Our solar system consists of the Sun and eight planets. Earth, the planet we live in, revolves around the Sun along with other planets. If earlier we knew that there were nine planets, now the planet Pluto is no longer classified as a planet.
Reporting from the International Astronomical Union page, iau.org reports that Pluto was first discovered in 1930. Pluto is a freezing cold world, billions of kilometers away from Earth, and thirty times lighter than the planet formerly known as the smallest planet, Mercury.
The landscape of the Solar System began to change with the discovery of an object classified as a Trans-Neptunian Object (TNO) on 30 August 1992, whose size was .
With more and more discoveries of Trans-Neptunian Objects (TNOs), it seems inevitable that eventually an object will be discovered that rivals Pluto in size.
Follow-up observations showed that the object was larger than Pluto and also had a satellite. With the discovery of an object farther from Neptune with a size and mass greater than Pluto, and the continued search for trans-Neptunian objects, many astronomers have begun to wonder: “What exactly is a planet?”
As of 24 August 2006 the definition of planets in the Solar System was approved as follows:
- A supernatural object that:
- revolve around the sun
- Its mass is so large that its own gravity is able to oppose the rigid-body force due to which the object’s shape shows hydrostatic equilibrium (a nearly spherical shape).
- has “cleared” any other object in the vicinity of its orbit.
From the results of the IAU resolution, there are officially eight planets in the Solar System, namely Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.
Nevertheless, astronomers are still looking into the possibility of a ninth planet after Pluto’s removal. As of 2016, a planet was found which was later called Planet Nine or Planet X and was said to be 10 times larger than Earth and 5000 times the time of Pluto.
Following is the order of the planets in the Solar System after Pluto was removed:
1. Mercury
It is the smallest planet in the solar system. Mercury’s temperature becomes very high during the day, while it is very cold at night. Mercury makes one complete revolution around the Sun in 88 days.
Mercury has several large craters on its surface that are believed to be the result of meteorite impacts.
2. Venus
The size of Venus is almost like Earth, even humans cannot live on this planet because its atmosphere is full of carbon dioxide which cannot be used for breathing.
Venus is shrouded in clouds of deadly sulfuric acid. Venus rotates in the opposite direction to the other planets. The rotation is also very slow. One day on Venus is equal to 243 days on Earth.
3. Earth
Earth is the only planet in the solar system on which living beings live. Life exists because there is liquid water on our planet where two thirds of the surface is covered by water.
The sun is also at the right distance to provide the right amount of heat, so that people don’t get too hot or cold in extreme weather.
Earth is also surrounded by a gas called atmosphere which provides air to breathe and protects us from the impact of meteorites.
4. Mars
Mars is called the Red Planet because of the accumulation of dust on its surface. Mars is about half the size of Earth. It is possible that Mars once had a river because its surface has many traces of dry rivers, deep valleys and pre-coastal plains. If that were the case, maybe there would be life there. But at present Mars has underground water only at the north and south poles of Mars or in other parts.
Mars orbits the Sun in 687 days.
5. Jupiter
Jupiter is the largest planet in the solar system. On a rocky hard surface like Earth. The red, white, brown, and yellow stripes are thick clouds beneath Jupiter’s stormy atmosphere.
The big red dot on the surface of Jupiter is 3 times bigger than Earth. It was actually a huge storm that was raging for 300 years. Jupiter orbits the Sun in 11.9 Earth years.
6. Saturn
Saturn is no bigger than Jupiter, but it is a giant nonetheless. The planet is surrounded by wide rings of rock and ice cubes. Saturn is a “gas giant” whose dense atmosphere consists of hydrogen. It takes 29.5 Earth years to revolve around the Sun but a day on Saturn is shorter than on Earth because it rotates faster
7. Uranus
Uranus is the third largest planet and is mostly gas. Uranus is unusual because of its tilted axis of rotation. It takes 84 Earth years for one complete rotation. Like Saturn, Uranus is surrounded by rings but is thinner.
8. Neptune
Neptune is the fourth largest gas giant. It has many dark rings that are thinner because it is farther away from the Sun. It is very cold and one of its satellites, Triton, is the coldest object in the Solar System.
Neptune orbits the Sun every 165 years.
This is the order of the planets in the current Solar System without Pluto.
