Early Wednesday morning, a spot of light just barely visible to the human eye (about fifth magnitude in astronomical parlance) appeared in the constellation Bootës. Astronomers say it was the toasted remains of one of the most titanic examples yet of the explosions known as gamma-ray bursts. News about the burst, in a galaxy seven billion light years away, began circulating by e-mail in the astronomical community when it was detected by NASA's Swift satellite on March 19.

Gamma ray bursts are some of the most violent and enigmatic events in nature. Astronomers surmise that they might mark the implosion of a massive star into a black hole, or the collision of a pair of dense neutron stars.

The visible glow from this burst, said Neil Gehrels of NASA's Goddard Space Flight Center, was 10 million times as bright as a supernova at that same distance. The universe is some 14 billion years old, which means that the news of this cataclysm has been on its way to us for half the age of the universe. Whatever stars went to their grave then have been dead since before the Sun and Earth were born.