|
What is a meteorite?
Look! Up there! On many clear nights you may
be lucky enough to see a spark blazing across the sky. Small
dust particles which were originally part of a comet or
asteroid sometimes flash and fizzle overhead. We call them
shooting stars, zipping across the heavens traveling up
to 11.2 kilometers per second (7 mi/sec) to as much as 64
kilometers per second (40 mi/sec).
Meteoroids are chunks of rock in space, usually
a piece of an asteroid or comet. Most often less than 10
meters (33 feet) wide, they can be as tiny as a grain of
sand or dust. A meteor, or shooting star, is a streak of
light that is caused by the friction when a meteoroid from
space enters the Earth’s atmosphere.
Some nights, this display is almost guaranteed.
As Earth travels through a comet’s path full of debris,
up to forty annual meteor showers occur each year. Six of
those promise spectacular nightly displays. Plan your next
“shooting star party” around one of the better
viewing opportunities during January 1–4, April 19–23,
August 10–14, October 18–23, November 14–20,
or December 10–15.
Most objects from space never reach Earth’s
surface because friction from the Earth’s atmosphere
burns them up. Some larger objects survive this journey.
Meteorites are space rocks that survive the friction of
the atmosphere and land on Earth.
Meteorites come in all sizes, from small pebbles
to three-ton and larger boulders.
They’re grouped by their composition
into several classes such as irons, stony, and stony-irons.
Based upon these materials and a radioactive birth date
of about four billion years, many astronomers believe that
these chunks might be fragments left over from the formation
of our solar system.
Thousands of meteorites found in Antarctica
are studied and stored at NASA’s Johnson Space Center.
Scientists covet meteorites from Antarctica. Dark meteorites
are easy to find against the white background as the covering
melts. Researchers study them, looking for answers to questions
about the solar system, Earth’s formation, and life’s
beginning. Chunks from Mars and Earth’s moon are included
in the stash. Asteroids are thought to be the leftovers
from the formation of the inner solar system, including
Earth. Comets are thought to be leftovers from the formation
of the outer planets.
Some meteorites have left their mark on Earth.
In 1911, a meteorite hit and killed a small
dog in Egypt. A meteorite hit a woman’s arm as it
crashed through her roof as she was napping in Alabama in
1954. In 1992, another hit and damaged a car but fortunately
the owner sold it for more than it was worth.
Believed to be nearly 20,000 years old, Barringer
Crater in Arizona is a more permanent reminder of a meteorite
visit. Nearly 1.2 kilometers (0.75 miles) wide, 174 meters
(190 yards) deep, and with a rim rising 50 meters (150 feet)
above the surrounding surface, this crater was formed by
a crashing meteorite. Over 30 tons of iron fragments dot
the surrounding surface of the crater.
In 1908, Siberians witnessed one of the most spectacular
collisions recorded. A brilliant fireball pounded the Earth’s
surface, creating a shock wave strong enough to rattle windows
hundreds of miles away. During this catastrophic event,
approximately a 32 kilometer (20 mile) zone of trees was
scorched and knocked over, reportedly killing nearly 1500
reindeer.
The majority of meteorites are much less spectacular.
Billions of “micrometeorites” pebble the Earth’s
surface. Imagine what these extraterrestrial particles could
tell you about their trip to Earth.
Visit the links below for more resources from
NASA:
Comet
Coloring - To develop an understanding that
some meteoroids are naturally formed objects, which are
made of pieces of comets, in space.
Watch
Out! - To demonstrate meteorite impacts on
various surfaces, and to analyze impact data.
Look
Out for Space Debris - To simulate impacts
of space debris into various materials.
Planetary
Geology Educator's Guide - This educator's
guide features lesson plans and activities on the following
topics: introduction to geologic processes, impact cratering
activities, planetary atmospheres, planetary surfaces, and
planetary geologic mapping.
Exploring
the Moon Educator's Guide -
This teacher's guide provides detailed background information
about the moon, with lesson plans and activities divided
into three units: Pre-Apollo, Learning from Apollo, and
the Future.
Asteroid
Facts and Pictures - Brief overview and description
of asteroids, which includes some pictures that you cannot
find just anywhere. (PDF)
Space
Rocks - This feature, write to grade levels
5-8, provides an excellent description of the types of "rocks"
that can be found in space, some of which end up on Earth.
Multimedia links and realted sites are included, making
this a valued reference for any middle school student.
Rocks
in Space - A storybook for kids to explain
the many types of "rocks in space."
|
