Basic Facts

Planet’s size: Jupiter is the largest planet in the solar system. It has a diameter of 88,846 miles (which is 142,984 km). Jupiter’s diameter is 11 times that of the Earths. Its mass is equal to 2.5 times the combined mass of all the other planets in the solar system.
Atmosphere: Jupiter’s atmosphere is very like the Suns’. For instance, it is made up of mostly Hydrogen and Helium. Further into Jupiter’s atmosphere, the hydrogen gas is turned into a liquid due to increased temperature and pressure. Then, further in, the hydrogen changes into a metallic substance and is able to conduct electricity.
Water exists deep within Jupiter’s atmosphere. Jupiter has a very strong magnetic field due to its quick rotation. Jupiter possesses a magnetic field 20,000 times stronger than the Earth’s. Many of the moons circling the planet Jupiter may in fact be asteroids caught inside the planet’s strong magnetic field. Jupiter also has a huge gravitational force about 2.5 times that of Earth's. 
File:Jupiter by Cassini-Huygens.jpg
Jupiter and its belts and zones
Surface features: Jupiter has many light and dark coloured stripes, or bands. The dark bands are called belts and the light bands, light zones. Storms have raged around these belts and zones for hundreds of years.
Internal Structure of Jupiter: Jupiter’s core is thought to be made of a solid ice-rock about the size of Earth. Around this there is predicted to be a layer of liquid metallic hydrogen. The outer layer of Jupiter is made up of mainly hydrogen.


The internal structure of Jupiter
Temperature: An average temperature of -148 ºC
Weather conditions: There are strong East-west winds in a zone, and west to east winds in a belt. Wind speeds are around 360km/h in zones. Jupiter has many storm clouds, which are mainly made up of ammonia. Jupiter often experiences lightning storms due to its extremely strong magnetic field, which traps a collection of charged particles, ions, electrons and radiation.
Lightning is also present on Jupiter; sometimes reflects off the storm clouds, making Jupiter becomes clearly visible at times. There are two layers of storm clouds around Jupiter: a thick layer and a thin layer.

790106-0203 Voyager 58M to 31M reduced 
A time-lapse sequence from Voyager 1 as it approaches Jupiter.
Terraforming Jupiter:
Jupiter is a gas giant, and is made of hydrogen. Large pressure and high temperatures can cause this hydrogen to become a liquid metal, which has then been solidified into its metal form using large pressure and at a temperature of 14 kelvin (-259.15 ºC) so that humans can stand on it.

Since Jupiter’s normal magnetoscope (magnetic field around Jupiter) has a level of radiation that is 1,000 times the deadly level for a human, the radiation level has also had to be severally altered in order to allow humans to travel there.


Don't worry though, everything is safe and has been tested many times.