Jupiter

Jupiter, in all its Glory!

**Jupiter** is the 5th planet from the Sun, and is also the largest planet. It is so big that many Earths can fit inside of it!

Jupiter's atmospheric composition is made of the same elements as the Sun, hydrogen and helium. However, unlike the Sun, Jupiter does not have enough gravity to begin nuclear fusion and become a star. But Jupiter is at the very edge of becoming a Brown Dwarf Star, as it is denser than the largest exoplanet in the Milky Way.

Seasons on Jupiter are not very extreme because of his tilt. It takes nearly 12 years to complete his orbit, but here the interesting is that Jupiter is the fastest rotational planet in the solar system because it takes only 10 hours to complete one rotation, but Dwarf Planet Haumea is Faster.

Like all the other Jovian planets, Jupiter has a ring system. However, its ring system is the least massive out of all the planets and is much smaller than Saturn's extensive ring system and is barely visible at all.

## Atmosphere

The Atmosphere of Jupiter is made of Hydrogen, Helium, Ammonia, and few other Gases.

## Impact by Shoemaker-Levy 9

**D/1993 F2**, or **Comet Shoemaker-Levy 9**, ***was*** a short-period comet that became a moon of Jupiter around the early 1980's, after being captured. On July 16, 1994, the first comet impacted on 8:13 pm. Before this, the comet split into 21 pieces, and the first one to hit was designated as "Fragment A". The other ones collided at different times after the fact.

## Exploration

Jupiter has been Visited by Many Probes, some Including, Pioneer 10, 11 , Voyager 1, 2, Cassini, New Horizons, Juno, and Galileo.

### Pioneer Probes

The first spacecraft to explore Jupiter was *Pioneer 10*, which flew past the planet in December 1973, followed by *Pioneer 11* twelve months later. *Pioneer 10* obtained the first close-up images of Jupiter and its Galilean moons; the spacecraft studied the planet's atmosphere, detected its magnetic field, observed its radiation belts and determined that Jupiter is mainly fluid. *Pioneer 11* made its closest approach, within some 34,000 km of Jupiter's cloud tops, on December 4, 1974. It obtained dramatic images of the Great Red Spot, made the first observation of Jupiter's immense polar regions, and determined the mass of Jupiter's moon Callisto. The information gathered by these two spacecraft helped astronomers and engineers improve the design of future probes to cope more effectively with the environment around the giant planet.

### Voyager Probes

*Voyager 1* began photographing Jupiter in January 1979 and made its closest approach on March 5, 1979, at a distance of 349,000 km from Jupiter's center. This close approach allowed for greater image resolution, though the flyby's short duration meant that most observations of Jupiter's moons, rings, magnetic field, and radiation environment were made in the 48-hour period bracketing the approach, even though *Voyager 1* continued photographing the planet until April. It was soon followed by *Voyager 2*, which made its closest approach on July 9, 1979, 576,000 km away from the planet's cloud tops.The probe discovered Jupiter's ring, observed intricate vortices in its atmosphere, observed active volcanoes on Io, a process analogous to plate tectonics on Ganymede, and numerous craters on Callisto.

The *Voyager* missions vastly improved our understanding of the Galilean moons, and also discovered Jupiter's rings. They also took the first close-up images of the planet's atmosphere, revealing the Great Red Spot as a complex storm moving in a counter-clockwise direction. Other smaller storms and eddies were found throughout the banded clouds (see animation on the right). Two new, small satellites, Adrastea and Metis, were discovered orbiting just outside the ring, making them the first of Jupiter's moons to be identified by a spacecraft. A third new satellite, Thebe, was discovered between the orbits of Amalthea and Io.

The discovery of volcanic activity on the moon Io was the greatest unexpected finding of the mission, as it was the first time an active volcano was observed on a celestial body other than Earth. Together, the *Voyagers* recorded the eruption of nine volcanoes on Io, as well as evidence for other eruptions occurring between the Voyager encounters.

Europa displayed a large number of intersecting linear features in the low-resolution photos from *Voyager 1*. At first, scientists believed the features might be deep cracks, caused by crustal rifting or temporary processes. The high-resolution photos from *Voyager 2*, taken closer to Jupiter, left scientists puzzled as the features in these photos were almost entirely lacking in topographic relief. This led many to suggest that these cracks might be similar to ice floes on Earth, and that Europa might have a liquid water interior. Europa may be internally active due to tidal heating at a level about one-tenth that of Io, and as a result, the moon is thought to have a thin crust less than 30 kilometers (19 mi) thick of water ice, possibly floating on a 50-kilometer-deep (31 mi) ocean.

More information about other probes that visited Jupiter is available here.

## Moons

Jupiter has 95 moons, the Largest 4 are the Galilean Moons, that are Europa, Io, Callisto, and Ganymede. Jupiter has the 2nd most amount of Moons in the Solar System, just Behind Saturn.

## Impact on the rest of the Solar System

Jupiter has been called the Solar System's vacuum cleaner because of its immense gravity well and location near the inner Solar System. There are more impacts on Jupiter, such as comets, than on any other planet in the Solar System. For example, Jupiter experiences about 200 times more asteroid and comet impacts than Earth. In the past, scientists believed that Jupiter partially shielded the inner system from cometary bombardment. However, computer simulations in 2008 suggest that Jupiter does not cause a net decrease in the number of comets that pass through the inner Solar System, as its gravity perturbs their orbits inward roughly as often as it accretes or ejects them.This topic remains controversial among scientists, as some think it draws comets towards Earth from the Kuiper belt, while others believes that Jupiter protects Earth from the Oort cloud.