This Breathtaking Map Traces Hydrogen Throughout the Milky Way

Scientists have made the most detailed map of our home galaxy’s hydrogen currently possible

galaxy map
A new map reveals the most detailed picture of hydrogen atoms in the Milky Way ever made. Benjamin Winkel and the HI4PI collaboration

When it comes to the atoms and elements of the universe, hydrogen rules. It makes up nearly everything—from stars to galaxies. And by tracking it around the night sky, scientists have learned a lot, even details about the origins of the cosmos. Now, an international team of scientists have pieced together data gathered from two of the world’s most powerful telescopes to create the most detailed map of hydrogen atoms in the Milky Way to date.

Radio telescopes are critical tools for mapping the night sky, but even the most powerful ones can only glimpse a tiny piece of the observable universe. So in order to make this map, it took teams of researchers working on opposite sides of the world joining forces, George Dvorsky reports for Gizmodo.

"We've kind of just put the data together from both hemispheres, a bit like putting maps of our own world together from the Northern Hemisphere and the Southern Hemisphere and picturing the globe for the first time," Lister Staveley-Smith, a researcher from the International Center for Radio Astronomy Research (ICRAR) who ran the project, tells Emily Piesse for the Australian Broadcasting Corporation.

Half of the team on this project were based out of Australia’s CSIRO radio telescope, while the others pored through data gathered by the Max-Planck radio telescope in Germany. But even with two teams covering each hemisphere, it took millions of observations and ten years of work to stitch this map together, Dvorsky reports.

Neutral hydrogen atoms may be common and easy to detect, but making a map of this scale took some serious effort. Not only did it take time to scan every inch of the observable skies from both the northern and southern hemispheres, but the researchers also needed to filter out any distortions in the data that may have been caused by human technology or simple glitches, Ben Sullivan reports for Motherboard.

“Radio ‘noise’ caused by mobile phones and broadcast stations pollute the faint emissions coming from stars and galaxies in the universe,” Jürgen Kerp, an astronomer with the University of Bonn, says in a statement. “So sophisticated computer algorithms have to be developed to clean each individual data point of this unwanted human interference.”

For the scientists, however, the years of effort have paid off. The end result maps trails of neutral hydrogen atoms across the Milky Way and illuminates the massive, gaseous structures that link the galaxy’s stars. Now that these trails have been traced in great detail, astronomers can better understand the chemical makeup of our own galaxy as well as more distant ones, Sullivan reports.

“Essentially, hydrogen is the element of the universe,” Kerp tells Sullivan. “Formed within the first three minutes after the Big Bang [it’s] the material that eventually forms stars. Thus, [the map] allows us to study the evolution of the Milky Way galaxy from pure hydrogen gas to stars. The basic evolutionary steps of the star formation are well established today, but the links between them we just start to explore [sic].”

With the map and the data used to make it being freely offered to other scientists, it could soon help blaze new trails in how astronomers understand our universe.

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