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  2. Horizon - Wikipedia

    en.wikipedia.org/wiki/Horizon

    To compute the greatest distance D BL at which an observer B can see the top of an object L above the horizon, simply add the distances to the horizon from each of the two points: D BL = D B + D L For example, for an observer B with a height of h B =1.70 m standing on the ground, the horizon is D B =4.65 km away.

  3. Line-of-sight propagation - Wikipedia

    en.wikipedia.org/wiki/Line-of-sight_propagation

    Line-of-sight propagation is a characteristic of electromagnetic radiation or acoustic wave propagation which means waves can only travel in a direct visual path from the source to the receiver without obstacles. [1] Electromagnetic transmission includes light emissions traveling in a straight line.

  4. Line of sight - Wikipedia

    en.wikipedia.org/wiki/Line_of_sight

    The subject may be any definable object taken note of or to be taken note of by the observer, at any distance more than least distance of distinct vision. In optics, refraction of a ray due to use of lenses can cause distortion. [2] Shadows, patterns and movement can also influence line of sight interpretation [3] [4] (as in optical illusions).

  5. List of the most distant astronomical objects - Wikipedia

    en.wikipedia.org/wiki/List_of_the_most_distant...

    This article documents the most distant astronomical objects discovered and verified so far, and the time periods in which they were so classified. For comparisons with the light travel distance of the astronomical objects listed below, the age of the universe since the Big Bang is currently estimated as 13.787±0.020 Gyr. [1]

  6. Mysterious light show over Martin City remains unexplained - AOL

    www.aol.com/mysterious-light-show-over-martin...

    Nov. 12—When O'Brien Byrd woke up to a strange light coming through his bedroom window in Martin City early Wednesday morning, he knew something odd was going on. It was about 4:30 a.m. when the ...

  7. Visibility - Wikipedia

    en.wikipedia.org/wiki/Visibility

    Because the object is assumed to be perfectly black, it must absorb all of the light incident on it. Thus when x=0 (at the object), F(0) = 0 and C V (0) = 1. Between the object and the observer, F(x) is affected by additional light that is scattered into the observer's line of sight and the absorption of light by gases and particles.

  8. Your Grow Light Is Probably Too Far from Your Plants ... - AOL

    www.aol.com/lifestyle/grow-light-probably-too...

    Houseplants can sometimes be 2-4 feet away, allowing you to group several plants under one light source. Of course, higher-powered LED fixtures can be farther away than low-powered lights.

  9. Observable universe - Wikipedia

    en.wikipedia.org/wiki/Observable_universe

    The observable universe is a spherical region of the universe consisting of all matter that can be observed from Earth or its space-based telescopes and exploratory probes at the present time; the electromagnetic radiation from these objects has had time to reach the Solar System and Earth since the beginning of the cosmological expansion.