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.

2023 July 12
A spiral galaxy is shown with a yellow center, blue rings and spiral arms,
and dark brown and red dust. The surrounding dark field contains both local
stars and more distant galaxies. 
Please see the explanation for more detailed information.

Rings and Bar of Spiral Galaxy NGC 1398
Image Credit: Mark Hanson; Data: Mike Selby

Explanation: Why do some spiral galaxies have a ring around the center? Spiral galaxy NGC 1398 not only has a ring of pearly stars, gas and dust around its center, but a bar of stars and gas across its center, and spiral arms that appear like ribbons farther out. The featured deep image from Observatorio El Sauce in Chile shows the grand spiral galaxy in impressive detail. NGC 1398 lies about 65 million light years distant, meaning the light we see today left this galaxy when dinosaurs were disappearing from the Earth. The photogenic galaxy is visible with a small telescope toward the constellation of the Furnace (Fornax). The ring near the center is likely an expanding density wave of star formation, caused either by a gravitational encounter with another galaxy, or by the galaxy's own gravitational asymmetries.

Tomorrow's picture: open space


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