How Big Does a Meteoroid Have to Be to Make It to the Ground?

Meteors can put on a spectacular show, but many of the pieces of debris that cause them are the size of pebbles -- or dust. Learn more about meteorites in this episode of BrainStuff.

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Episode Transcript

Speaker 1 (00:01):
Welcome to brain Stuff, a production of iHeartRadio, Hey brain
Stuff Lauren Vogal bomb here. Meteor showers are spectacular, but
one of the most amazing things about these displays is
that the majority of the space debris that causes visible
meteors is tiny, between the size of a grain of
sand and the size of a small pebble. Discussing meteor

(00:24):
activity can be tricky because the terminology is a little confusing.
The term meteor actually refers to the streak of light
caused by a piece of space debreed burning up in
the atmosphere. The pieces of debris are called meteoroids, and
the remnants of the debris that reach Earth's surface or
the surface of other planets are called meteorites. Meteoroids come

(00:44):
in a pretty wide range of sizes. They include any
space to breed bigger than a molecule and smaller than
a hundred meters in diameter that's about three ft. A
space debreed bigger than this is considered an asteroid. But
most of the debris that Earth comes in contact with
is dust shed by comets traveling through the Solar System.
This dust tends to be made up of very small particles,

(01:08):
so how can we see a meteor caused by such
a tiny bit of matter? What these meteoroids black and mass?
They make up foreign speed, and this is what causes
the flash of light in the sky. Meteoroids enter the
atmosphere extremely high speeds a seven to forty five miles
per second, that's about eleven to seventy two kilometers per second.
They can travel at this rate very easily in the

(01:30):
near vacuum of space because there's not a lot to
stop them. Art's atmosphere, on the other hand, is full
of matter, which creates a great deal of friction on
a traveling object. This friction generates high heat up to
three thousand degrees fahrenheit or one thousand, six hundred degrees celsius,
and can raise the meteoroids surface to its boiling point
so that the meteoroid is vaporized layer by layer. The

(01:55):
friction breaks the molecules of both the meteoroid material and
the atmosphere into lowing ionized particles, which then recombine, releasing
light energy to form a bright tail. A meteor tail
caused by a grain sized meteoroid will only be a
few feet wide or about a meter, but because of
the high speed of the debris maybe many miles long.

(02:17):
So how big does a meteoroid have to be to
make it to the surface of the Earth. Perhaps surprisingly,
most of the meteoroids that reach the ground are especially small,
from microscopic to dust particle sized pieces. They don't get
vaporized because they're light enough that they slow down pretty easily.
I'm moving in a mirror one inch or two and
a half centimeters per second through the atmosphere. They don't

(02:40):
experience the intense friction that larger meteoroids do. In this sense,
most all meteoroids that enter the atmosphere make it to
the ground in the form of microscopic dust, as four
meteoroids that are big enough to form visible meteors. Estimates
for the minimum size vary. This is because there are
factors other than size involved. Most notably, a meteoroid's entry

(03:04):
speed affects its chances of reaching the surface because it
determines the amount of friction the meteoroid experiences. And typically,
though a meteoroid would have to be about the size
of a marble for a portion of it to reach
the Earth's surface, smaller particles burn up in the atmosphere.
The meteorites a person is likely to find on the
ground probably come from significantly larger meteoroids, pieces of debris

(03:27):
at least the size of basketball, typically because larger meteoroids
usually break up into smaller chunks as they travel through
the atmosphere. Estimates of how much space debris false to
Earth very widely. Researchers have looked at everything from polar
ice cores to the composition of the atmosphere to try
to ssess it out. Studies from the past few years

(03:47):
have indicated that as much as sixty tons of space
dust and tiny rocks might make impact every day, which
means that chances are decent that you can find some
in your own backyard. You can try putting out a
pan on a clear or day or night, or looking
for tiny rocks near the outlet of rain gutter pipes.
A strong magnet will pick up potential micro meteorites. Of course,

(04:09):
some normal earth stuff will latch onto a magnet too.
You can tell micro meteorites apart because they'll be spherical,
and if you look at them under a microscope, they'll
have a glassy crusting formed during their fiery fall. Today's
episode was written by somebody on the house Stuff Works
team in the Way Back and produced by Tyler Clang.

(04:31):
For more in this and lots of other topics, visit
how stuff works dot com. Rain Stuff is production of
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