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From Karnataka Open Educational Resources
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, 17:51, 2 October 2012
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| === The Law of Orbits === | | === The Law of Orbits === |
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− | All planets move in elliptical orbits, with the sun at one focus. An ellipse is a closed curve such that the sum of the distances from any point P on the curve to two fixed points (called the foci, F1 and F2) remains constant. <br> | + | All planets move in elliptical orbits, with the sun at one focus. An ellipse is a closed curve such that the sum of the distances from any point P on the curve to two fixed points (called the foci, F1 and F2) remains constant. <br><br> |
| '''Orbit eccentricity''' | | '''Orbit eccentricity''' |
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| The semi major axis of the ellipse is a and represents the planet's average distance from the Sun. The eccentricity, “e” is defined so that “ea” is the distance from the centre to either focus. A circle is a special case of an ellipse where the two foci coincide. The Earth and most of the other planets have nearly circular orbits. For Earth, “e” = 0.017.<br><br> | | The semi major axis of the ellipse is a and represents the planet's average distance from the Sun. The eccentricity, “e” is defined so that “ea” is the distance from the centre to either focus. A circle is a special case of an ellipse where the two foci coincide. The Earth and most of the other planets have nearly circular orbits. For Earth, “e” = 0.017.<br><br> |
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| + | [[Image:Gravitation%20for%20wiki_html_m75870f64.gif]] <br> |
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| === The Law of Equal Areas === | | === The Law of Equal Areas === |
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