1. Do Now:
What do you already know about the different kinds of planets in our solar system? Do you already know something specific about them?
Write about what you see in the diagram of the solar system below:

2. The Solar System
The Planets

3. Our Solar System Formed around 4.6 billion years ago.
Centered around our sun, a “G-Type Main Sequence Star,” informally known as a yellow dwarf.
8 Planets revolve around it, (4 rocky inner planets & 4 gas giants), along with many other asteroids, comets and dwarf planets.

4. How did it form?
Our solar system formed around 4.6 billion years ago when a cloud of space dust and particles, (called a nebula), collapsed in on itself.
This most likely occurred from the shockwave of a nearby star exploding upon it’s death, (supernova).
This collapse caused particles to get very compressed and hot, so much so that fusion began to occur and our sun was formed.
The remaining particles formed a disc around this sun, held by gravity, and as they rotated around it, collisions between these particles formed larger and larger masses, eventually forming the planets and other bodies in the system.

5. Terrestrial Planets Commonly referred to as the ‘rocky’ inner planets.
The 4 smaller, solid, rocky planets located on the inner circles of the solar system, closer to the sun.
Include, (in order from the sun): Mercury, Venus, Earth and Mars.

6. Terrestrial Planets
All likely formed when particles from early solar system collided to form larger masses, eventually coalescing into the four major bodies that became the rocky inner planets.
There were likely other bodies like these forming in the early solar system, but they all either collided and merged with the existing four planets or were broken apart and became part of the asteroid belt.

7. Terrestrial Planets: Facts
All have the same general structure, with a central, solid core made primarily of iron and other heavy metals, surrounded by a molten mantle.
Can have canyons, craters, mountains, volcanos, etc., based on the presence of water and tectonic activity.
All have some form of secondary atmosphere, formed from volcanic activity, comet impacts and/or presence of water, held to planet by gravity.

8. Gas Giants Sometimes referred to as the Jovian Planets, after Jupiter.
The 4 much larger, gaseous planets composed primarily of Hydrogen and Helium located on the outer circles of the solar system, farther from the sun.
Include, (in order from the sun): Jupiter, Saturn, Uranus and Neptune.

9. Gas Giants
All likely formed from the gasses and lighter elements that coalesced in the pressure of the early solar system.
All of the gas giants exist farther away from the sun, (and the rocky planets are all closer to it), because the lighter and often cooler gaseous and icy materials could not exist close to the sun. Only the heavier, rockier elements could. Therefore, the heavy rocky particles coalesced into the terrestrial planets close to the sun, and the gases and icy particles coalesced farther away from the sun, forming the gas giants.

10. Gas Giants: Facts
Jupiter and Saturn are made mostly of Hydrogen and Helium, while Uranus and Neptune are made of slightly heavier, more volatile elements, commonly referred to as ‘ices’ which has earned them the special title of ice giants.
Gas giants consist of a large outer layer of lighter gases, followed by a layer of molten or metallic hydrogen or helium, with a speculated molten, rocky core, (though little is known about this).
All gas giants have many outer cloud layers made of lighter elements in continuous motion, convection and cycling, held to the planets by gravity.

11. Compare and Contrast: Terrestrial Planets vs. Gas Giants