Our solar system consists of the Sun, which is about 4.5 billion years old, four planets (Mercury, Venus, Earth and Mars) that are part of the inner solar system, the asteroid belt (which should've formed a planet but were ripped apart by Jupiter's gravitational field whenever they tried to clump together), four gas giants (Jupiter, Saturn, Uranus and Neptune), the Kuiper Belt, the Oort Cloud, and any celestial body also in orbit around the Sun (comets and meteoroids). The eight planets orbit the Sun on the same plane, which is called the ecliptic plane. Several other celestial bodies such as Pluto, do not orbit the Sun on this plane, sometimes crossing above and below some of the planet's orbital paths. 

 

The Sun contains 99.8% of our solar system's mass - it's almost 10 times bigger than Jupiter! One of the most important functions of the Sun is to protect the solar system from cosmic rays and dust beyond the solar system. This occurs because the Sun releases a stream of charged particles called the solar wind which creates a bubble, called the heliosphere, around the solar system, which blocks the cosmic rays and dust from entering the solar system. If it were possible for these cosmic rays to enter the solar system, they could damage Earth's ozone layer, damage our DNA causing mutations or an increased risk of cancer and trigger an ice age by dimming the sunlight. 

 

The four terrestrial planets, Mercury, Venus, Earth and Mars, which make up the inner solar system, are made mostly from rocks and metals with higher boiling points, which allowed them to stay solid within the heat of the inner solar system. 

 

The asteroid belt lies between the orbits of Mars and Jupiter. Like the terrestrial planets, these objects are also made from rocks and metals. On January 22, 2014, scientists from the European Space Agency announced the discovery of water vapour on Ceres, the largest object in the asteroid belt. This discovery was significant because comets, not asteroids, usually have water vapours coming from them. Astronomers are beginning to realize that the difference between comets and asteroids are becoming more blurred.

 

After the asteroid belt comes the gas giants (Jupiter, Saturn, Uranus and Neptune). Jupiter and Saturn are comprised mainly of hydrogen and helium, while Uranus and Neptune are comprised mainly of water, ammonia and methane. These substances are called "ices". This is why Uranus and Neptune are sometimes classified into a subcategory of "ice giants". 

 

Past the orbit of Neptune lies the Kuiper Belt - a collection of icy bodies, that could've formed into another planet, but because of Neptune's gravitational pull, these icy bodies were not able to clump together into a planet (much like the asteroid belt and Jupiter). Since 2006, astronomers have also observed in 9 other solar systems circumstellar discs similar to our own Kuiper Belt. Since the Kuiper Belt objects (KBOs) are constantly colliding with each other they are slowly grinding down to dust, and according to Micahel Brown, a professor at the California Institute of Technology, the Kuiper Belt will cease to exist in 100 million years.

 

The Oort Cloud is basically a region of our solar system that is giant cloud of ice surrounding the entire solar system. Whike astronomers have no concrete evidence that the Oort Cloud exists, since it has never been seen before, astronomers all acknowledge the existence of the Oort Cloud since it answers many questions such as, "Where do comets come from?" The theory of the Oort Cloud came from Jan Oort who was trying to answer the question above, "Where do comets come from?" Since comets eventually burn up and disappear after several trips around the Sun, Jan Oort wanted to know why new comets kept on coming. Due to his calculations Oort realized that the long-period comets (like Hale-Bopp) came from a reservoir of comets located at the outer-edges of our solar system. The Oort Cloud could hold up to 2 trillion objects made of water, ammonia and methane (ices).