Edna DeVore, Director of Education and Public Outreach, SETI Institute
Thursday, August 10, 2006
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.
