The
Perseid meteor shower peaks this weekend. The best night to go out is Saturday
night, August 12/13. The first hour of the night will be dark and a small
number of Perseids will streak long tracks when they fall into Earth's
atmosphere at a grazing angle. Later in the night, the Moon will light up the
sky; it's just a few days past full Moon this weekend. The Perseid rate will
increase because the meteors fall in at a steeper angle; the meteors are short
and swift then. While moonlight (and street lights) will wash out faint
meteors, you will still have the opportunity in clear weather to see the many
bright meteors from this classic, late-summer meteor shower.
Meteor
showers occur as the Earth collides with the debris (called "meteoroids") shed
by a comet. Annually, we collide with several different debris streams that
originate from different parent bodies, all comets of one sort or another.
These occur at predictable times of the year. Infrequently, the Earth plows
into a fresh stream of debris and people see a meteor storm for a few hours
with tens to hundreds of meteors per minute. As Chicken Little was prone to
predicting, when a meteor storm occurs, it looks the sky is falling.
As
a girl, I once saw a small storm of meteors (called an "outburst") while
camping in California's Sierra Nevada Mountains. There were more meteors
than I could count, and they fell across the sky for about 2 hours that late
night. This outburst was not officially reported and it remains unknown what
dangerous comet was the cause. If freshly ejected meteoroids can hit the Earth,
so can in principle the comet. It's one of my life experiences that drew me to
astronomy. I've not seen such a storm since, but can recall the beauty of the
event easily.
There
are some that do everything in their means to try to see such outbursts. At the
SETI Institute, Dr. Peter Jenniskens studies meteor showers. Over the past
several years, he's led several airborne research campaigns to travel to the
right place on Earth and study these ephemeral bits of glowing debris as they
plunge into our atmosphere. Jenniskens studies meteors in order to better
understand comets and their contribution to the origin of life on Earth, as
meteoroids are samples of the material that rained down on the Earth the carbon
needed for life. For more than twenty years, he's pursued these short-lived
objects to better understand how to predict meteor storms and to use those
storms to study how the meteors deposit their carbon content into our
atmosphere.
Studying
meteors started as a hobby. Fresh from a small-town upbringing in the Netherlands, Jenniskens found his
first year of astronomy and city life at Leiden University difficult. He enjoyed his extracurricular
pursuits and explains that "after classes in Algebra and Classical Mechanics"
he "learned to be a scientist among amateur astronomers." Joining the newly
founded Dutch Meteor Society, Jenniskens would be an active member for the next
twenty years, helping the group "revive the sleepy field of meteor shower
research."
In
1995 Jenniskens arrived at the SETI Institute as America's only astronomer with a Ph.D. thesis on
telescopic observations of organic molecules in interstellar space, a NASA Ames
post doctorate position to study the ice of comets in the laboratory, and
scientific papers about meteor showers. "Meteor showers provide a great chance
to study the unique ways in which those extraterrestrial organic molecules were
chemically changed during delivery to Earth billions of years ago, when life
first started here," he explains.
"I'm
drawn to obscure fields in science hoping to make an impact," says Jenniskens,
who also works hard to interest others in those fields. "Science is twice the
fun when shared and appreciated by others," he says. "The most exciting moments
are when we search to define new experiments and observing techniques. There is
the fantastic feeling of opportunity, of doors unopened."
One
of the best ways to share science is to publish. On September 9, Cambridge
University Press is releasing a new book, "Meteor Showers and their Parent
Comets" authored by Peter Jenniskens. It is a great introduction in the field
of minor planets, using meteor showers as something everybody can relate to. It
also narrates recent progress in how to predict meteor outbursts and the
discovery of (mostly) dormant comets as parents of meteor showers; Jenniskens
himself identified the parent of the Quadrantid shower. The book has an
exhaustive set of tables describing major and minor meteor showers, predictions
of future meteor outbursts in the next fifty years, and the scientific results
of many people working together on predicting meteor storms and observing and
analyzing meteors on Jenniskens' airborne campaigns with NASA. Jenniskens'
handbook will be of interest to professional and amateur astronomers alike.
We
checked to see if my childhood's meteor shower was listed, but it appears to
have happened unnoticed by professionals in the field. Many such unusual
showers are predicted to return in the next fifty years, and I look forward to
consulting Peter's meteor shower predictions to plan my future camping trips.
Perhaps I'll have the delightful opportunity to see a meteor storm again, and
imagine that the sky is falling.
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