2. The Sun 99.8% of the mass of the solar system is in the Sun.
It controls the motion of all objects in the solar system.

3. Mercury Mostly solid and covered with craters.
Its small size (smallest planet) and high density suggest a large iron and nickel core.
Its atmosphere is constantly being replenished and destroyed by solar wind.
This causes extreme temperature fluctuations (-173o C to 427o C)

4. Venus
Venus is similar in size and composition to Earth (slightly smaller).
Thick clouds of CO2 and sulfuric acid cover the planet causing an intense greenhouse effect (464o C).
Retrograde motion – Venus rotates clockwise very slowly (day is longer than year).

5. Earth Earth is the largest rocky planet and the most dense.
Unique properties that allow for life:
Presence of liquid water because:
Distance from the Sun
Nearly circular orbit
Mild greenhouse effect
Protection from radiation:
Atmosphere absorbs/reflects radiation
Magnetic field
One moon.

6. Mars Mars is the 2nd smallest planet.
Because if it’s small size and density, Mars has a thin atmosphere that contains mostly carbon dioxide.
Water may have once existed when Mars had a thicker atmosphere.
Mars has two small moons.

7. Moons of Mars
Phobos
Deimos

8. Jupiter The largest planet (1/10th diameter of the Sun)
Composed mostly of hydrogen and helium (liquid core, gaseous atmosphere).
Has over 60 moons including four large moons.
The Great Red Spot, a huge atmospheric storm that has lasted for at least 300 years.

9. Europa It is slightly smaller than the Earth’s moon.
There may be liquid water under the ice due to gravitational heating.
Europa is one of the five known moons in the solar system to have an atmosphere.

10. Saturn 2nd largest planet.
Saturn is less dense than water (H & He). If you could fit Saturn in a lake, it would float!
Rings are leftover debris from asteroid collisions.
250,000 km or more in diameter, but less than 200 meters thick.

11. Saturn’s Moon - Titan Larger than Mercury.
Dense atmosphere with nitrogen and methane.
Cassini probe detected ice and water vapor.

12. Uranus 3rd largest planet.
Also mostly H & He but appears blue-green because of the methane in its atmosphere.
Faint rings detected only because they block starlight.
Knocked sideways by a large passing object.

13. Neptune 4th largest planet and furthest from the sun.
Existence predicted before it was discovered.
Like Uranus, the methane gives Neptune its color.

14. Pluto Not a planet. Why? Smaller than our moon.
Comet like composition - rock and ice.
Irregular orbit.
One of many similar objects in the outer reaches of the solar system - dwarf planets.