Rates and Potential Effects On Life On Earth
All the bursts astronomers have recorded so far have come from distant galaxies and have been harmless to Earth, but if one occurred within our galaxy and were aimed straight at us, the effects could be devastating. Currently orbiting satellites detect an average of about one gamma-ray burst per day. The closest known GRB so far was GRB 031203.
Measuring the exact rate is difficult, but for a galaxy of approximately the same size as the Milky Way, the expected rate (for long GRBs) is about one burst every 100,000 to 1,000,000 years . Only a small percentage of these would be beamed towards Earth. Estimates of rates of short GRBs are even more uncertain because of the unknown degree of collimation, but are probably comparable.
Gamma-ray bursts are thought to emerge mainly from the poles of a collapsing star. This creates two oppositely-shining beams of radiation shaped like narrow cones. Planets not lying in these cones would be comparatively safe; the chief worry is for those that do.
Depending on distance, a gamma flash and its ultraviolet radiation could damage even the most radiation resistant organism known, the bacterium Deinococcus radiodurans. These bacteria can endure 2,000 times more radiation than humans. Life surviving an initial onslaught would have to contend with a potentially lethal aftereffect, depletion of the atmosphere's protective ozone layer by the burst.
Read more about this topic: Gamma-ray Burst
Famous quotes containing the words rates, potential, effects, life and/or earth:
“In the U.S. for instance, the value of a homemaker’s productive work has been imputed mostly when she was maimed or killed and insurance companies and/or the courts had to calculate the amount to pay her family in damages. Even at that, the rates were mostly pink collar and the big number was attributed to the husband’s pain and suffering.”
—Gloria Steinem (20th century)
“Not many appreciate the ultimate power and potential usefulness of basic knowledge accumulated by obscure, unseen investigators who, in a lifetime of intensive study, may never see any practical use for their findings but who go on seeking answers to the unknown without thought of financial or practical gain.”
—Eugenie Clark (b. 1922)
“Trade and commerce, if they were not made of India-rubber, would never manage to bounce over the obstacles which legislators are continually putting in their way; and, if one were to judge these men wholly by the effects of their actions and not partly by their intentions, they would deserve to be classed and punished with those mischievous persons who put obstructions on the railroads.”
—Henry David Thoreau (1817–1862)
“I feel my belief in sacrifice and struggle getting stronger. I despise the kind of existence that clings to the miserly trifles of comfort and self-interest. I think that a man should not live beyond the age when he begins to deteriorate, when the flame that lighted the brightest moment of his life has weakened.”
—Fidel Castro (b. 1926)
“In short, I am convinced, both by faith and experience, that to maintain one’s self on this earth is not a hardship but a pastime, if we will live simply and wisely; as the pursuits of the simpler nations are still the sports of the more artificial. It is not necessary that a man should earn his living by the sweat of his brow, unless he sweats easier than I do.”
—Henry David Thoreau (1817–1862)