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:
“[The] elderly and timid single gentleman in Paris ... never drove down the Champs Elysees without expecting an accident, and commonly witnessing one; or found himself in the neighborhood of an official without calculating the chances of a bomb. So long as the rates of progress held good, these bombs would double in force and number every ten years.”
—Henry Brooks Adams (1838–1918)
“Raising a daughter is an extremely political act in this culture. Mothers have been placed in a no-win situation with their daughters: if they teach their daughters simply how to get along in a world that has been shaped by men and male desires, then they betray their daughters’ potential But, if they do not, they leave their daughters adrift in a hostile world without survival strategies.”
—Elizabeth Debold (20th century)
“I am fearful that the paper system ... will ruin the state. Its demoralizing effects are already seen and spoken of everywhere ... I therefore protest against receiving any of that trash.”
—Andrew Jackson (1767–1845)
“If, then, we would indeed restore mankind ... let us first be as simple and well as Nature ourselves, dispel the clouds which hang over our own brows, and take up a little life into our pores. Do not stay to be an overseer of the poor, but endeavor to become one of the worthies of the world.”
—Henry David Thoreau (1817–1862)
“The Family is the Country of the heart. There is an angel in the Family who, by the mysterious influence of grace, of sweetness, and of love, renders the fulfilment of duties less wearisome, sorrows less bitter. The only pure joys unmixed with sadness which it is given to man to taste upon earth are, thanks to this angel, the joys of the Family.”
—Giuseppe Mazzini (1805–1872)