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The Largest Planet

Jupiter is the fifth planet from the sun and the largest in our solar system. It is a gas giant with mass slightly less than one-thousandth that of the Sun but is two and a half times more massive than all of the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn, Uranus and Neptune. Together, these four planets are sometimes referred to as the Jovian planets.

When viewed from Earth, Jupiter will appear to be the third brightest object in the night sky next to the Moon and Venus. Jupiter is mainly composed of hydrogen with a quarter of its mass being helium.


Like our planet Earth, Jupiter has a bulge at its equator and this is due to its rapid rotation. The outer atmosphere is visibly segregated into several bands at different latitudes, resulting in turbulence and storms along their interacting boundaries. The most dominant feature on Jupiter is its giant red spot.

This giant red spot is actually a raging storm that is believed to have existed since the 17th century when it was first noticed through a telescope. Surrounding the plant is a powerful magnetosphere and at least 63 moons. These moons include the four largest discovered by Galileo 1610. (Io, Europa, Ganymede and callisto) Jupiter has been explored on several occasions by robotic spacecraft, most notably during the early Pioneer and Voyager flyby missions and later by the Galileo orbiter. The most recent probe to visit Jupiter was the Pluto-bound New Horizons spacecraft in late February 2007. The probe used the gravity from Jupiter to increase its speed and adjust its trajectory toward Pluto, thereby saving years of travel. Future targets for exploration in the Jovian system include the possible ice-covered liquid ocean on the moon Europa.


Jupiter's Orbit

Like the other planets in the Solar System, Jupiter follows an elliptical orbit around the Sun. At perihelion, the time when closest to the sun, Jupiter gets as close as 741 million km, or 4.95 astronomical units. It's most distant point in an orbit is known as aphelion, and when Jupiter is at aphelion, it's 817 million km, or 5.46 AU from the Sun. Jupiter takes 11.86 Earth years, or 4331 Earth days, to complete one orbit around the Sun.

Jupiter's Atmosphere

When we look at Jupiter, whether it be through a telescope or from spacecraft images, we are not shown the surface of the planet, but the atmosphere. The atmosphere appears as alternating bands of light regions, called zones, and dark regions called belts, that run parallel to the equator. The zones are higher in altitude than the belts, and are correspondingly lower in temperature. It is believed that the belts represent descending areas of low pressure. Jupiter radiates heat energy out to space by way of convection. The zones carry energy to the surface and then cool, and sink again. Jupiter's composition is nearly an exact copy of the Sun. There is about 82 % hydrogen, 18 % helium and traces of nearly all other elements. Most of this is in the form of molecular compounds, ammonia, methane, molecular hydrogen and water. The upper areas of the zones are believed to be ammonia ice crystals. Liquid ammonia probably floats below that.


Facts about Jupiter

  • Jupiter is the largest planet in our solar system and the fifth from the sun

  • Al the other planets in the solar system can fit inside jupiter

  • It takes nearly 12 Earth years for Jupiter to orbit the sun

  • Jupiter has no surface, it is a gas giant

  • Jupiter acts as a giant vacuum and if it was not in our solar system, all the other planets would be bombarded with cosmic objects

  • The mass of Jupiter is 318 times the mass of Earth

  • Jupiter's moon, Ganymede, is the largest moon in the solar system

  • Jupiter is used to catapult space probes deeper into the solar system

  • Jupiter's giant red spot is actually a storm that has raged for over 300 years

Left: Jupiter's giant red spot can be clearly seen it the planet's atmosphere.

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