See The New Map Of One Billion Galaxies That Took Six Years To Create

There is no “blanket of stars.” The night sky we all see has infinite depth. From Earth at night with naked eyes we mostly see the stars of our own galaxy, the Milky Way, but beyond is the entire universe. Using powerful telescopes it can be navigated and known. All you need is a map—and they keep getting better.

This week saw the release of the largest two-dimensional map of the sky ever made. It comes from the tenth data release from the DESI Legacy Imaging Surveys, a six-year survey of nearly half the sky using telescopes at Kitt Peak in Arizona and the Cerro Tololo Inter-American Observatory in Chile.

The Legacy Surveys—which can be explored online—is designed to create the most comprehensive map of the sky possible to help astronomers understand how the universe has expanded over the last 12 billion years. That’s critical to understanding “dark energy,” an unknown force that appears to be accelerating the universe’s expansion.

The new data mostly comes from the Dark Energy Camera (DECam) on the Víctor M. Blanco 4-meter Telescope at CTIO in Chile. Its observations of the southern extragalactic sky—areas away from the Milky Way’s disk—will help astronomers identify roughly 40 million target galaxies.

Overall the six-year effort has used one petabyte (1,000 trillion bytes) of data and 100 million CPU hours on one of the world’s most powerful computers.

As well as expanding the canvas of the sky map to 20,000 square degrees—nearly half the sky—this new version adds an infrared light filter. “The addition of near-infrared wavelength data to the Legacy Survey will allow us to better calculate the redshifts of distant galaxies, or the amount of time it took light from those galaxies to reach Earth,” said Alfredo Zenteno, an astronomer with NSF’s NOIRLab and principal investigator of DECam eROSITA Survey (DeROSITAS), in a statement.

That will make the map more useful for radio astronomers who find powerful signals in space and need to pinpoint which clusters of galaxies and active supermassive black holes they originate from.

However, it’s also hoped that the new map will be used by the public. “Anyone can use the survey data to explore the sky and make discoveries,” said Arjun Dey, an astronomer with NSF’s NOIRLab, in a statement. “We hope that in a few years the Legacy Surveys will have the most complete map of the entire sky, and provide a treasure trove for scientists well into the future.”

Wishing you clear skies and wide eyes.