Planets In Our Solar System
Planets in Our Solar System, A solar system is essentially a star and the objects that orbit around it. Our solar system consists of the Sun in the centre around which eight planets, a dwarf planet and some asteroids revolve. Our solar system is in an outward portion of the Milky Way galaxy. Let’s have a look at the planets in our solar system.
The planets in our solar system were discovered after astronomers followed moving points of light among the stars. Mercury, Venus, Jupiter, Mars and Saturn were discovered in a similar manner, while Neptune, Uranus, Pluto, the Asteroid Belt and the moons of many planets were observed only after the telescope was invented. The discovery of the dwarf planet Eris led to the discovery of other dwarf planets. Several space probes were sent out in space to further explore the solar system and are being continued today.
Solar System Theorised
The solar system is theorised to have originated from a giant rotating cloud of dust and gas known as the solar nebula. This nebula collapsed due to its gravity. It spun faster and was flattened to a disc. Most of the material from this nebula moved towards the centre and formed the sun. Other particles collided and stuck together to form planetesimals (objects that are the size of asteroids). Some of these planetesimals combined to form comets, asteroids, moons, and planets. The solar winds were very powerful and swept away lighter elements such as helium and hydrogen from the inner planets. The solar winds were much weaker in the outer planets and hence, they are predominantly made of helium and hydrogen.
In the order of their distance from the Sun, the planets in our solar system are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. In the year 2006, The International Astronomical Union classified Pluto as a dwarf planet and it is effective, not included in this list. Apart from the planets, it also includes meteorites, comets, asteroids, a disc-shaped Kuiper Belt, a spherical Ort Cloud and a heliopause that is shaped like a teardrop. The solar system is estimated to stretch for a distance of 9 billion miles.
Evidence for a new planet nicknamed “Planet x / Planet 9” was unveiled in 2016 bringing the number of planets in the solar system back to nine. It is estimated to have a mass that is 5,000 times that of Pluto and 10 times that of Earth. This planet x (video) is believed to exist between Neptune and Pluto. In any case, Pluto is the farthest object in our solar system orbiting in an elliptical and completely tilted axis.
The sun lies at the centre of our solar system and is by far, the largest object in it. It contains around 99.8% of the mass in the entire solar system. It provides light and heat without which life on Earth would stop. Most of the other objects in the solar system orbit in oval-shaped paths, with the sun slightly off centre from their paths.
Kinds of Planets
The planets in our solar system are of two kinds. The first kind is Terrestrial planets or planter whose surfaces are rocky. This includes Mercury, Venus, Earth and Mars. The other four are called Jovian planters because they are huge in comparison to the terrestrial planets and more importantly, are gaseous in nature. Jupiter and Saturn are basically called gas planets while Uranus and Neptune have more ice. A common feature is that all four planets contain helium and hydrogen.
Pluto also has solid rocky surfaces. But since it has been classified as a dwarf planet, it falls out of this list. The IAU defines a planet that can circle the sun without being the satellite of any other object while being large enough so that it can be rounded (by its own gravity) and must ‘clear the neighbourhood’ of other orbiting objects. The problem with Pluto is its small size and its odd orbit when compared with the other planets in our solar system. Most importantly, Pluto’s orbit shares space with other object belonging to the Kuiper Belt that lies beyond Neptune. Other dwarf planets are Eris, Makemake, Sedna and Haumea from the Kuiper Belt and Ceres from the Asteroid Belt that lies between Jupiter and Mars.
Comets are comprised of primarily rock and ice. They follow very long orbits that bring them closer to the sun at certain points. Some short-period comets are thought to originate from the Kuiper belt and complete their orbits within 200 years. Long-period comets take more than 200 years to complete their orbits and they are believed to have originated from the Oort Cloud. When comets come very close to the sun, some of the ice in their central nucleus evaporates into gas which is carried outward, giving it a characteristic ‘tail’.
The Kuiper belt is long suspected to exist beyond Neptune and is estimated to house more than a trillion comets and some hundreds of thousands of icy bodies. Beyond this lie the Oort Cloud, Heliosphere and Heliopause.