Like the sun, Jupiter is composed predominantly of hydrogen & helium. But unlike the sun, it lacks the necessary amount to begin fusion, the process that fuels a star. Jupiter would need to be 75-80 times more massive than it is at present to be considered a star. If all of the planets in the solar system had formed as part of the gas giant, it still would not have sufficient mass. Still, by itself, Jupiter is 2 & 1/2 times larger than all of the other planets in the solar system combined.
In Jupiter’s North Equatorial Belt, scientists spotted a rare wave that had been seen there only once before. It is similar to a wave that sometimes occurs in Earth’s atmosphere when cyclones are forming. This false-color close-up of Jupiter shows cyclones (arrows) and the wave (vertical lines). Credits: NASA/ESA/Goddard/UCBerkeley/JPL-Caltech/STScI http://www.nasa.gov/press-release/goddard/hubble-s-planetary-portrait-captures-new-changes-in-jupiter-s-great-red-spot