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  2. Light-second - Wikipedia

    en.wikipedia.org/wiki/Light-second

    The light-second is a unit of length useful in astronomy, telecommunications and relativistic physics.It is defined as the distance that light travels in free space in one second, and is equal to exactly 299 792 458 m (approximately 983 571 055 ft or 186 282 miles).

  3. Speed of light - Wikipedia

    en.wikipedia.org/wiki/Speed_of_Light

    The speed of light in vacuum, commonly denoted c, is a universal physical constant that is exactly equal to 299,792,458 metres per second (approximately 300,000 kilometres per second; 186,000 miles per second; 671 million miles per hour).

  4. Astronomical unit - Wikipedia

    en.wikipedia.org/wiki/Astronomical_unit

    Light-day: 173 — Distance light travels in one dayLight-year: 63 241 — Distance light travels in one Julian year (365.25 days) — Oort cloud: 75 000: ± 25 000: Distance of the outer limit of Oort cloud from the Sun (estimated, corresponds to 1.2 light-years) — Parsec: 206 265 — One parsec. The parsec is defined in terms of the ...

  5. Unit of time - Wikipedia

    en.wikipedia.org/wiki/Unit_of_time

    The amount of time light takes to travel one Planck length. quectosecond: 10 −30 s: One nonillionth of a second. rontosecond: 10 −27 s: One octillionth of a second. yoctosecond: 10 −24 s: One septillionth of a second. jiffy (physics) 3 × 10 −24 s: The amount of time light takes to travel one fermi (about the size of a nucleon) in a ...

  6. Fizeau's measurement of the speed of light in air - Wikipedia

    en.wikipedia.org/wiki/Fizeau's_measurement_of_the...

    Figure 1: Schematic of the Fizeau apparatus. The light passes on one side of a tooth on the way out, and the other side on the way back, assuming the cog rotates one tooth during transit of the light. [1]: 123 In 1848–49, Hippolyte Fizeau determined the speed of light using an intense light source at the bell tower of his father's holiday ...

  7. Parsec - Wikipedia

    en.wikipedia.org/wiki/Parsec

    [a] The parsec unit is obtained by the use of parallax and trigonometry, and is defined as the distance at which 1 AU subtends an angle of one arcsecond [1] (⁠ 1 / 3600 ⁠ of a degree). The nearest star, Proxima Centauri , is about 1.3 parsecs (4.2 light-years) from the Sun : from that distance, the gap between the Earth and the Sun spans ...

  8. How long does it take the average person to run a marathon ...

    www.aol.com/news/long-does-average-runner...

    For example, if you run a mile in seven minutes and 30 seconds, then the full 26.2 miles should take around 3:16:38, explains David Herzberg, a physical therapist and owner of Launch Physical ...

  9. Astronomical system of units - Wikipedia

    en.wikipedia.org/wiki/Astronomical_system_of_units

    The speed of light in IAU is the defined value c 0 = 299 792 458 m/s of the SI units. In terms of this speed, the old definition of the astronomical unit of length had the accepted value: [ 3 ] 1 au = c 0 τ A = ( 149 597 870 700 ± 3 ) m, where τ A is the transit time of light across the astronomical unit.