© Shell Education #50160—Leveled Texts for Science: Earth & Space Science
The Outer Planets
There are a many planets that orbit our sun. Some planets are like our own
planet. Some are not like Earth. The planets of the outer solar system are strange.
They are not like Earth at all!
Jupiter is the largest planet. You could put all the other planets together. It would still be bigger. It is one of
four gas giants. They are planets made of gas. Jupiter has at least 63 moons. It has three rings, too. It has a huge storm in
its clouds. It is called the Great Red Spot. The storm is at least 300 years old!
Saturn is a very pretty planet. It has many rings. These rings are made of ice and rock. They are held in orbit around the planet. Their own speed pulls them out. Saturn’s gravity pulls them in. They stay where they are. Saturn is the second largest of the outer planets. It is also made of gas. It has at least 59 moons. The most famous one is Titan. It is the only moon with air we know of.
Uranus was found with a telescope. It was the first planet found this way. It looks like a blue green disk. It lies on its side. Some astronomers think a huge object may have crashed into it. It knocked Uranus on its side. Voyager2is the only space probe to fly past the planet. It helped find most of its 27 known moons. Uranus has at least 11 rings.
#50160—Leveled Texts for Science: Earth & Space Science © Shell Education
In 1846, scientists looked for one more planet. They knew Uranus moved strangely. They thought one more planet was the reason why. They made a chart of where they thought it might be. They pointed their telescopes at that point. There was Neptune!
Neptune is the last of the four giant planets. It is deep blue in color.
It was named after the Roman god of the sea. It has six rings. It has at least 13
moons. The weather on Neptune is fierce. Winds whip up to more than 1,995 kilometers
(1,250 miles) per hour!
Scientists wanted to find a ninth planet. They tried the same trick. They charted where they thought it would be. When they looked, they found Pluto. It was found in 1930. It is far from the sun. It is 5.9 billion kilometers (3.7 billion miles) away! It takes Pluto 248 of our years to orbit the sun just once.
Pluto is tiny. It is just two-thirds the size of our moon. Is it a planet? Scientists did not know if it was big enough. They now call Pluto a dwarf planet.
Comprehension QuestionHow is Pluto different from the outer planets?