Jupiter: It and Its Mini-Solar System
If you were to observe Jupiter and it moons, you would notice that it appears to be very similar to that of which our solar system must have looked like when it had recently been created. Right now, many scientists are studying Jupiter and its moons to possibly get a closer look at how our solar system grew up into what it is today.
Jupiter is a big planet. That's how it got its name, Jupiter. Jupiter was the Roman king of the gods (He was Rome's Zeus). All big and powerful, just like the planet that was given his name. Jupiter is also very similar to what the sun was when it was just created or in the process of being created. The two major similarities are: they both have many satellites (i.e.: moons or planets), and they have the same basic chemical make-up (mostly hydrogen, some helium).
Jupiter [as you probably already know by now] is a huge planet. It is so huge that all of the other planets combined mass isn't even half of Jupiter's! It is so big that, easily, more than a thousand Earth's could fit inside this giant among planets. Its core is probably about 10-15 Earth masses in size (this isn't for sure, not much is known about the interior of Jupiter).
Jupiter has sixteen moons; some bigger than most of the inner planets. Its four biggest moons (in order off smallest of the four to largest) are Europa, Io, Callisto, and Gannymede. These were all discovered Galileo Galilei; the great italian astronomer.
Saturn: Rings Around The Floatable Planet
Do you think that an item the size of the planet Saturn could float in water? Guess what? The answer to that question is Yes; the planet Saturn could easily float in water [our only problem is that there isn't a body of water big enough to do that]. Saturn doesn't actually weigh less than water, it's just a lot less dense than water (about 30 percent).
Saturn is famous for its rings. They are beautiful and a unique part of Saturn. There are at least six different rings and they are split into many parts and made of many different types of material that is found in space, what exactly is uncertain.
From space probes sent to Saturn, we have learned that the rings of Saturn are in actuality, many small ringlets. We don't know much on how the rings were formed, but it is thought that the rings were once large moons that shattered from being hit by comets and/or meteorites.
There are 18 currently identified and named moons that belong to Saturn, and more than 12 more satellites have been reported to be orbiting Saturn. Further study has shown that at least 6 of those are large enough to be considered moons; so Saturn could actually have more than two dozen moons.
Uranus: It's Just Rolling Along
Uranus stands out from all the other planets by the fact that it seemingly rolls when it rotates around its axis. Scientists believe that it rotates like this because it might have been hit by a planet-size object that just knocked its rotation out early in the solar system's history.
Uranus is the first planet (by order) that you are unable to see without a telescope. Uranus was discovered (as a planet) by William Herschel in 1781. (It actually wasn't verified as a planet until six years later in 1787.) Herschel was doing his routine runs with his telescope when he noticed the planet. He would name it the Georgian Planet, after his patron, King George III. Most other people had called it "Herschel". The name, "Uranus" wasn't accepted into common use until 1850.
The planet had actually been seen in past years, but ignored because they just thought it was just another star [it was right under their noses the whole time]. The earliest found reporting of it was in 1690 by John Falmsteed saw and named it 34 Tauri.
Neptune: The Last of the Big Guys
Neptune is the last of the gas giants, and is the smallest in diameter of the four (it has a larger mass than Uranus). An outstanding feature of Neptune from the other planets is its blue color. The blue color is due to a fairly common gas in the upper clouds of Neptune called methane [Sound familiar. That's the gas that really smells {Pee-eww}.]
Neptune was discovered by Johann Gottried Galle and Louis d'Arrest simultaneously in 1846. It was previously noticed by Galileo in 1610 when he was observing Jupiter and Neptune's orbit was close to Jupiter's, but he just ignored it thinking it was just another star. Galileo had noticed that it had moved a little from comparisons of other stars. Some say that if were able to watch it a few nights earlier that Neptune would have been the seventh planet discovered instead of Uranus.
Pluto: The Moon Planet
Pluto is the last of the nine planets. Not much is known about Pluto because it remains to be the one and only planet to not be visited by one of Earth's spacecraft. Pluto has a single moon, named Charon (Share-on). Charon is about half the size of Pluto (Pluto's diameter is 2,274 km [1,412 mi] and Charon's diameter is 1,172 km [728 mi]).
Pluto is, by far, the smallest planet in the solar system. Pluto is smaller than seven moons in the solar system (Earth's moon, Io, Europa, Callisto and Gannymede of Jupiter, Titan of Saturn, and Triton of Neptune). Pluto was discovered on February 18, 1930 by [the only American to discovery a planet] Clyde W. Tombaugh; 84 years after Neptune had been discovered. Tombaugh was hired to be in one of three searches for the illusive "Planet X" that had to be out in space because of how it was affecting the orbits of Neptune and Uranus. The calculations that made this judgment ended up being incorrect, meaning that Pluto was discovered almost accidentally. If the calculations had been correct, meaning that nobody would have even thought about trying to discover a ninth planet, meaning there would be no Pluto [and I wouldn't have had to take so much time typing this].
