Our Solar System!

How did the Solar System form? From looking at other star systems forming, scientists think our solar system started as a big cloud of dust called a nebula!

As the dust particles collided and stuck together, they started to have gravity. The gravity pulled the dust towards the center of the nebula!

Colliding particles created a spark, and the center exploded into flames! Much of the gas near the sun got burned off, leaving the inner planets to form small and made mostly of metal and rock.

The outer planets were able to keep their gas, but have metal and rock cores about the size of the inner planets.

It is believed that if Jupiter had acquired more gas, it could have become a second sun! Most star systems are binary (have two suns)

So.... How many planets are there in Sol’s system? And what order are they in?

There are 4 inner planets made of rock and metal: Mercury, Venus, Earth, Mars.

We think there may have once been a FIFTH inner planet, that got smashed! All we have now is an asteroid belt of small chunks of rock past Mars!

Then there are the four gas giants: Jupiter, Saturn, Uranus, and Neptune.

Beyond the gas giants there is a second asteroid belt! It is called the Kuiper Belt. This belt was not originally part of the solar system, but was trapped by its gravity!

Some Kuiper asteroids are big enough that people thought they should be planets! But they aren’t from here, and have really different orbits than our eight planets...

You can see where Pluto got pulled out of the Kuiper Belt by gravity... And Pluto’s WAY different orbit!

Around our whole Solar System is the Oort Cloud! This cloud of cosmic debris is where most of our comets come from!