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Solar System
 Is Pluto a Planet?

Is Pluto a Planet?
Reading Level
     edHelper's suggested reading level:   high interest, readability grades 4 to 6
     Flesch-Kincaid grade level:   4.28

Vocabulary
     challenging words:    asteroid, nitrogen, underworld, launched, billion, gravity, rate, size, dioxide, satellite, actually, travels, astronomer, rotation, powerful, pounds
     content words:    International Astronomical Union, Kuiper Belt, Clyde Tombaugh, From Pluto, New Horizons

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Is Pluto a Planet?
By Patti Hutchison 		  
1     Caption: size comparison of Earth, Earth's moon, Pluto, and its moon, Charon
 
2     It is; it isn't. It is, but with some restrictions. No, it isn't. Yes, it is, sort of. These are the arguments poor Pluto has been going through. Is it a planet, or isn't it?
 
3     Pluto was once thought of as the smallest planet. It was also known as the coldest planet since it is the farthest from the Sun. It was discovered in 1930. Since then, scientists have had trouble deciding if it really is a planet or not.
 
4     In 2006, the International Astronomical Union (IAU) made some new "planetary rules." According to the new rules, a true planet must do three things. First, it must orbit the Sun. Secondly, it must be big enough for gravity to make it into a round ball. And lastly, it must have cleared out its orbital neighborhood. There can't be any "junk" floating around it.
 
5     Let's look at these criteria in terms of Pluto. It does follow rule number one. It orbits the Sun. How about rule number two? Yes, it follows rule number two. It is a round ball.

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