Topic – They Came from Outer Space

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Read the Following Selection

Read about comets and asteroids, or click on the play button below to listen aloud.

They Came from Outer Space


You might say a comet is a dirty snowball that orbits the Sun. This snowball is about the size of a small city! As this snowball zooms closer to the Sun, its surface begins to turn into gas. Gas and dust stream out into a tail that can spread out as far as 80 000 km.

Comets mostly stay farther away from the Sun than our planets are. You will rarely see a comet unless you use a telescope or binoculars. Halley’s Comet is the most famous comet. It swings by Earth about every 75 years. You will have to wait until 2062 to see it again.


These space rocks may be shaped like balls, lumpy slabs, or bricks. You find asteroids circling the Sun in the Asteroid Belt, a band that lies between the planets Mars and Jupiter.

The biggest asteroid is bigger than many Canadian provinces. One asteroid even has its own moon. Most asteroids are only about the size of a house. You need binoculars to seem them.


Small chunks of asteroids or old comets may become meteoroids. When these rocky bits enter Earth’s atmosphere, they become meteors. Ever seen shooting stars? Then you have seen meteors. They burn up and shoot out fiery trails as they fall. If a meteor hits our planet, it gets a new name: meteorite.

Meteors are tiny. Most are as small as grains of sand and few get as big as baseballs. At certain times of year, many meteors streak through the night sky in a meteor shower. You can see them just by gazing up on a clear, dark night.

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