1. The Solar System: The Sun & the Planets

2. Measuring Distances in the Solar System
The astronomical unit (AU) is used to measure distances within the Solar System
The average distance from the Sun to Earth is approx km
1 AU = (1.5 x 108) km
Planets Big & Small
The Sun is the largest object in the Solar System, the next largest are the planets.

3. The Inner Planets = Terrestrial Planets
Mercury, Venus, Earth & Mars
Small, rocky planets
Located between the Sun and Asteroid Belt

4. Mercury Location – Inner Orbital Period – 88 days Rotation – 59 days
Atmosphere – None
Temperature – -180 to 400 0C
# of Moons – 0
Rings – 0
Unique Characteristics
No atmosphere to trap heat
Contains craters
Rarely visible in our night sky because it is so close to the Sun

5. Venus Location – Inner Orbital Period – 224.7 days Rotation – 243 days
(opposite direction)
Atmosphere – carbon dioxide,
nitrogen
Temperature – 462 0C
# of Moons – 0
Rings – 0
Unique Characteristics
Brightest object in the sky after the Sun & Moon

6. Earth Location – Inner Orbital Period – 365.26 days Rotation – 24 h
Atmosphere – Nitrogen, Oxygen
Temperature – -88 to 58 0C
# of Moons – 1
Rings – 0
Unique Characteristics
Ozone – filters some of damaging radiation from the Sun
Temperatures are constant
70% of planet’s surface is water

7. Mars Location – Inner Orbital Period – 687 days Rotation – 24.65 h
Atmosphere – Carbon dioxide,
Nitrogen
Temperature – -90 to -5 oC
# of Moons – 2
Rings – 0
Unique Characteristics
Called the ‘red planet’ due to its rusty soil
Very dry
Once had volcanoes, glaciers & water
No signs of life

8. The Outer Planets = Gas Giants
Jupiter, Saturn, Uranus & Neptune
Large, composed of gas
Atmospheres consist mainly of the gases hydrogen and helium

9. Jupiter Location – Outer Orbital Period – 11.9 years Rotation – 9.85 h
Atmosphere
– Hydrogen, helium, methane
Temperature – -148 oC
# of Moons – 63
Rings – Yes
Unique Characteristics
Largest planet (11x the diameter of Earth)
Features are its coloured bands, the Great Red Spot & hurricanes
Orbiting rings of rocks

10. Saturn Location – Outer Orbital Period – 29.5 years Rotation – 10.65 h
Atmosphere – Hydrogen,
helium, methane
Temperature – -178 oC
# of Moons – 60
Rings – Yes
Unique Characteristics
Second largest , no solid core
Cloudy & windy, over 1000 separate rings

11. Uranus Location – Outer Orbital Period – 84.1 years
Rotation – 17.3 h (on it’s side)
Atmosphere – Hydrogen,
helium, methane
Temperature – C
# of Moons – 27
Rings – Yes
Unique Characteristics
Winds blow up to 500 km/h

12. Neptune Location – Outer Orbital Period – 164.8 years
Rotation – 15.7 h
Atmosphere – Hydrogen,
helium, methane
Temperature – C
# of Moons – 13
Rings – Yes
Unique Characteristics
Uneven orbit, Bright blue & white clouds
Has a dark region called the Great Dark Spot, which appears to be the center of a storm

13. Planet Rotations

14. To be considered a “planet” a celestial object must; 1
To be considered a “planet” a celestial object must; 1. Be in orbit around a star (such as the Sun) 2. Have enough mass to be pulled into a stable sphere shape by gravity 3. Dominate its orbit (i.e., its mass must be greater than anything else that crosses its orbit)

15. Dwarf Planets
A celestial object that orbits the Sun and has a spherical shape but does not dominate its orbit.
Ceres, Pluto, Haumea, Makemake, and Eris
Pluto’s tilted orbit crosses Neptune’s orbit

16. Planet Locations

17. Smaller Members of the Solar System
Asteroids
are composed of rock & metal.
Although they orbit the Sun, they are too small to be considered planets.
Most asteroids lie in the asteroid belt, located between Mars & Jupiter.

18. ASTEROID BELT
700,000 to 1.7 million asteroids with a diameter of 1 km or more.
Over 200 asteroids are known to be larger than 100 km.

19. A meteoroid is a piece of metal or rock that is smaller than an asteroid.
Sometimes they get pulled in by Earth’s gravity. They burn up in the Earth’s atmosphere, creating a bright streak of light across the sky, known as a meteor (shooting star).
Larger meteors do not burn up completely in the atmosphere and their remains, which we call meteorites, crash to the ground.

21. DID YOU KNOW?
A leading theory on the extinction of dinosaurs suggests that a 10 km wide meteorite impact is what caused the extinction of these animals 65 million years ago.

22. Wolfe Creek Crater in Australia

23. Comets
Comets are large chunks of ice, dust, and rock that orbit the Sun.
As a comet approaches the Sun, radiation and solar wind from the Sun, causes a gaseous tail to form, pointing directly away from the Sun.
A dust tail forms in the direction from which the comet originated.
Most comets have 2 tails;
gaseous tail
dust tail

24. Comets

26. Homework
WS P.317 #5, 6, 8