How Many Planets are There?

Solar system is a minute component of the vast universe which was formed billions of years ago. Basically, the solar system consists of the Sun and several celestial bodies revolving around it. These celestial bodies include planets (and their satellites), asteroids, meteoroids etc. Until 2006 the number of planets in our solar system was nine, but the exclusion of Pluto has left the solar system with only eight planets.

Planets in Our Solar System

Sun is the center of our solar system, and has eight planets orbiting it. These planets include, starting from the nearest planet to the Sun, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. Initially regarded as a planet, Pluto was officially declared a dwarf planet by the IAU in 2006, thus, bringing the number of planets in the solar system down to eight from nine. Let's have a brief look at each of these planets in the solar system.

Mercury: Mercury is the smallest planet in our solar system. At 3031.670 mi, its diameter is 38 percent of the diameter of Earth. It has extreme climate with temperature ranging between -180 to 430 degree Celsius. It is located at a distance of 0.39 AU. On the basis of information sent by Mariner 10 spacecraft, scientists suspect that some volcanic activity is occurring on Mercury.

Venus: Venus is a small, rocky planet in our solar system, typically characterized by a thick blanket of yellowish clouds of sulfuric acid. With a diameter of 7521.076 mi, Venus is bigger than Mercury, but smaller than Earth. It is located at a distance of 0.72 AU from the Sun, and has an average temperature of 465 degrees Celsius. Venus is also referred to as the morning star or the evening star, owing to the probability of its sighting at dawn and dusk.

Earth: Earth is undoubtedly one of the most amazing planets of our solar system. The diameter of planet Earth is 7926.210 mi. It is 1 AU away from the Sun, owing to which its temperature ranges between -89 to 58 degrees Celsius. The moon of the Earth plays an important role as far as the gravitational force is concerned. Approximately 71% of the planet is covered with water, while the remaining 29% is land. Its physical properties make planet Earth the only planet to support life form in the Solar system.

Mars: Mars, smaller than planet Earth, is the fourth planet in the solar system. It is also referred to as the 'Red planet' due to the distinct reddish appearance it gets from the presence of iron oxide on it. Its diameter is 4217.246 mi, and has 2 moons revolving around it. It is located 1.52 AU away from the Sun, due to which its temperature ranges between -82 to 0 degree Celsius, making it a cold and lifeless planet.

Jupiter: Jupiter is a giant gas planet, which holds the distinction of being the largest planet in the solar system. With a diameter is 88731.806 mi, it is so large, that a thousand planets the size of the Earth can fit inside it with immense ease. It is located at a distance of 5.20 AU from the Sun, and has a temperature of -150 degree Celsius. With 63 moons revolving around it, Jupiter is quite popular as the planet with most number of moons.

Saturn: Saturn, with a diameter is 74564.543 mi, is the second largest planet in the solar system, next only to Jupiter. It lies at a distance of 9.54 AU from the Sun, and hence its temperature is -170 degree Celsius. It has the second most number of moons, 60 to be precise, next only to Jupiter. It is composed of material which is much lighter than water. The planet is famous for its unique planetary ring system.

Uranus: Uranus is the seventh and the third-largest planet in the solar system. Its diameter is 31763.252 mi and temperature is -200 degree Celsius. It is located at a distance of 19.18 AU from the Sun and it has 27 moons and 13 rings of dark particles, varying in size, around it. The planet is mostly composed of rock and ice. Unlike the other planets which spin right side upwards, Uranus is a bit tilted and spins sideways, which makes it a unique planet in the solar system.

Neptune
Neptune is the last planet in our solar system, since Pluto has been officially classified as a dwarf planet. Its diameter is 30775.272 mi and temperature is -210 degree Celsius. It's located at a distance of 30.06 AU from the Sun and mostly composed of ice and rock, Neptune has 13 moons and reddish planetary rings around it. A trip by Voyager 2 in 1989, the only visit by a spacecraft on Neptune, is the only source of credible information we have about Neptune.

Exclusion of Pluto from the list has left the solar system with only eight planets. Pluto was classified as a planet since its discovery in 1930, but in 2006, it was re-classified as a 'dwarf planet' by the International Astronomical Union (IAU). According to the IAU, dwarf planet is a celestial body orbiting the Sun, which is massive enough to be rounded by its own gravity, but not capable of clearing its neighboring region of the planetesimals. Other dwarf planets identified by IAU include Eris, Ceres, Haumea and Makemake.