The Solar System is a vast collection of objects that revolve around the Sun. It formed approximately 4.6 billion years ago from a giant cloud of gas and dust called a solar nebula. The Sun is a star and contains more than 99% of the Solar System's total mass. Its gravity holds planets, moons, asteroids, comets, and other objects in orbit. The eight planets are divided into two groups. The inner planets—Mercury, Venus, Earth, and Mars—are rocky worlds with solid surfaces. The outer planets—Jupiter, Saturn, Uranus, and Neptune—are much larger. Jupiter and Saturn are gas giants, while Uranus and Neptune are often called ice giants because they contain large amounts of icy materials such as water, ammonia, and methane. Earth is unique because it has conditions suitable for life, including liquid water and a protective atmosphere. Venus is the hottest planet due to its dense atmosphere, while Mercury experiences extreme temperature changes because it has very little atmosphere. Mars is known for its reddish appearance, caused by iron-rich dust on its surface. Many planets have natural satellites called moons. Jupiter has the largest number of known moons among the planets. Saturn is famous for its extensive ring system, which is made mostly of ice particles and rocky debris. Beyond Neptune lies the Kuiper Belt, a region containing many icy bodies and dwarf planets such as Pluto. Comets travel around the Sun in elongated orbits. When a comet approaches the Sun, its ice begins to vaporize, creating a glowing coma and tail. Asteroids are smaller rocky bodies, most of which are found in the asteroid belt between Mars and Jupiter. Scientists explore the Solar System using telescopes, robotic spacecraft, satellites, and planetary landers. These missions provide valuable information about planetary environments, the origins of the Solar System, and the possibility of life beyond Earth.