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  2. Timeline of first images of Earth from space - Wikipedia

    en.wikipedia.org/wiki/Timeline_of_first_images...

    First full-disk black-and-white filtered [40] color picture of the Earth. [6] November 10, 1967 ATS-3: First full-disk "true color" [41] picture of the Earth; [42] subsequently used on the cover of the first Whole Earth Catalog. [43] [42] December 21, 1968 Apollo 8: First full-disk image of Earth from space taken by a person, probably by ...

  3. Chronology of the universe - Wikipedia

    en.wikipedia.org/wiki/Chronology_of_the_universe

    At the end of this epoch, the spherical volume of space which will become the observable universe is about 300 light-years in radius, baryonic matter density is on the order of 4 grams per m 3 (about 0.3% of sea level air density)—however, most energy at this time is in electromagnetic radiation. Photon epoch: 10 s ~ 370 ka: 10 9 K ~ 4000 K

  4. Purple Earth hypothesis - Wikipedia

    en.wikipedia.org/wiki/Purple_Earth_hypothesis

    The Purple Earth Hypothesis (PEH) is an astrobiological hypothesis, first proposed by molecular biologist Shiladitya DasSarma in 2007, [1] that the earliest photosynthetic life forms of Early Earth were based on the simpler molecule retinal rather than the more complex porphyrin-based chlorophyll, making the surface biosphere appear purplish ...

  5. Aether theories - Wikipedia

    en.wikipedia.org/wiki/Aether_theories

    Isaac Newton suggests the existence of an aether in the Third Book of Opticks (1st ed. 1704; 2nd ed. 1718): "Doth not this aethereal medium in passing out of water, glass, crystal, and other compact and dense bodies in empty spaces, grow denser and denser by degrees, and by that means refract the rays of light not in a point, but by bending them gradually in curve lines? ...

  6. Pale Blue Dot (book) - Wikipedia

    en.wikipedia.org/wiki/Pale_Blue_Dot_(book)

    The first part of the book examines the claims made throughout history that Earth and the human species are unique. Sagan proposes two reasons for the persistence of the idea of a geocentric, or Earth-centered universe: human pride in our existence, and the threat of torturing those who dissented from it, particularly during the time of the Roman Inquisition.

  7. Aether (classical element) - Wikipedia

    en.wikipedia.org/wiki/Aether_(classical_element)

    According to ancient and medieval science, aether (/ ˈ iː θ ər /, alternative spellings include æther, aither, and ether), also known as the fifth element or quintessence, is the material that fills the region of the universe beyond the terrestrial sphere. [1]

  8. AOL Mail

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    Get AOL Mail for FREE! Manage your email like never before with travel, photo & document views. Personalize your inbox with themes & tabs. You've Got Mail!

  9. History of Earth - Wikipedia

    en.wikipedia.org/wiki/History_of_Earth

    The first eon in Earth's history, the Hadean, begins with the Earth's formation and is followed by the Archean eon at 3.8 Ga. [2]: 145 The oldest rocks found on Earth date to about 4.0 Ga, and the oldest detrital zircon crystals in rocks to about 4.4 Ga, [34] [35] [36] soon after the formation of the Earth's crust and the Earth