National Astronomical Observatory of Japan

A Journey Through the Milky Way


It has been said that on the evening of the Tanabata Festival (The Star Festival), many Kasasagi birds (magpies) spread their wings and make a bridge so that Orihime (The Weaving Princess Star) and Hikoboshi (The Cowherd Star) can cross the Amanogawa (Milky Way, literally “River of Heaven.”) It was Galileo Galilei that who first looked up at the heavens using a telescope. He revealed that the band of light (Milky Way) across the night sky is a collection of countless stars. In the Amanogawa, not only stars exist but also celestial bodies such as “diffuse nebulae” which shine red and the “dark nebulae” that spread-out in black.

In this video, we will go through the Milky Way Galaxy calculated with the supercomputer “ATERUI.” Orihime and Hikoboshi might also see this scene while crossing the bridge of Kasasagi.

Milky Way Galaxy

What the Milky Way really is, is a disked shaped collection of stars seen from the side. Looking at the Milky Way Galaxy from outside, stars form a bar like shape in the center of the galaxy, and it is thought that from the ends of the bar spiral arms extend throughout the whole disk. Galaxies that have this structure are called “barred spiral galaxies.”

In this simulation, we created the Milky Way Galaxy in a more realistically way by performing calculations considering basic physical process of galactic evolution, such as the gravitational interactions of the stars and the gases; the movement motion and evolution of the interstellar gases; and the formation of stars and its effect on the surroundings.

Virtual Reality (VR) Video

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Video Data

Computer UsedCray XC30 “ATERUI”
Time Scaleabout 100 - 1000 million years
Spatial Scaleabout 500,000 light-years
Calculations byJunichi Baba (now at NAOJ; Tokyo Tech and Ehime University at the time of the calculations and analysis)
CreditsJunichi Baba, Hirotaka Nakayama, Four-Dimensional Digital Universe, NAOJ

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