SOLAR SYSTEM

Our solar system consists of:
One central star — the Sun and the Eight planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune, More than 140 moons Millions of rocky asteroids Billions of icy comets
Our solar system has eight planets and one star: the Sun. The planets are (in order, from the Sun, outward): Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Pluto was considered the ninth planet until August 2006, when the International Astronomical Union reclassified it as a "dwarf planet." A new mnemonic used to remember the planets in order is, "My Very Educated Mother Just Served Us Nachos."
The planets, asteroids, and comets in the solar system are loose particles left over from the formation of the Sun. Originally the gas and dust that would become the Sun was the core of a cloud much larger than the solar system, probably several light-years across One light-year is approximately 10 trillion (10,000,000,000,000) km, or 6 trillion miles. The core was slowly rotating at first, but as the cloud collapsed it spun faster, like a spinning ice skater pulling in his arms. The rotation prevented the material at the core's equator from collapsing as fast as the material at the poles, so the core became a spinning disk.
Gas and dust in the disk spiraled gradually in to the center, where it accumulated to form the Sun. But because dust is denser than gas, some of the dust settled to the mid-plane of the disk. These dust particles stuck together to make clumps, then clumps stuck together to make rocks, then rocks collided to make planets. In the case of the "gas giant" planets (Jupiter, Saturn, Uranus, and Neptune), the rocky cores were massive enough to also attract appreciable amounts of gas. The outer layers of Jupiter and Saturn are made up of hydrogen and other gases. Uranus and Neptune are also gas giant planets, but they were built up mainly from ice chunks.
The Sun, then, is the collapsed core of an interstellar gas cloud. The planets, asteroids, and comets are small lumps of dust or ice chunks that stayed in orbit instead of spiraling into the Sun. The planets all formed within a very short period — probably a few million years — about 5 billion years ago.