1. Chapter 4: Earth and Moon

2. From the Earth, Venus appears as a white planet in the evening sky or the morning sky. From Mars, the Earth might appear as an “evening star” just after this sunset: (photo taken by a Rover on the Mars surface).

4. Just after a sunset on Mars, the Earth appeared as a pale blue planet in the evening sky.

5. A closer look reveals a planet ¾ -covered with liquid water

6. Earth’s Atmosphere is layered.

7. Convection heats the lower atmosphere, distributing heat from the ground.

8. The Greenhouse Effect plays a major role in heating the Earth’s atmosphere. Factors include: Clouds Water vapor Agriculture City “heat islands” Carbon dioxide Methane CFC gases Dust and pollution Snow cover Desertification

9. Global Warming is definitely occurring, but this may be due to several reasons.

10. Global Warming may be due partly to increasing carbon dioxide levels which increase the Greenhouse effect (there is some debate on whether or not this is the cause).

11. Increasing carbon dioxide levels have been measured on the Hawaiian volcano, Mauna Loa.

12. Earth’s interior is revealed by seismology, the study of earthquakes. Layers are revealed: A layered object: Inner core Outer core Mantle Crust Hydrosphere Atmosphere Magnetosphere

13. Observation of Seismic Waves due to earthquakes reveals the interior structure of the Earth

14. Earth’s Interior Mantle is about 80% of the volume of the Earth (basalt) Core is believed to be mostly iron and nickel, but could have many of the heavier elements. There is certainly some uranium and other radioactive elements which produce heat that keeps the core hot and molten. We will compare this structure with other planet’s structures.

15. Global Plates move slowly – plate tectonics The motion at their boundaries causes earthquakes.

16. Himalayas are due to colliding tectonic plates.

17. Californian Fault (San Andreas fault) is where plates are slipping and cause earthquakes.

18. Plate Drift causes many effects: earthquakes, rift valleys, mountain chains, volcanoes, mid-Atlantic ridge, etc.

19. Earth’s Magnetosphere varies in size, depending on the solar wind.

20. Van Allen Belts, named after James Van Allen of the Univ. of Iowa, who sent instruments up on early U.S. spacecraft. link link

21. The Aurora Borealis are due to charged particles trapped in the Earth’s magnetic field, causing air molecules to glow.