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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. Light-year - Wikipedia

    en.wikipedia.org/wiki/Light-year

    The largest unit for expressing distances across space at that time was the astronomical unit, equal to the radius of the Earth's orbit at 150 million kilometres (93 million miles). In those terms, trigonometric calculations based on 61 Cygni's parallax of 0.314 arcseconds, showed the distance to the star to be 660 000 astronomical units (9.9 ...

  4. Astronomical unit - Wikipedia

    en.wikipedia.org/wiki/Astronomical_unit

    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 astronomical unit, is used to measure distances beyond the scope of the Solar ...

  5. Speed of light - Wikipedia

    en.wikipedia.org/wiki/Speed_of_Light

    For example, in imperial units, the speed of light is approximately 186 282 miles per second, [Note 4] or roughly 1 foot per nanosecond. [Note 5] [15] [16] In branches of physics in which c appears often, such as in relativity, it is common to use systems of natural units of measurement or the geometrized unit system where c = 1.

  6. Orders of magnitude (length) - Wikipedia

    en.wikipedia.org/wiki/Orders_of_magnitude_(length)

    100 μm – smallest distance that can be seen with the naked eye; 100 μm – average diameter of a strand of human hair [25] 100 μm – thickness of a coat of paint; 100 μm – length of a dust particle; 120 μm – the geometric mean of the Planck length and the diameter of the observable universe: √ 8.8 × 10 26 m × 1.6 × 10 −35 m

  7. Speed of gravity - Wikipedia

    en.wikipedia.org/wiki/Speed_of_gravity

    miles per second: 186 000: miles per hour [1] 671 000 000: astronomical units per day: 173 [Note 1] parsecs per year: 0.307 [Note 2] Approximate light signal travel times; Distance: Time: one foot: 1.0 ns: one metre: 3.3 ns: from geostationary orbit to Earth: 119 ms: the length of Earth's equator: 134 ms: from Moon to Earth: 1.3 s: from Sun to ...

  8. Action at a distance - Wikipedia

    en.wikipedia.org/wiki/Action_at_a_distance

    Action at a distance is the concept in physics that an object's motion can be affected by another object without the two being in physical contact; that is, it is the concept of the non-local interaction of objects that are separated in space.

  9. Escape velocity - Wikipedia

    en.wikipedia.org/wiki/Escape_velocity

    Escape speed at a distance d from the center of a spherically symmetric primary body (such as a star or a planet) with mass M is given by the formula [2] [3] = = where: G is the universal gravitational constant (G ≈ 6.67 × 10 −11 m 3 ⋅kg −1 ⋅s −2 ‍ [4])