July 2, 2000
In the time it took you to read this, the Earth moved another thousand miles through space. You are not standing still. You never have been.
Gamma-Ray Burst: A Milestone Explosion
Birthday · July 2, 2000
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APOD published July 2, 2000. Full image credits are on the original APOD entry below. A publication-date match, not a photo taken on your date. Independent of NASA.
Gamma-Ray Bursts (GRBs) were discovered by accident. Thirty three years ago today, satellites first recorded a GRB. The data plotted here show that the count rate of the satellite gamma-ray instrument abruptly jumped indicating a sudden flash of gamma-rays. The Vela satellites that detected this and other GRBs were developed to test technology to monitor nuclear test ban treaties. With on board sensors they watched for brief x-ray and gamma-ray flashes, the telltale signatures of nuclear explosions. As intended, the Velas found flashes of gamma-rays - but not from nuclear detonations near Earth. Instead, the flashes were determined to come from deep space! Dubbed "cosmic gamma-ray bursts" they are now known to be the most powerful explosions originating in distant galaxies. What could power a gamma-ray burst?