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  2. Rare Earth hypothesis - Wikipedia

    en.wikipedia.org/wiki/Rare_Earth_hypothesis

    The Rare Earth hypothesis argues that planets with complex life, like Earth, are exceptionally rare.. In planetary astronomy and astrobiology, the Rare Earth hypothesis argues that the origin of life and the evolution of biological complexity, such as sexually reproducing, multicellular organisms on Earth, and subsequently human intelligence, required an improbable combination of astrophysical ...

  3. Rare Earth: Why Complex Life Is Uncommon in the Universe

    en.wikipedia.org/wiki/Rare_Earth:_Why_Complex...

    Rare Earth was succeeded in 2003 by the follow-on book The Life and Death of Planet Earth: How the New Science of Astrobiology Charts the Ultimate Fate of our World, also by Ward and Brownlee, which talks about the Earth's long-term future and eventual demise under a warming and expanding Sun, showing readers the concept that planets like Earth ...

  4. Earth - Wikipedia

    en.wikipedia.org/wiki/Earth

    Earth's average orbital distance is about 150 million km (93 million mi), which is the basis for the astronomical unit (AU) and is equal to roughly 8.3 light minutes or 380 times Earth's distance to the Moon. Earth orbits the Sun every 365.2564 mean solar days, or one sidereal year. With an apparent movement of the Sun in Earth's sky at a rate ...

  5. Gaia hypothesis - Wikipedia

    en.wikipedia.org/wiki/Gaia_hypothesis

    The mythical Gaia was the primal Greek goddess personifying the Earth, the Greek version of "Mother Nature" (from Ge = Earth, and Aia = PIE grandmother), or the Earth Mother. James Lovelock gave this name to his hypothesis after a suggestion from the novelist William Golding , who was living in the same village as Lovelock at the time ...

  6. Plate tectonics - Wikipedia

    en.wikipedia.org/wiki/Plate_tectonics

    Plate tectonics (from Latin tectonicus, from Ancient Greek τεκτονικός (tektonikós) 'pertaining to building') [1] is the scientific theory that the Earth's lithosphere comprises a number of large tectonic plates, which have been slowly moving since 3–4 billion years ago.

  7. Rare-earth element - Wikipedia

    en.wikipedia.org/wiki/Rare-earth_element

    The principal sources of rare-earth elements are the minerals bastnäsite (RCO 3 F, where R is a mixture of rare-earth elements), monazite (XPO 4, where X is a mixture of rare-earth elements and sometimes thorium), and loparite ((Ce,Na,Ca)(Ti,Nb)O 3), and the lateritic ion-adsorption clays.

  8. American exceptionalism - Wikipedia

    en.wikipedia.org/wiki/American_exceptionalism

    American exceptionalism is the belief that the United States is either distinctive, unique, or exemplary compared to other nations. [1] Proponents argue that the values , political system , and historical development of the U.S. are unique in human history , often with the implication that it is both destined and entitled to play a distinct and ...

  9. Five themes of geography - Wikipedia

    en.wikipedia.org/wiki/Five_themes_of_geography

    Map projections are used to represent the three-dimensional Earth on a two-dimensional map. The Earth's position relative to the Sun affects climate , seasons , and time zones . [ 1 ] Location as a theme helps teachers to demonstrate to students that observers have to know and be able to explain where something is before it can be examined ...