THE SOLAR SYSTEM
In grade school, we were taught the solar system consists of the sun, nine planets, and their moons. It’s not that simple.
No one really knows how many planets there are because there is no settled scientific definition of a planet. All astronomers agree upon the validity of the four terrestrial planets__ Mercury, Benus, Earth, and Mars__and the four gaseous giants__ Jupiter, Saturn, Uranus, and Neptune__ but arctic Pluto is a matter of great dispute.
Pluto is about two-thirds the size of our moon and takes 248 years to orbit the sun. The tiny i e planet travels in a strange elliptical orbit on a different planet than then other eight. Its coldness, distance from the other planets, and warped path around the sun has led many scientists to believe that it is really a comet in the Kuiper Belt, a region of icy debrics on the outskirts of the solar system.
Pluto has a recently discovered rival on the Kuiper Belt, a hunk of frozen rock officially referred to as 2003 UN313 but informally called Xena. The object is three times farther from the sun than Pluto and has an even stranger 560-year orbit, tilted 45 degrees off the plane of the rest of the planets. But 2003 UB313 is larger than Pluto, and many scientists feel that if Pluto deserves to be called a planet, then it does, too.
ADDITIONAL FACTS
1.Two other Large frozen objects in the Kuiper Belt__ Quaoar and Sedna___ are almost as big as Pluto. They may become the eleventh and twelfth planets.
2.Astronomer Michael E. Brown discovered 2003 UB313 and nicknamed it Xena after the TV show starring Lucy Lawless as ancient Greek warrior princess. He hopes to make Xena the official name.
3.Our solar system has 153 known moons, but that nber is highly contested.
4.Seven moons in the solar system are Large than Pluto. This includes Jupiter’s Io, which has
Puzzle 