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  2. Observable universe - Wikipedia

    en.wikipedia.org/wiki/Observable_universe

    So if the matter that originally emitted the oldest CMBR photons has a present distance of 46 billion light-years, then the distance would have been only about 42 million light-years at the time of decoupling. The light-travel distance to the edge of the observable universe is the age of the universe times the speed of light, 13.8 billion light ...

  3. Observational astronomy - Wikipedia

    en.wikipedia.org/wiki/Observational_astronomy

    The human eye discards what it sees from split-second to split-second, but photographic film gathers more and more light for as long as the shutter is open. The resulting image is permanent, so many astronomers can use the same data. It is possible to see objects as they change over time (SN 1987A is a spectacular example).

  4. Light-year - Wikipedia

    en.wikipedia.org/wiki/Light-year

    The light-month, roughly one-twelfth of a light-year, is also used occasionally for approximate measures. [37] [38] The Hayden Planetarium specifies the light month more precisely as 30 days of light travel time. [39] Light travels approximately one foot in a nanosecond; the term "light-foot" is sometimes used as an informal measure of time. [40]

  5. Infrared Array Camera - Wikipedia

    en.wikipedia.org/wiki/Infrared_Array_Camera

    Infrared observations can see objects hidden in visible light, such as HUDF-JD2 shown. This shows how the Spitzer IRAC camera was able see beyond the wavelengths of Hubble's instruments Four-band IRAC image of the Trifid Nebula. The wavelengths the camera sees are mapped to the visible spectrum for a false color image that

  6. Eidetic memory - Wikipedia

    en.wikipedia.org/wiki/Eidetic_memory

    Eidetic memory (/ aɪ ˈ d ɛ t ɪ k / eye-DET-ik), also known as photographic memory and total recall, is the ability to recall an image from memory with high precision—at least for a brief period of timeafter seeing it only once [1] and without using a mnemonic device.

  7. Visual perception - Wikipedia

    en.wikipedia.org/wiki/Visual_perception

    [9] [10] He was the first person to explain that vision occurs when light bounces on an object and then is directed to one's eyes. [11] Leonardo da Vinci (1452–1519) is believed to be the first to recognize the special optical qualities of the eye. He wrote "The function of the human eye ... was described by a large number of authors in a ...

  8. Visible-light astronomy - Wikipedia

    en.wikipedia.org/wiki/Visible-light_astronomy

    Visible-light astronomy has existed as long as people have been looking up at the night sky, although it has since improved in its observational capabilities since the invention of the telescope, which is commonly credited to Hans Lippershey, a German-Dutch spectacle-maker, [1] although Galileo played a large role in the development and ...

  9. Emission theory (vision) - Wikipedia

    en.wikipedia.org/wiki/Emission_theory_(vision)

    Alhazen was the first person to explain that vision occurs when light reflects from an object into one's eyes. [ 7 ] The rise of rationalist physics in the 17th century led to a novel version of the intromissionist theory that proved extremely influential and displaced any legacies of the old emissive theories.