Earth Science: Geology, the Environment, and the Universe

Chapter 14: Climate

Problem of the Week

Life: What’s Eccentricity Got To Do With It?

Scientists speculate that the nearly circular orbit of Earth provides a more constant, stable influx of solar energy, and therefore, a more stable global climate. Planets with more elliptical orbits may have more extreme or variable climates depending on the degree of eccentricity. Due to the difficulty in detecting the small gravitational effects, many of these planets are larger than Jupiter. Some scientists are confident that smaller planets exist and that their orbits may not be as elliptical as the currently known extra-solar planets.

Students should infer that the more circular an orbit, the more constant the influx of solar radiation resulting in a fairly stable global climate. Distance from the star is also a factor. Look at Venus for example. This planet has the most eccentric orbit, and it does have a fairly stable planetary climate. However, it is a severe climate–one not conducive to life as we know it. Students should infer that distance is another factor.

Resources:

  1. Gale Group (2000).
    Elliptical orbits may be planetary norm. Science News. Dec 11, 1999.

  2. Orbits of other distant planets oval - not circular, January 9, 1999.
    Public Affairs Office at San Francisco State University, Diag Center.

  3. Glennda Chui (2000).
    Small Worlds, After All. Mercury News.
    *A general description of how scientists infer that a planet exists.

  4. Space Link: Charting the Planets.
    Education Division. NASA.

  5. Interactive Investigation Of The Shapes Of Planetary Orbits.
    * Contains a great activity for investigating orbital eccentricity.

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