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  2. Light-year - Wikipedia

    en.wikipedia.org/wiki/Light-year

    The product of Simon Newcomb's J1900.0 mean tropical year of 31 556 925.9747 ephemeris seconds and a speed of light of 299 792.5 km/s produced a light-year of 9.460 530 × 10 15 m (rounded to the seven significant digits in the speed of light) found in several modern sources [10] [11] [12] was probably derived from an old source such as C. W ...

  3. Astronomical unit - Wikipedia

    en.wikipedia.org/wiki/Astronomical_unit

    Light-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 astronomical unit, is used to measure distances beyond the ...

  4. Unit of length - Wikipedia

    en.wikipedia.org/wiki/Unit_of_length

    The basic unit of length in the imperial and U.S. customary systems is the yard, defined as exactly 0.9144 m by international treaty in 1959. [2] [5] Common imperial units and U.S. customary units of length include: [6] thou or mil (1 ⁄ 1000 of an inch) inch (25.4 mm) foot (12 inches, 0.3048 m) yard (3 feet, 0.9144 m)

  5. Light-second - Wikipedia

    en.wikipedia.org/wiki/Light-second

    Example Meters Kilometers Miles light-second 1 light-second 299 792 458 m: 2.998 × 10 5 km: 1.863 × 10 5 miles: Average distance from the Earth to the Moon is about 1.282 light-seconds light-minute 60 light-seconds = 1 light-minute 17 987 547 480 m: 1.799 × 10 7 km: 1.118 × 10 7 miles: Average distance from the Earth to the Sun is 8.317 ...

  6. Distance measure - Wikipedia

    en.wikipedia.org/wiki/Distance_measure

    Distance measures are used in physical cosmology to give a natural notion of the distance between two objects or events in the universe.They are often used to tie some observable quantity (such as the luminosity of a distant quasar, the redshift of a distant galaxy, or the angular size of the acoustic peaks in the cosmic microwave background (CMB) power spectrum) to another quantity that is ...

  7. Proper motion - Wikipedia

    en.wikipedia.org/wiki/Proper_motion

    A proper motion of 1 arcsec per year 1 light-year away corresponds to a relative transverse speed of 1.45 km/s. Barnard's Star's transverse speed is 90 km/s and its radial velocity is 111 km/s (perpendicular (at a right, 90° angle), which gives a true or "space" motion of 142 km/s.

  8. Cosmic distance ladder - Wikipedia

    en.wikipedia.org/wiki/Cosmic_distance_ladder

    The apparent magnitude, the magnitude as seen by the observer (an instrument called a bolometer is used), can be measured and used with the absolute magnitude to calculate the distance d to the object in parsecs [14] as follows: ⁡ = + or = (+) / where m is the apparent magnitude, and M the absolute magnitude. For this to be accurate, both ...

  9. Parsec - Wikipedia

    en.wikipedia.org/wiki/Parsec

    where θ is the measured angle in arcseconds, Distance earth-sun is a constant (1 au or 1.5813 × 10 −5 ly). The calculated stellar distance will be in the same measurement unit as used in Distance earth-sun (e.g. if Distance earth-sun = 1 au , unit for Distance star is in astronomical units; if Distance earth-sun = 1.5813 × 10 −5 ly, unit ...