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.

2015 March 9
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Galaxy and Cluster Create Four Images of Distant Supernova
Image Credit: NASA, ESA, and S. Rodney (JHU) and the FrontierSN team; T. Treu (UCLA), P. Kelly (UC Berkeley), and the GLASS team; J. Lotz (STScI) and the Frontier Fields team; M. Postman (STScI) and the CLASH team; and Z. Levay (STScI)

Explanation: What are the unusual spots surrounding that galaxy? They are all images of the same supernova. For the first time, a single supernova explosion has been seen split into multiple images by the gravitational lens deflections of intervening masses. In this case the masses are a large galaxy and its home galaxy cluster. The featured image was captured last November by the Earth-orbiting Hubble Space Telescope. The yellow-hued quadruply-imaged Supernova Refsdal occurred in the early universe far behind the cluster. Measuring the locations and time-delays between the supernova images should allow astrophysicists to recover the amount of dark matter in the galaxy and cluster. With patience and luck, a fifth image of the supernova will also be recovered nearby in the next few years.

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