Now You Know

Facts About The Planets In Our Solar System

MERCURY: No known moons. Has a surface temperature of -173 to 427 degrees Celsius. (-279 to 752 degrees Fahrenheit). It was first recorded in 14th century BC by Assyrian astronomers. A year in Mercury is only 88 days long. It's the smallest planet in the Solar System. It's the 2nd densest. It has wrinkles on its surface- as the iron core of the planet cooled and contracted, the surface of the planet became wrinkled. These wrinkles are called Lobate Scarps, and can be up to a mile high and hundreds of miles long. It's the 2nd hottest planet, with temperatures up to 427 degrees Celsius (752 degrees F.). 

VENUS: No known moons. Has a surface temperature of 462 degrees Celsius (864 degrees Fahrenheit). It was first recorded in 17th century BC by Babylonian astronomers. One day on Venus is longer than our year. It's often called Earth's sister planet. It rotates counter clockwise. It's the 2nd brightest object in the night sky. The atmosphere pressure on Venus is 92 times greater than Earth's. The hottest planet in our system with temperatures up to 462 degres Celsius.

EARTH: Rotation is gradually slowing. It was once believed to be the center of the universe. It has a strong magnetic field. It also has the greatest density.

MARS: 2 known moons- Phoebes and Deimos. Has a surface temperature from -87 to -5 degrees Celsius (-125 to 23 Fahrenheit). It was first recorded in 2nd millenium BC by Egyptian astronomers. Mars and Earth have approximately the same landmass. It's home to the tallest mountain in the entire Solar System with a height of 21 km and a diameter of 600 km (height of 13 miles and a diameter of roughly 373 miles), and is called Olympus Mons. It has the largest dust storms in the solar system- they can last for months, and cover the entire planet! The sun appears half the size as on Earth. Pieces of Mars have fallen to the Earth.

JUPITER: 67 known moons- the most notable, being Io, Europa, Ganymede, and Callisto. Has 4 known rings. Has surface temperatures of -108 degrees Celsius (-162 Fahrenheit). It was first recorded in 7th/8th century BC by Babylonian astronomers. It's the 4th brightest object. It has the shortest day of all the planets. It orbits the sun every 11. Earth years. It has unique cloud features- the upper atmosphere of Jupiter is divided into cloud belts and zones- they are primarily made of ammonia crystals, sulfur, and mixtures of 2 compounds. The Great Red Spot is a giant storm- it's raged on for at least 350 years... it's so large, 2 Earths could fit inside it. Jupiter's interior is made of rock, metal, and hydrogen compounds- below its massive atmosphere (primarily made of hydrogen), there are layers of compressed hydrogen gas, liquid metal hydrogen, and a core of ice, rock, and metals. Jupiter's moon Ganymede is the largest moon in the system- larger than the planet Mercury. Jupiter has a thin ring system.

SATURN: 62 known moons, the most notable being Titan, Rhea, and Enceladus. Has surface temperatures of -139 degrees Celsius (-218 Fahrenheit). Was first recorded in 8th century BC by Assyrians. Has 30+ rings. It can be seen with the naked eye. It's the flattest planet. It orbits the sun every 29.4 Earth years. Its upper atmostphere is divided into bands of clouds- the upper layers are mostly ammonia ice; below them, the clouds are largely water ice; below are layers of cold hydrogen and sulfur ice mixtures. It has oval shaped storms similar to Jupiter's- it also has a vortex over its south pole that resembles a hurricane-like storm. Saturn is made mostly of hydrogen. It has the most extensive rings in the solar system, made mostly of chunks of ice and small amounts of carbonaceous dust- they stretch out more than 120,700 km (75,000 miles) from the planet, but are amazingly thin- only 20 m (66 ft) thick. Saturn has 150 moons and smaller moonlets- all are frozen worlds, the largest being Titan and Rhea... Enceladus appears to have an ocean below its frozen surface.

URANUS: Has 27 known moons, the most notable being Oberon, Titania, Miranda, Ariel and Umbriel. Has 13 known rings. Has surface termperatures of -197 degrees Celsius (-323 Fahrenheit). It's discovery date was March 13, 1781 by William Herschel. It makes one trip around the sun every 84 Earth years. It's often referred to as the Ice Giant. It's the coldest planet in the system, with temperatures dropping down to -224 degrees Celsius (-371 Fahrenheit).

NEPTUNE:  14 known moons, the most notable being Triton. 5 known rings. Has surface temperatures of -201 degrees Celsius (-330 Fahrenheit). It's discovery date was September 23, 1846 by Urbain Leverrier and Johann Galle. It's the smallest of the ice giants. The atmosphere is made of hydrogen and helium with some methane. It has a very active climate with large storms in the upper atmoshere, and it has 14 moons.

PLUTO: (Authors Note- I am including Pluto because it was part of our System for eons before scientists ruled it NOT a planet, so I'm including the poor little guy in here. To me, Pluto is still a planet of our Solar System.) 5 known moons, the most notable being Charon, Nix, Hydra, Kerberos, and Styx. Has surface temperatures of -229 degrees Celsius (-380 Fahrenheit- even colder than Uranus). It's discovery date was February 18, 1930 by Clyde W. Tombaugh. Pluto was reclassified from a planet to a dwarf planet in 2006- This is when the IAU formalized the definition of a planet as "a celestial body that (a) is in orbit around the sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium shape, and (c) has cleared the neighborhood around it's orbit". It also sometimes has a solid atmosphere- during its elliptical when it's closer to the sun, its surface ice thaws and forms a thin atmosphere primarily of nitrogen with a little methane and carbon monoxide. When Pluto ltravels away from the Sun, the atmosphere then freezes back to its solid state.

Source: {http://www.space-facts.com/planets/}