The solar system includes the sun, the nearest star to us, and the planets Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto, in addition to numerous comets, asteroids, meteoroids, and the interplanetary medium. The nine planets, together with their satellites, revolve around the sun in certain orbits. The planets and the satellites are said to be the members of the solar family or the solar system.
It’s thought that the sun, the center-piece of the solar system, has been born five billion years back, emitting heat and light non-stop, and it’s expected to do so for another five billion years. The sun is the richest repository of electromagnetic energy, in the form of heat and light. The sun contains 99.85 per cent of all of the matter in the solar system. The planets, which were condensed out of the same disk of material that formed the sun, comprise just 0.135 percent of the mass of the solar system.
The four innermost planets – Mercury, Venus, Earth, and Mars – are called terrestrial planets. All of them have compact, rugged surfaces such as the Earth’s. Jupiter, Saturn, Uranus, and Neptune are known as the Jovian (Jupiter-like) planets due to their gigantic sizes.
By quantity, nearly all the solar system appears to be an empty void. But, this”vacuum of space” encircles the interplanetary medium containing a variety of kinds of energy, dust, and gas. The stream of gas and charged particles called plasma, mostly protons and electrons, is known as the solar wind. Its speed is about 250 miles (400 km ) per second in the vicinity of the planet’s orbit.
The entire solar system, together with the stars visible on a clear night, orbits the center of our home galaxy known as the Milky Way, which is a spiral disk of 200 billion stars.