What Is A Planet?
A planet is a celestial object that orbits around the sun and together with other planets forms the solar system. The name planet is derived from Greek word for wanderer. Before the invention of the telescope, planets were seen as object wandering in the sky. Technological advancements have helped scientists to significantly increase their knowledge regarding planets by sending spacecraft, and also from better observations that can now be made from the ground. Our solar system has 8 known planets, although initially there were considered to be nine following the 1930s when Pluto was discovered. However, in the 1990s Pluto was demoted to the status of a dwarf planet rather than a true planet.
Jupiter is the biggest planet known among all the eight planets that orbit the Sun. Its radius is 69,911 kilometers. It is so gigantic that all other planets could fit into Jupiter. It is the fifth planet from the sun. Its name was derived from the Roman king of gods. Its atmosphere is composed of gasses mainly hydrogen and helium. Jupiter’s surface is made of an ocean of liquid hydrogen.
Jupiter appears to have white, yellow, thick red and brown clouds. These clouds move around the planet at high speeds in the opposite direction as the planet spin on its axis. The largest of these storms is the Great Red Spot which move around the equator at high speed that resembles a hurricane.
Jupiter has the strongest magnetosphere of all other planets, nearly 20,000 times that of Earth. Jupiter rotates on its axis faster than any other planet in just less than 10 hours. Jupiter has three faint rings composed of dust particles which result from the impact of comets and asteroids. The planet revolves around the sun once in a period of 11.86 Earth years.
The planet Saturn has a radius of 58,282 kilometers and is ranked second regarding planet size. This radius is not inclusive of its rings. It is easily visible to the naked eye and is the sixth planet from the sun. Its discovery is not credited to any one person. It was named after Saturnus the Roman gods. It rotates on its axis every 10 hours and 34 minutes and orbits around the sun in 29.4 Earth years. Its atmosphere has three layers, the first layer is composed mostly of ammonia ice, and the second layer is made of water ice, while a mixture of hydrogen and sulfur makes up most of the third layer.
Saturn is mostly made of hydrogen. It has thin and extensive rings made up of particles of ice and small chunks of carbonaceous dust. These particles are thought to be results of asteroids, moons, and comets breaking apart in Saturn’s vicinity. The planet is 1,424,600,000 kilometers away from the Sun. Saturn has 62 known moons and is the flattest planet largely because of its low density and fast rotation speed.
The existence of the planet Uranus is credited to a British astronomer William Herschel. It was an unprecedented discovery made on March 13, 1781.In regards to distance from the sun, Uranus assumes the seventh position preceding only the planet Neptune. Uranus is ranked third in regards to size of the planets with a mean radius of 25,362 kilometers. Its name was derived from the ancient Greek deity of the sky called Ouranos. It takes Uranus 17.24 Earth days to spin on its axis. Uranus orbits around the Sun in 84 Earth years. Uranus and Venus are the only two planets out of the eight known planets that follow a clockwise path while orbiting around the Sun. 80% of the Uranus planet is composed of ice. Uranus has a pale blue color because of the presence of water, ammonia, and methane ice on its outer atmosphere. It has a hydrogen and helium layer underneath this upper atmosphere. The planet has a core of iron and magnesium silicate.
Of all known planets, Neptune is the most distant from the Sun.It was discovered on September 23rd, 1846, by Johann Gall. The discovery was facilitated by prior information from a French astronomer Urbain Le Verrier and another independent British astronomer named John Couch Adams. It orbits the Sun in 164.79 Earth years and has 14 moons has five faint rings.
Neptune is a gas planet made mostly of hydrogen, helium, and methane. The methane in the atmosphere absorbs red light in substantial quantities such that Neptune appears to be the color of azure blue. The name Neptune can be traced to Roman mythology where Neptune was the name given to a god the Romans believed to be the sea. The planet’s core is mainly made of rock. It has a massive violent storm called the Great Dark Spot. The climate on Neptune is very active with large storms and winds swirling around it at high speeds. Only one spacecraft has been sent to Neptune in 1989 called the Voyager 2.
Other Planets and the Case of Pluto
Other planets, by their size, include Earth with a radius of 6,371 kilometers, Venus with a radius of 6,052 kilometers, Mars with a radius of 3,390 kilometers, and Mercury with a radius of 2,440 kilometers. Notably missing from the list is Pluto, which ceased to be considered a planet in 2009. A new definition of planets was made by astronomers who required them to meet 3 criteria. The third criterion states that a planet must have enough gravitational force to clear the neighborhood of its orbit of other objects. Objects in the Kuiper Belt, which is in Pluto's vicinity, have been discovered and therefore it was disqualified from the list of planets.
Biggest Planets In Our Solar System