It’s a bird, it’s a plane, it’s a…. meteor?!? I like to call meteors “Nature’s fireworks”. With the Fourth of July this weekend,
instead of writing about mini-rockets explode in the sky, I’d thought I’d write
about…. well, rocks exploding in the sky!
There are a lot of phenomena that can be considered Nature’s
fireworks… lightning, the aurora, volcanic eruptions… but none can really compare
to a meteor shower.
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| Four-hour time lapse image of the Leonid meteor shower in 1998. Image credit: Juraj Tóth [CC BY-SA 3.0] |
Meteor Showers
A meteor shower occurs when cosmic debris enters Earth’s
atmosphere and burns up. Most of the
time the pieces are small, about the size of a sand grain, so they will
completely burn up and never reach the Earth’s surface.
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Astronaut Ron Garan, Expedition 28 flight engineer, tweeted this image from the International Space Station in August, 2011 with the following caption: “What a `Shooting Star’ looks like from space, taken yesterday during Perseid Meteor Shower.” Image credit NASA
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Meteor showers have a periodicity and are predictable at
certain times of the year. These events
are related to comets passing close to the Earth and shedding debris. Think about Halley’s Comet coming around every 75
years. It was last here in 1986 and will
return again in 2061. The comet has
passed by Earth many times and left debris along some of its previous
paths. There are two meteor showers
associated with the debris trails: the Eta Aquariids occurring in April and May,
originating near the constellation Aquarius, and the Orionids, originating from
the constellation Orion in October. You
can check out StarDate.Org for the 2015 schedule of meteor showers. The next one is coming up in August!
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| Halley’s Comet March 8, 1986. Image credit: NASA |
Meteorites
Sometimes, cosmic debris is big enough to not burn up upon
atmospheric entry and will hit the Earth’s surface. Now we call them meteorites.
Meteorites are pretty cool because they can tell you a lot
about the origin of the larger extraterrestrial body they came from. For example, a stony meteorite comes from the rocky
crust of a small planet (planetoid) while an iron meteorite comes from the core
of a planetoid.
Now, Texas is a great place to see meteorites and their
craters. Most notable, is the Odessa
Crater. Odessa is interesting because it
is young enough for the crater to still be seen (only 25,000 years old!) and
has plenty of iron meteorite fragments. It is
also has a nice little museum/gift shop and is free and open to the
public. If you are ever out in west
Texas along Highway 20, stop in and check it out!
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| Odessa meteorite fragments. Left: A big one at 70 pounds from the museum gift shop at the crater. Image credit: Kelly Teague [CC BY-SA 2.0] Right: A much smaller fragment (quarter for scale) and recent gift from TMN... Thanks! :) |
Fireballs
Finally, cosmic debris can sometime enter Earth’s atmosphere
but just skims the surface and returns to space. These events are called fireballs. As recently as last year, a large fireball was seen in central Texas.
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| Fireball streaking across the sky similar to one seen in Texas. Image credit: Wikipedia, Public Domain |
Since we probably don’t want to wait until August for a
meteor shower or the random fireball that streaks across the sky to satisfy our
love of nature’s fireworks, it’s probably easier to go out to the local firework
display and enjoy the show!
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| Independence Day Fireworks from San Diego. Image credit: Wikipedia, Public Domain |
This weekend, be safe and enjoy the (man-made) fireworks!
References:
2015 Meteor Shower Schedule:
http://stardate.org/nightsky/meteors
Central Texas Fireball News Article: http://www.amsmeteors.org/2014/11/major-fireball-over-san-antonio-texas/
Great Non-Technical Book About Meteorites: Rocks
From Space by O. Richard Norton
