from the distance of the moon.
Before this, Hubble could see the most distant galaxies in this region — the red-shifted light from more than 10 billion light years away — along with those close to us. But the intermediate universe, which is seen in the ultraviolet, and which contains what Teplitz calls teenage galaxies, was less accessible to us. Until now.
This opens a vast new window of hot, young, previously-unseen stars. (Seen as baby blue in the image.)
“We’re filling in this gap in coverage of seeing the ultraviolet light in different stages of galaxy evolution,” Teplitz said. “And that’s important, because that’s when a lot of the galaxies in the universe formed.”
The big orange clumps are larger galaxies that likely started forming earlier — 7 to 8 billion years ago, Windhorst said. The faint blue dots are younger and more active.
“They start as faint blue clumps, and they grow and collide over time to form the bigger galaxies we see today,” Windhorst said. “This is cosmic star formation in its full glory — the Renaissance of cosmic star formation.”
Studying the structure of these individual galaxies in detail is going to be an exciting next step, Teplitz said. And this data makes that possible.
“We know from other studies that stars form in clumps of hot stars. How big the clumps are and where in the galaxy they are will tell us a lot about the evolution of galaxies.”