Jupiter the planet is fifth from the Sun and the largest planet in our solar system. This planet is so massive it's two and a half times the mass of all the other planets in our Solar System combined.
A "Jupiter mass" (MJ or MJup) is often used as a unit to describe masses of other objects, particularly extrasolar planets and brown dwarfs.
The first of the "outer" planets or gas giants, is also the fastest spinning of all the planets. The day is less than ten Earth hours long.
The year is almost 12 Earth years long...though that's less than half the time it takes Saturn to orbit the Sun.
This massive giant rotates so fast that, like Saturn, it creates an equatorial bulge easily seen through an Earth-based amateur telescope.
Earth overtakes it in orbit every 398.9 days as it orbits the Sun, a duration called the synodic period. As it does so, the Jovian giant appears to undergo retrograde motion with respect to the background stars. That means for a period it seems to move backward in the night sky, performing a looping motion.
Viewing the planet can be quite rewarding. It is visible to the naked eye in the night sky and, can occasionally be seen in the daytime when the sun is low.
When viewed from Earth, this “star” can reach an apparent magnitude of -2.94, making it on average the third-brightest object in the night sky after the Moon and Venus. Mars can briefly match this brightness at certain points in its own orbit.
Favorable oppositions occur when passing through perihelion, an event that occurs once per orbit. Perihelion is when a celestial body is nearest to the Sun. The opposite is aphelion.
Because the orbit of Jupiter is outside the Earth's, the planet always appears nearly fully illuminated when viewed through Earth-based telescopes.
Surrounding the planet is a faint planetary ring system, though nothing as majestic as Saturn's, and a powerful magnetosphere.
Jupiter is thrilling to view in just about any telescope, even a small refractor will reveal several cloud belts and its four brightest moons. Although this planet is big and bright, it doesn't tolerate high magnification well. Consequently, you will rarely use more than 40x per inch of aperture.
There are over 60 moons orbiting the planet. The four largest moons, known as the "Galilean Moons", are Io, Europa, Ganymede and Callisto. These were first discovered by Galileo Galilei in 1610. Ganymede, the largest of these moons, has a diameter greater than that of Mercury. The four Galilean moons are easily visible with binoculars; a few bands and the Great Red Spot can be seen with a small telescope.
The Great Red Spot is a gigantic storm raging in the atmosphere. The storm is so large that almost 3 Earths could fit inside it. That's one huge hurricane.
There are many other storms raging in the atmosphere. Sometimes they even crash into each other and create larger storms.
Jupiter is also one of the most dynamic telescopic sights — you never get the same view twice. This is partly the result of its rapid rotation. You simply must have it on your stargazing plan. Imagine how Galileo felt as he noticed those moons for the first time and realized what they were. Think how you will feel when you to do it for the first time. It's all there all you have to do is... just look upCelestial Solar System › PLANETS › Jupiter