Researchers from the National Astronomical Observatory of Japan (NAOJ) and Tokyo University have created a three-dimensional image of the Milky Way -- reportedly the first of its kind. The image depicts a disk-shaped galaxy with a large deformity in one area, and it indicates the presence of five spiral arms as opposed to the six commonly believed to exist. The results of the research were presented at a meeting of the Astronomical Society of Japan in Wakayama City on March 28.

3D image of Milky Way

(The area on the bottom-left is deformed. The red area represents neutral hydrogen gas, the green represents hydrogen molecular gas, and the area at bottom is blank due to a lack of data.)

Because interstellar dust interferes with attempts to observe the galaxy’s visible light, the researchers focused on studying radio waves emitted by hydrogen, which is abundant in our galaxy. A variety of existing observation data from radio telescopes in Europe, the Americas, and Australia was collected, and after 6 years of analyzing the quantities and movement of hydrogen gas, an image of the three-dimensional structure of the galaxy emerged.

Gas quantities were calculated from the strength of radio waves emitted by hydrogen gas, and gas locations were obtained from calculations based on the galaxy’s rotational speed. Using the resulting distribution map of gas density, a computer was able to recreate the shape of the galaxy.

"The image can help provide a visual understanding of the cosmos that we live in," says NAOJ Nobeyama Radio Observatory researcher Hiroyuki Nakanishi. "I hope it can play a role in education."

The Milky Way is estimated to be roughly 65,000 light years in radius and 10,000 light years thick.

[Sources: Mainichi Shimbun, Asahi Shimbun, NRO press release (with high-resolution images)]