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  • Dark energy is the mysterious force driving the universe's accelerating expansion.

  • In an effort to understand it, scientists are planning to make the largest 3D map

  • of the universe to date. But before the galaxies can be plotted in three dimensions,

  • researchers had to capture an enormous area in 2D.

  • The result is the largest image of the night sky ever. And you can see the whole thing online.

  • It's hard to overstate just how impressive this single image is.

  • And the longer you look at it, the more you appreciate all of the

  • work it must have taken to make the whole thing possible.

  • It captures half of the sky

  • and more than a billion galaxies, depicted through over 10 trillion pixels.

  • Do you take a lot of pictures on your phone? Are you always running out of space for selfies or cat photos?

  • Well, in order to create a 10 trillion pixel image, you would have to stitch together 833,000

  • smartphone photos. Creating this map took more than 1,400 observing nights at three telescopes

  • over the course of six years.

  • Completely covering half the sky was a huge logistical challenge for the 200 researchers

  • involved in the project. For the telescopes to take the best images possible, the team

  • had to consider hours of darkness, weather, exposure time, the paths of planets and satellites,

  • the moon's brightness and locationthe list goes on.

  • Even with all those variables factored in, there was still the matter of creating

  • one homogeneous image. It's not as simple as just stitching them all togetherthe scientists

  • needed a way to minimize distortions caused by weather and atmospheric turbulence.

  • To do this they used supercomputers to compare their images with past sky surveys and select the

  • ones that most closely matched. Once they had the most accurate and uniform pictures

  • possible, they put them together and this is the result.

  • Taking in the two billion objects sprinkled over such an enormous backdrop can be a bit

  • overwhelming. To make navigating the stars more user-friendly, the researchers adapted

  • street-mapping software to suit their needs. They created a tool called the Legacy Sky Survey Viewer.

  • Users can jump to an object if they know its name, or toggle filters to

  • help find specific object types. They can also turn on overlays to see constellations,

  • or which galaxies the researchers plan to further study for the 3D map.

  • While the navigation tool was originally designed to help researchers more easily find issues with their data, the

  • scientists were surprised at how powerful it was.

  • One said that suddenly the data just felt a lot more real and it changed the way the

  • team interacted with it. Another researcher figured that if it impacted them so much,

  • maybe the public would want to see it too. So they made it available to all of us online,

  • and that means that anyone could potentially discover new examples of rare objects, or

  • even entirely new ones. Considering how awe-inspiring this 2D map is, it's amazing to think it's

  • a stepping stone to a bigger goal. It was created to identify which galaxies and quasars

  • the Dark Energy Spectroscopic Instrument, or DESI, will survey.

  • This instrument will be able to measure the distances to objects located up to 12 billion

  • lightyears away. DESI will also measure the redshift of these objects to determine how

  • fast they're moving away from us. With this information, astronomers and cosmologists

  • will be able to create a 3D map of a huge portion of the universe and tease out more

  • information about how dark energy shapes the cosmos. If you're like me and plan to set

  • aside at least a full day to marvel at this image, just remember that the best may still

  • be yet to come.

Dark energy is the mysterious force driving the universe's accelerating expansion.

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This Is the Largest Map of Our Universe Ever Created

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    林宜悉 posted on 2021/03/12
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