1. Our Solar System!

2. 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!

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

4. 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.

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

6. 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)

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

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

9. 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!

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

11. 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!

12. 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...

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

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