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lesson 4 - Earth-Sun Geometry Of all the spatial...

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Earth-Sun Geometry Of all the spatial relationships that geographers study, the relationship between the Earth and Sun has the biggest impact upon our daily lives. The Earth is powered to a large extent by the energy that it receives from the Sun. This energy comes in the form of solar radiation, which drives most of the processes that occur on Earth, including the weather systems that ultimately determine global climate. It is, therefore, necessary to have a basic understanding of this relationship. Image of the Sun's surface. Image source: "Large prominence June 9, 2002" from Space Environment Center Gallery of Solar Activity , SWPC-NOAA, U.S. [2008] The Earth in space The universe is made up of millions of galaxies and each galaxy is home to billions of stars. One of these stars is our Sun, located in the Milky Way Galaxy. The Sun is the center of our solar system, which consists of eight planets orbiting the Sun. (Note: Pluto, the one-time ninth planet, was officially stripped of its title in 2006.) Within our solar system, Earth is the third planet from the Sun (just far enough away from the Sun that we do not burn up, but not so far away that we freeze).
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The solar system. Image source: The Solar System , NASA's Planetary PhotoJournal [September 1999] The Earth is not a perfectly round sphere as it appears below in the left image. It bulges slightly at the equator and is flattened somewhat at the poles making it an oblate spheroid ( see right image below). Additionally, relief (mountains and canyons) gives the Earth an irregular undulating surface. Thus, the Earth is officially a geoid . The circumference of the Earth measured at the equator is 40,075 km (24,902 mi), while the polar circumference is only 40,008 km (24,860 mi). The bulge at the equator, which gives the planet a slightly thicker middle, is caused by the spinning of the Earth on its axis. Image source: Earth appears as a sphere, NASA [September 1998]; Earth as an oblate spheroid, NASA [September 1998]. Modified by Cathryn M. Dowd, Michigan State University, 2001.
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The following are activities/sites that go Above And Beyond the mandatory course material: - " Gravity Anomaly Maps and The Geoid " (EO-NASA) - " What is the geoid? " (NGS-NOAA)
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Seasons To understand how the tilt causes the seasons we experience on Earth, first imagine what would happen if the Earth was not tilted. Under these circumstances, the plane of ecliptic would run right through the equator. As a result, the Sun would always be directly overhead at the equator and lower latitudes (near the equator) would receive even more intense solar radiation than today (imagine a beam of light striking at the same place on a surface constantly). Higher latitudes (nearer the poles) would receive even less intense radiation than today because the Sun's rays would hit the Earth's surface at an angle less than 90 degrees (a more oblique angle) due to the curvature of the Earth's surface. If this were the case, all places on Earth would receive a constant amount of solar radiation all year
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lesson 4 - Earth-Sun Geometry Of all the spatial...

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