Spring is Fireball Season
Presented by Science at NASA
What are the signs of spring? They are as familiar as a blooming Daffodil, a
songbird at dawn, a surprising shaft of warmth from the afternoon sun.
And, oh yes, don't forget the meteors.
"Spring is fireball season," says Bill Cooke of NASA's Meteoroid Environment
Office. "For reasons we don't fully understand, the rate of bright meteors
climbs during the weeks around the vernal equinox."
In other seasons, a person willing to watch the sky from dusk to dawn could
expect to see around 10 random or "sporadic" fireballs. A fireball is a meteor
brighter than the planet Venus. Earth is bombarded by them as our planet plows
through the flotsam jetsam and of space. For example, fragments of broken
asteroids and decaying comets that litter the inner solar system.
In spring, fireballs are more abundant. Their nightly rate mysteriously climbs
10% to 30%.
"We've known about this phenomenon for more than 30 years," says Cooke. "It's
not only fireballs that are affected. Meteorite falls, space rocks that actually
hit the ground, are more common in spring as well."
Meteoroid expert Peter Brown of the University of Western Ontario notes that
"some researchers think there might be an intrinsic variation in the meteoroid
population along Earth's orbit, with a peak in big fireball-producing debris
around spring and early summer. We probably won't know the answer until we learn
more about their orbits."
To solve this and other puzzles, Cooke is setting up a network of smart meteor
cameras around the country to photograph fireballs and triangulate their orbits.
Networked observations of spring fireballs could ultimately reveal their origin.
"It might take a few years to collect enough data," he cautions.
Until then, it's a beautiful mystery. Go out and enjoy the night sky. It is
spring, after all.
For more information about fireballs and other mysteries, please visit
science.nasa.gov.
Документальный фильм "Fireballs"
