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Leonids are time capsules,
and maybe more
As you gaze into the early
morning sky Wednesday, consider what you’re looking for: Tiny bits of primordial
material generated in the cataclysm that was our solar system’s birth.
The Leonids are bits of
comet debris, and scientists think comets formed along with the solar system’s
generation, some 4.6 billion years ago, when the Sun condensed out of a cloud
of hydrogen, helium and some dust. Tempel-Tuttle built itself out of some leftovers
and has been looping around the Sun ever since, presumably, and its heart is
pristine. Until corrupted on each pass by solar radiation that boils some of
the comet into space.
The streaks of light you’ll
see as these meteoroids strike the atmosphere probably represent the best glimpse
you’ll ever have at the brimstone that ruled the solar system in the early days,
before the planets had swept most of the leftovers up. Back then, stuff small
and large hit Earth all the time. I say probably see because there are
grander examples of this housecleaning to come: comets like Tempel-Tuttle do
strike Earth now and then, and always will.
That’s an event you don’t
want to witness. And you probably won’t have to. No comets (or asteroids) are
known to be on collision courses with Earth right now. Odds are a big one won’t
hit for a long, long time.
Meanwhile, the ephemeral
Leonids (or any meteors) are prized targets of scientific study, and scientists
have used airplanes to examine a few at pretty close range in recent years.
What did they find? Nothing less than the seeds
of life, chemical precursors to biological activity that might long ago
have survived inside a comet during a plunge into Earth’s initially barren womb.
Yes, you may be related,
in a distant way, to the streaks of light expected to grace the early morning
sky this Nov. 19.
Editor's Note: Some
of the material in this article originally appeared prior to the 2002 Leonid
meteor shower.
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