Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2022 July 6
The featured image shows a map of star motions in the 
Milky Way galaxy with red, mostly on the left, meaning stars
are moving away us. Blue, on the right, shows stars there
are mostly toward us. 
Please see the explanation for more detailed information.

Milky Way Motion in 3D from Gaia
Credit & License: ESA, Gaia, DPAC; Text: Ata Sarajedini (Florida Atlantic U., Astronomy Minute podcast)

Explanation: Our sky is alive with the streams of stars. The motions of 26 million Milky Way stars are evident in the featured map constructed from recent data taken by ESA's Gaia satellite. Stars colored blue are moving toward us, while red indicates away. Lines depict the motion of the stars across the sky. The large blue on the left and red areas on the map's right give the overall impression that stars in the Milky Way are rotating around the center. However, there is a region near the middle -- caused by our own Sun's motion relative to a rigidly-rotating central Galactic bar -- that seems to reverse it. Understanding details about the motion of stars is helping humanity to better understand the complex history of our Milky Way galaxy and the origin of our Sun.

Tomorrow's picture: open space

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