GEOG101: Physical Geography
Lecture 04: Monday, January 26, 2009
Topics
1. The Solar System, Sun, and Earth
2. Solar Energy: From Sun to Earth
3. The Seasons
Copyrights of Pearson-Prentice, demonstrated for educational purposes in limited time period
The Solar System, Sun, and Earth
• Dimensions and Distances (speed of light):
The speed of light: 300,000 km/second;
A light year = 9.5 trillion km (a long distance);
Milky Way Galaxy 100,000 ly across;
Our Solar System 11 light-hours across;
Moon is 1.28 light-seconds away;
Average distance from Earth to the Sun is 150,000,000 km (93,000,000 mi).
• Perihelion - closest at January 3: 147,255,000 km (91,500,000 mi);
• Aphelion - farthest at July 4: 152,083,000 km (94,500,000 mi);
• Plane of the ecliptic - the Plane of Earth's orbit;
• Origins of the Universe, Solar System and the Earth:
Theory of the Big Bang;
Age of Universe about 20 Billion years;
Age of earth about 4.5 to 4.6 Billion years;
Planetesimal hypothesis for the solar system;
Components of the solar system (apparently) all formed in a short time frame about 4.5 to 4.6 billion years ago;
Solar Energy: From Sun to Earth
• The source of solar energy: Fusion:
Why fusion produces energy?
Under what conditions would fusion occur?
What drives the sun to have the fusion?
•Solar Activity and Solar Wind
What is the solar wind ?
What is the sunspots
What frequency does a sunspot cycle commonly have ?
• Understand the following terms:
Aurora Borealis & Aurora Australis;
Magnetosphere;
Wavelength and Frequency;
Insolation;
Subsolar point.
• Understand the Electromagnetic Spectrums of the Earth's energy budget (input and output).
The Seasons
• Understand the reasons for seasonal changes;
• If the Earth's axis is not tilted, there would be no seasonal changes. WHY?
• Read carefully Figure 2.15, Page 54, make sure you understand this diagram and can have a march of the seasonal changes illustrated in this diagram.
• Understand the following terms:
Revolution and Rotation of the Earth;
Axial parallelism;
Winter solstice;
Spring equinox;
Summer solstice;
Fall equinox