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:
“Families suffered badly under industrialization, but they survived, and the lives of men, women, and children improved. Children, once marginal and exploited figures, have moved to a position of greater protection and respect,... The historic decline in the overall death rates for children is an astonishing social fact, notwithstanding the disgraceful infant mortality figures for the poor and minorities. Like the decline in death from childbirth for women, this is a stunning achievement.”
—Joseph Featherstone (20th century)
“Silence is as full of potential wisdom and wit as the unhewn marble of great sculpture. The silent bear no witness against themselves.”
—Aldous Huxley (1894–1963)
“Corporate America will likely be motivated to support child care when it can be shown to have positive effects on that which management is concerned about—recruitment, retention and productivity. Indeed, employers relate to child care as a way to provide growth fostering environments for young managers.”
—Dana E. Friedman (20th century)
“I made up my mind long ago that life was too short to do anything for myself that I could pay others to do for me.”
—W. Somerset Maugham (1874–1966)
“O, mickle is the powerful grace that lies
In plants, herbs, stones, and their true qualities;
For nought so vile that on the earth doth live
But to the earth some special good doth give.”
—William Shakespeare (1564–1616)