The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. Of the many objects that orbit the Sun, most of the mass is contained within eight relatively solitary planets whose orbits are almost circular and lie within a nearly flat disc called the ecliptic p . The four smaller inner planets, Mercury,Venus, Earth and Mars, also called the terrestrial planet, are primarily composed of rock and metal. The four outer planets, the gas giants are substantially more massive than the terrestrials. The two largest, Jupiter and Saturn, are composed mainly of hydrogen and helium; the two outermost planets, Uranus and Neptune, are composed largely of ices, such as water, ammonia and methane, and are often referred to separately as "ice giants".(www. Wikipedia.com)
The Solar System is also home to a number of regions populated by smaller objects. The asteroids belt, which lies between Mars and Jupiter, is similar to the terrestrial planets as it is composed mainly of rock and metal. Beyond Neptune's orbit lie the Kuiper belt and scattered disc; linked populations of trans-Neptunian is object composed mostly of ices such as water, ammonia and methane. Within these populations, five individual objects, Ceres, Pluto, Haumea, Makemake and Eris, are recognized to be large enough to have been rounded by their own gravity, and are thus termed draft planets. In addition to thousands of small bodies in those two regions, various other small body populations, such as comets, centuars and interplanetary gas, freely travel between regions. Six of the planets and three of the dwarf planets are orbited by natural satellites, usually termed "moons" after Earth's Moon. Each of the outer planets is encircled by planetary rings of dust and other particles.(www. Wikipedia.com)
As you travel outward from the Sun, Mercury is the closest planet. It's orbits the Sun at the average distance of 58 million km. Mercury is airless and so without significant atmosphere to hold in the heat, it has dramatic temperature differences. Mercury is also the smallest planet in the Solar System, measuring just 4879 km across the equator. Mercury has only visited two times by spacecraft. The first was Mariner 10, back in the mid 1970s. It wasn't until 2008 that another spacecraft from the Earth made a close flyby of Mercury, taking new image of it's surface.
Venus is the second planet in the Solar System, and it's an almost virtual twin of the Earth in terms of size and mass. Venus orbits at an average distance of 108 km, and completes and orbit around the Sun every 224 days. Apart from the the size, though,Venus is very different from the Earth. It has an extremely thick atmosphere made almost entirely of carbon dioxide that cloaks the planet and helps heat it up to 460 degree Celsius.Several spacecraft have visited Venus, and a few landers have actually made it down to the surface to sent back images of the hellish landscape.The Earth is our home, the third planet from the Sun. It's orbit the Sun at an average distance of 150 km. Earth is the only planet in the Solar System known to support life. This is because our atmosphere keep the planet warm from the vacuum spaces, but it's not so thick that we have a runaway green house effect. No planet in the Solar System has been studied as well as Earth, both the ground and the space. Thousands of spacecraft have been launched to study the planet, measuring it's atmosphere. land masses, vegetation, water, and human impact Earth has only a single moon.
Mars the fourth closest planet to the sun, the second smallest planet in the Solar System.The planets itself was named Mars after the Roman god of war. It has also be been referred to as the red planet because of its reddish appearance.
Mighty Jupiter is the biggest in our Solar system and the fifth planet from the Sun. It is two and half times larger and then all the other planets in solar system combined. Jupiter is primary composed of hydrogen with a minute portion of helium.
Saturn is the 6th planet from the Sun, and the 2nd largest in the solar system.It orbit the Sun at average distance of 1.4 billion km. The most amazing feature of Saturn is it's ring. These are made of particles of ice ranging in size from a grains of sand to the size of a car. Saturn has been visited by spacecraft 4 times: Pioneer 11, Voyager 1 and 2 were just flybys Cassini has actually gone into orbit around Saturn and has captured thousands of images of the planet and it's moon. And speaking moons,Saturn has a total of 60 moons discovered so far. Next comes Uranus, the 7th planet from the Sun. It orbits the Sun at an average distance of 2.9 billion km.Uranus was the first planet to be discovered with a telescope, it was first recognize as a planet in 1781 by William Herschel.
Neptune is the 8th and final planet in solar system, orbiting at an average distance of 4.5 kilometer from the Sun. It's the 4th largest planet, measuring about 49,000 km across.It might not be as big as Jupiter, but it's still 3.8 times larger than Earth. Neptune has only visited by one spacecraft, Voyager 2, which made a fly by in August 1989.Neptune has 13 known moons.
And those are the planet in the Solar System. Unfortunately, Pluto isn't a planet anymore.
