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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 and jetsam 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."
Meteor 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 automatically 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.