1. The Sun and the Motions of Objects in the Solar System
Expectations: D3.4, D3.5

2. The Sun
Our Star!
Emits energy (radiation) some of which is absorbed by the Earth’s atmosphere and some is reflected into space
This radiation is the driving force behind our weather and climate and provides energy for life to exist

3. Structure
At the core, nuclear fusion occurs (H fuses to He), it is the hottest part of the Sun ( ºC)
First layer –radiative zone
Second layer- convective zone
Third layer- photosphere (5500ºC)
Sun’s atmosphere includes the chromosphere (65 500ºC) and corona (halo that extends millions of km)

4. Structure of the Sun

5. Effects on Earth Auroras Shifting colours in the sky
Due to collisions between solar particles & matter in the Earth’s upper atmosphere
Northern lights (aurora borealis)
Southern lights (aurora australis)

6. Northern Lights

7. Aurora Borealis

8. Southern Lights-Aurora Australis

9. Other Effects Communication disruptions and radiation hazards
Particles ejected by the Sun can damage information on satellites, therefore tv and cell phone disruption
Radiation in solar storms can be harmful to astronauts and people travelling in planes

10. Motion of Planets Planets rotate and revolve.
Rotation: the spin on the planets axis.
The Earth takes 24 hours to rotate.
The Sun appears to rise and set because the Earth is spinning.
Revolution: the orbit around the sun.
The Earth takes days to orbit the Sun.
The reason we have seasons is due to the Earth’s tilt (23.5º).

11. Day vs. Night

12. Seasons

13. Geocentric Model
2000 years ago, Ptolemy believed that the Sun and the planets revolved around the Earth. This is the geocentric model.

14. Geocentric Model

15. Heliocentric Model
Copernicus ( ) proposed a model of the Solar System with planets revolving around the Sun. In the early 1600s Galileo investigated planets with moons orbiting them to confirm that the geocentric model was incorrect. Kepler added the idea that planets travel in ellipses around the Sun not circular pathways.

16. Heliocentric Model

17. Homework
Page 312 # 7
Page 328 # 2, 3, 8-10