When a white dwarf accretes too much material or a massive star expends its nuclear fuel, the star’s death throes yield an explosion—a supernova—so intense that it often outshines the star’s host galaxy. Within the past several years, astronomers have recognized a new class of supernovae: superluminous supernovae (SLSNe), which can outshine their conventional siblings by a factor of 100 or more.1 

The most radiant SLSN of all was spotted last June by the Ohio State University–led All-Sky Automated Survey for Supernovae (ASAS-SN, pronounced “assassin”), according to an analysis by an international team led by Subo Dong (Peking University) and Krzysztof Stanek (Ohio State).2 The object, dubbed ASASSN-15lh, has double the luminosity of the runner-up SLSN. And it’s a rather mysterious beast indeed.

Traditionally supernovae are found in targeted searches: Observers look for the abrupt appearance of explosions in a specific set of large galaxies that are periodically...

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