Check your answers.

	1. I travel around the sun faster than any other planet. (b.) Mercury It only takes 88 days for Mercury to orbit around the sun. No other planet travels around the sun faster.
	2. My name says I am the prettiest planet. I am Earth's twin sister -- the prettier sister.  (c.) Venus The planet Venus is so bright in the night sky that you may think it is a star. The Romans thought the planet was so pretty that they named it after a goddess. In Roman mythology, Venus was the goddess of love and beauty. From far away, Venus and Earth look like twin sisters.
	3. My surface is red because it is has iron oxide (rust). That's why they call me the "Red Planet."   (a.) Mars The red dust from the ground blows into the sky. This makes the sky look pink on Mars.
	4. I am the third planet from the sun.  (b.) Earth Our solar system has nine planets. Earth is the third planet from the sun. Mercury is the first because it is closest to the sun. Venus is second.
	5. I am the star of the solar system.   (c.) sun Our sun is a star. It the closest star to Earth. It is the only star in our solar system.
	6. I am the windiest planet in the solar system.  (b.) Neptune The winds on Neptune blow at more than 2,000 kilometers per hour (1,200 miles per hour).
	7. I am so far from the sun that noon is as dark as a moonlit night.  (a.) Pluto If you were on the planet Mercury, the sun would look much brighter than it does on Earth. But if you were on far away Pluto, the sun would not look very bright.
	8. I send heat and light to Earth.  (c.) sun We need the sun. The sun gives us heat and light. If we did not have the sun, Earth would be very cold and dark. No one would be able to live on Earth.
	9. I have the brightest rings in the solar system.  (c.) Saturn Four planets have rings. Saturn's rings are the brightest. This could mean that they are the newest.
	10. I am a hot planet, but my temperature can drop 600 Celsius at night. That's because I don't have an atmosphere to trap the heat.  (b.) Mercury Mercury is the closest planet to the sun, so it is very hot. But Mercury does not have any air or atmosphere around it. It gets very cold on Mercury at night because there is no atmosphere to trap the daytime heat.
	11. I am Earth's natural satellite.  (a.) moon A satellite is an object that revolves around a planet. People have sent man-made satellites into space. But the moon is a natural satellite.
	12. It takes me 365 days to revolve around the sun.   (b.) Earth All of the planets in our solar system revolve around or orbit, the sun. It takes each planet a different amount of time to complete a trip around the sun. The farther a planet is from the sun, the longer it takes to travel around the sun. This time is called the planet's period of revolution or one year on the planet. Earth's year is 365 days.
	13. I am the only heavenly body on which humans have landed.  (a.) moon One day we hope to send people to Mars. But for now, the moon is the only place where people have landed. Neil Armstrong was the first person to set foot on the moon. He did this on July 20, 1969. Twelve people have walked on the moon.
	14. Like Jupiter, Saturn and Neptune, I am made mostly of gases.   (a.) Uranus Jupiter, Saturn, Neptune and Uranus are large planets made mostly of gases. They are called the gas giants.
	15. I am the biggest planet in the solar system. All of the other planets could fit inside of me.   (b.) Jupiter It would take more than 1,300 Earths to fill up Jupiter. This planet is so large that if the inside were empty, all of the other planets would fit inside it.

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