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.

2017 May 4
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The Perseus Cluster Waves
Image Credit: NASA, CXC, GSFC, Stephen Walker, et al.

Explanation: The cosmic swirl and slosh of giant waves in an enormous reservoir of glowing hot gas are traced in this enhanced X-ray image from the Chandra Observatory. The frame spans over 1 million light-years across the centre of the nearby Perseus Galaxy Cluster, some 240 million light-years distant. Like other clusters of galaxies, most of the observable mass in the Perseus cluster is in the form of the cluster-filling gas. With temperatures in the tens of millions of degrees, the gas glows brightly in X-rays. Computer simulations can reproduce details of the structures sloshing through the Perseus cluster's X-ray hot gas, including the remarkable concave bay seen below and left of centre. About 200,000 light-years across, twice the size of the Milky Way, the bay's formation indicates that Perseus itself was likely grazed by a smaller galaxy cluster billions of years ago.



Tomorrow's picture: bull's eye, crescent moon


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