31 March 2011: What are the signs of spring? You are as familiar as a blooming daffodil, a bird in the twilight, a surprising wave of heat from the Sun in the afternoon.
And, oh yes, forget not the meteors.
"Fireball spring season," says Bill Cooke of the meteoroid environment Center of NASA. "For reasons we don't fully understand, the rate of bright meteors is increasing in the weeks around the vernal equinox."
In other seasons, a person about 10 random or "sporadic" fireballs could ready, expect the sky from dusk to dawn. A fireball is a Meteor brighter than the planet Venus. Earth is bombarded by them, such as our planet space plows through the Jetsam and flotsam- that is, fragments of broken asteroids and comets decaying, the the inner solar system litter.
Fireballs are more abundant in spring. Its nightly rate rises to mysterious way 10% to 30%.
"We have known about this phenomenon for more than 30 years," says Cooke. "It is not only fireballs that are affected." Meteorite waiving - space rocks, which is actually on the ground-pitch are more common in the spring as well1. "
Researchers, the Earth meteoroid environment study never have a satisfactory explanation for the additional fireballs come up with can be. In fact, the more you think about it, the foreign is obtained.
Consider the following:
There is a point in the heavens called "Top of the Earth away." It is simple, is the direction that travel our planet. Like Earth, the Sun circles the apex circle, the heavens, completing a journey through the Zodiac every year.
The apex is important, as it is, where sporadic meteors were allegedly. If Earth were a car, the top would be the front windshield. When a car on a country road, accumulate insects on the glass to the front. Dito meteoroids swept from Earth.
Every year in the autumn, the apex rises to its highest point in the night sky. At this time are sporadic meteors of ordinary brightness in abundance, sometimes dozens per night.
Read the again: each year in the autumn.
"Autumn is the season for sporadic meteors," says Cooke. "So why are the sporadic meteors in the spring high?" "This is the secret."
Meteoroid expert Peter Brown of the University of Western Ontario finds that "Some researchers there could be an intrinsic variation in the meteoroid believe population along the Earth's orbit, with a tip in large dirt-producing fireball around spring and early summer." "We are not probably know the answer until we learn more about their orbits2."
To solve this and other puzzle is Cooke set up a network of smart Meteor cameras to photograph the country fireballs and trianguliert their orbits. As in the Science@NASA history explained is what hit Earth?, looking for places to put his cameras. Educators are encouraged to become involved. Networked observations spring fireballs could finally show their origin.
"It could collect a few years enough data take," he warns.
Until then, it is a beautiful mystery. Go and enjoy the night sky. It is spring, after all.
Author: Dr. Tony Phillips | Credit: Science@NASA
NASA's all-sky fireball network-check out this website last night fireballs map
Footnotes:
(1) A study on the relative prices of meteorites falls on the Erdoberfl?che--by Ian Halliday and Arthur A. Griffin, Meteoritics, vol. 17, no. 1, March 31, 1982
(2) Peter Brown notes that is highest in the spring the Antapex of Earth way. The Antapex is the opposite of the top. It is the direction which the Earth of the position is. The sporadic Meteors from the Antapex could come? "There is no evidence for an Antapex source of fireballs." "Details are data from different latitudes is still unclear, but partly due to the lack of fireball."
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