In today's image, we see the galaxy cluster known as Abell 370. The arcs in the photo are distorted images of distant galaxies beyond the cluster that have be affected by gravitational lensing. When light passes through a region of large mass, its path is changed because of the way the mass distorts the spacetime around it. This was a prediction of Einstein's Theory of General Relativity from over 100 years ago.

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This Podcast is an authorized New Media Mirror Site for APOD. You can access the image and website directly at: Astronomy Picture of the Day. You can use the archive link below the image to select the photo corresponding to the date of this podcast.

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