Hydrogen, the most abundant element in the cosmos, has never looked so spectacular.
Researchers using the world's largest radio telescopes in Germany and Australia have created an unprecedented map of the Milky Way's hydrogen atoms. Titled HI4PI, the image is the result of 10 years of work that included more than a million observations and the collection of billions of individual data points. The final result was painstakingly stitched together to show both hemispheres of the night sky.
"What it gives us is a map of the sky in hydrogen that normal telescopes, normal optical telescopes, can't see," Australian professor Lister Staveley-Smith from the International Centre for Radio Astronomy Research (ICRAR) told ABC. "It's very important to understand the structure of gas in our own galaxy and the amount of gas in our own galaxy, its dynamics, in order that we can study the past evolution of the Milky Way and its likely future evolution."
In addition to piecing the hydrogen puzzle together, the researchers also had to filter out human-made distortions that would otherwise have skewed the results.
“Radio ‘noise’ caused by mobile phones and broadcast stations pollute the faint emissions coming from stars and galaxies in the universe,” Jürgen Kerp, one of the researchers behind the map and an astronomer with the University of Bonn, said in a statement. “So sophisticated computer algorithms have to be developed to clean each individual data point of this unwanted human interference.”
The final map reflects hydrogen gas traveling at different velocities in relation to Earth, with purple/blue representing approaching atoms and green/orange representing receding. Corresponding brightness indicates concentration. As for the double splotches in the bottom right that look a bit like New Zealand, those are the Magellanic Clouds, two dwarf galaxies that orbit around the Milky Way.
Scientists hope the incredible detail offered by the map helps them understand how the Milky Way was formed and how other galaxies and stars are born as well.
“Essentially, hydrogen is the element of the universe,” Kerp told Motherboard's Ben Sullivan. “Formed within the first three minutes after the Big Bang [it’s] the material that eventually forms stars. Thus, HI4PI 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].”
Check out a video of the two hemispheres from the map, set to some lovely classical music, rotating below: