WEBVTT - How big does a meteor have to be to reach the ground?

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<v Speaker 1>Welcome to brain Stuff from house Stuff works dot com,

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<v Speaker 1>where smart happens Him Marshall Brain with today's question, how

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<v Speaker 1>big does a meteor have to be to make it

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<v Speaker 1>to the ground. If you've spent much time looking up

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<v Speaker 1>at the night sky, you've probably seen some spectacular meteors

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<v Speaker 1>and meteor showers. One of the most amazing things about

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<v Speaker 1>these displays is that the majority of the space does

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<v Speaker 1>that causes visible meteors is tiny, between the size of

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<v Speaker 1>a grain of sand and the size of a small pebble.

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<v Speaker 1>Discussing meteor activity can be tricky because the terminology is

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<v Speaker 1>pretty confusing. The term meteor actually refers to the streak

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<v Speaker 1>of light caused by a piece of space debris burning

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<v Speaker 1>up in the atmosphere. The pieces of debris are called meteoroids,

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<v Speaker 1>and remnants of the debris that actually each Earth's surface

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<v Speaker 1>or another planets for that matter, are called meteorites. Meteoroids

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<v Speaker 1>have a pretty big size range. They include any space

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<v Speaker 1>debris bigger than a molecule and smaller than about three

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<v Speaker 1>thirty feet or a hundred meters in diameter. Space debris

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<v Speaker 1>bigger than this is considered an asteroid, but most of

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<v Speaker 1>the debris the Earth comes into contact with is dust

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<v Speaker 1>shed by comets traveling through the Solar System. This dust

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<v Speaker 1>tends to make up the small particles that we see

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<v Speaker 1>as meteors. So how can we see a meteor caused

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<v Speaker 1>by such a small bit of matter. It turns out

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<v Speaker 1>that what these meteoroids lack in mass, they make up

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<v Speaker 1>for in speed, and this is what causes the flash

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<v Speaker 1>of light in the sky. Meteoroids enter the atmosphere at

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<v Speaker 1>extremely high speeds seven to forty five miles per second

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<v Speaker 1>or eleven to seventy two kilometers per second. They can

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<v Speaker 1>travel at this rate very easily in the vacuum of

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<v Speaker 1>space because there's nothing to stop them. Earth's atmosphere, on

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<v Speaker 1>the other hand, is full of matter, which creates a

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<v Speaker 1>great deal of friction on the traveling object. This friction

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<v Speaker 1>generates enough heat up to three thousand degrees fahrenheit or

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<v Speaker 1>degrees celsius, to raise the meteoroid surface to its boiling point,

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<v Speaker 1>so the meteoroid is vaporized layer by layer. The friction

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<v Speaker 1>breaks the molecules of both the meteoroid material and the

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<v Speaker 1>atmosphere into glowing ionized particles, which then recombine, releasing light energy.

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<v Speaker 1>To form a bright tail. A meteor tail caused by

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<v Speaker 1>a grain sized meteoroid is a few feet wide about

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<v Speaker 1>a meter, but because of the high speed of the debris,

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<v Speaker 1>maybe many miles long. So how big does a meteoroid

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<v Speaker 1>have to be to make it to the surface of

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<v Speaker 1>the Earth. Surprisingly, most of the meteoroids that reach the

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<v Speaker 1>ground are a specially small, from microscopic debris to dust

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<v Speaker 1>size particle pieces. They don't get vaporized because they're light

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<v Speaker 1>enough that they slow down very easily, moving about one

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<v Speaker 1>inch or two and a half centimeters per second through

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<v Speaker 1>the atmosphere. They don't experience the intense friction that larger

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<v Speaker 1>meteoroids do. In this sense, most all meteoroids that enter

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<v Speaker 1>the atmosphere make it to the ground in the form

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<v Speaker 1>of microscopic dust. As for the meteoroids big enough to

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<v Speaker 1>form visible meteors, estimates for the minimum size vary. This

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<v Speaker 1>is because there are factors other than size involved. Most notably,

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<v Speaker 1>a meteoroid's entry speed affects its chances of reaching the

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<v Speaker 1>surface because it determines the amount of friction the meteoroid experiences. Typically,

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<v Speaker 1>though a meteoroid would have to be about the size

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<v Speaker 1>of a marble or a portion of it to reach

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<v Speaker 1>the Earth's surface. Smaller particles burn up in the atmosphere

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<v Speaker 1>about fifty seven five miles above the Earth. The fist

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<v Speaker 1>size meteorites a person is likely to find on the

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<v Speaker 1>ground probably came from something significantly larger pieces of debris

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<v Speaker 1>at least the size of a basketball. Since larger meteoroids

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<v Speaker 1>usually break up into smaller chunks as they travel through

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<v Speaker 1>the atmosphere, you can actually find and collect tiny meteorites

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<v Speaker 1>that have made it through the Earth's atmosphere. With this

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<v Speaker 1>simple experiment, put a pan on your back porch or

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<v Speaker 1>deck and catch them. You can find sites on the

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<v Speaker 1>web that will show you how to identify the difference

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<v Speaker 1>between meteorites and bits of sand and dust. For more

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<v Speaker 1>illness and thousands of other topics. Does that how stuff

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