Photo of Jupiter from Cassini. Jupiter is the largest planet in the Solar System. It is the fifth planet from the Sun. Jupiter is classified as a gas giant, both because it is so large and due to the fact that it is made up mostly of gas. The other gas giants are Saturn, Uranus, and Neptune. Jupiter can be seen with the naked eye. It was known to the ancient Romans, who named it after their god Jupiter, he was known for causing lightning strikes on Earth. Jupiter is the third brightest object in the night sky. Only the Earth's moon and Venus are brighter. Jupiter has at least 67 moons. Of these, 55 are very small and less than five kilometres wide. The four largest moons of Jupiter are Io, Europa, Ganymede, and Callisto. They are collectively called the Galilean moons, because they were discovered by the Italian astronomer Galileo Galilei. Characteristics Structure
Jupiter, Earth size comparison Jupiter is the biggest planet in the Solar System with a diameter of 142,984 km. This is eleven times bigger than the diameter of Earth. The volume of Jupiter is 1,317 times the volume of Earth, in other words, 1,317 Earth-sized objects could fit inside it. Jupiter has a mass of about 318 Earths. Jupiter is twice as massive as all the other planets in the Solar System put together. It gives off more heat than it gets from the sun. Surrounding Jupiter is a faint planetary ring system and a powerful magnetosphere. Jupiter moving out of the inner Solar System would have allowed the formation of inner planets, including Earth. Jupiter shrinks by about 2 cm each year. When it was first formed, Jupiter was much hotter and was about twice its current diameter. Inner structure
Jupiter is thought to consist of a dense core with a mixture of elements, a surrounding layer of liquid metallic hydrogen with some helium, and an outer layer predominantly of molecular hydrogen. The core region may be surrounded by dense metallic hydrogen, which extends outward to about 78% of the radius of the planet. The core is often described as rocky, but its detailed composition is unknown, as are the properties of materials at the temperatures and pressures of those depths.
Great Red Spot
One of the biggest features in Jupiter's atmosphere is the Great Red Spot. It is a huge storm which is bigger than the entire Earth. The Great Red Spot is a 300-year old storm, it is known to have been in existence since at least 1831, and possibly since 1665. Storms can last for hours or as long as hundreds of years in the case of the Great Red Spot. The storm is large enough to be visible through Earth-based telescopes. Storms such as this are common within the turbulent atmospheres of giant planets. Jupiter also has white ovals and brown ovals, which are lesser unnamed storms. White ovals tend to consist of relatively cool clouds within the upper atmosphere. Brown ovals are warmer and located within the "normal cloud layer". Such storms can last as little as a few hours or stretch on for centuries.
Ring system
Jupiter also has a thin planetary ring system. These rings are very difficult to see, and so they were not discovered until NASA's Voyager 1 probe went to Jupiter in 1979. There are four parts to Jupiter's rings. The closest ring to Jupiter is called the Halo Ring. The next ring is called the Main Ring. It is about 6,440 km (4,002 mi) wide and only 30 km (19 mi) thick. The Main and Halo rings of Jupiter are made of small, dark particles. The third and fourth rings, called the Gossamer Rings, are transparent (see through) and are made from microscopic debris and dust. This dust probably comes from small meteors striking the surface of Jupiter's moons. The third ring is called the Amalthea Gossamer Ring. The outer ring is the Thebe Gossamer Ring, the outer edge of this ring is about 220,000 km (136,702 mi) from Jupiter.
Orbit
The orbit of a planet is the time and path it takes to go around the Sun. In the amount of time it takes for Jupiter to orbit the Sun once, the Earth orbits the Sun 11.86 times. One year on Jupiter is equal to 11.86 years on Earth. The average distance between Jupiter and the Sun is 778 million kilometres. This is five times the distance between Earth and the Sun. Jupiter is not tilted on its axis as much as the Earth or Mars. This causes it to have no seasons, for example summer or winter. Jupiter rotates, or spins around very quickly. This causes the planet to bulge in the middle. Jupiter is the fastest spinning planet in the Solar System. It completes one rotation or spin in 10 hours.
Gravity
Jupiter's large gravity has had a big effect on the Solar System. Jupiter protects the inner planets (including Earth) from comets and asteroids by pulling them towards itself. Jupiter has been called the Solar System's vacuum cleaner, because of its immense gravity and location near the inner Solar System. It receives the most frequent comet impacts of the Solar System's planets. Jupiter experiences about 200 times more asteroid and comet impacts than Earth.
Observation
Jupiter is the third brightest object in the night sky, after the Moon and Venus. Because of that, people have always been able to see it from Earth. The first person known to really study the planet was Galileo Galilei in 1610. He was the first person to see Jupiter's moons Io, Europa, Ganymede and Callisto. This was because he used a telescope, unlike anyone before him. No new moons were discovered for more than two hundred years. In 1892, astronomer E.E Barnard found a new moon using his observatory in California. He called the moon Amalthea. It was the last of Jupiter's 67 moons to be discovered by human observation through a telescope. Now, a small telescope will usually show Jupiter's four Galilean moons and the prominent cloud belts across Jupiter's atmosphere. A large telescope will show Jupiter's Great Red Spot when it faces Earth. In 1994, bits of the comet Shoemaker Levy-9 hit Jupiter. It was the first time a collision or crash between two Solar System objects had been directly seen by people. Moons
Io Jupiter has 67 known moons. The four largest were seen by Galileo with his primitive telescope, and nine more can be seen from Earth with modern telescopes. The rest of the moons have been identified by spacecraft. The smallest moon (S/2003 J 12) is only one kilometre across. The largest, Ganymede, has a diameter of 5,262 kilometres. It is bigger than the planet Mercury and is the largest moon in the solar system. The other three Galilean moons are Io, Europa and Callisto. Because of the way they orbit Jupiter, gravity affects three of these moons greatly. The friction caused by the gravity of Europa and Ganymede pulling on Io makes it the most volcanic object in the Solar System. It has over 400 volcanoes, more than three times as many as Earth. Jupiter's moon Europa is thought to have a giant ocean below its surface.
Questions:
1) What items in the night sky are brighter than Jupiter? 2) How many moons does Jupiter have? 3) Which is the largest moon? 4) What is Jupiter’s dense core made of? 5) Who or what is Jupiter named after? 6) Jupiter weighs how many times the mass of Earth? 7) How many Earth years is equivalent to one Jupiter year? 8) What are the names of the rings of Jupiter? 9) Who was the first person to study Jupiter? 10) What important role has Jupiter played in the history of the solar system?