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  2. Parsec - Wikipedia

    en.wikipedia.org/wiki/Parsec

    The use of the parsec as a unit of distance follows naturally from Bessel's method, because the distance in parsecs can be computed simply as the reciprocal of the parallax angle in arcseconds (i.e.: if the parallax angle is 1 arcsecond, the object is 1 pc from the Sun; if the parallax angle is 0.5 arcseconds, the object is 2 pc away; etc.).

  3. Astronomical unit - Wikipedia

    en.wikipedia.org/wiki/Astronomical_unit

    Average distance from the Sun — Earth: 1.00 — Average distance of Earth's orbit from the Sun (sunlight travels for 8 minutes and 19 seconds before reaching Earth) — Mars: 1.52 — Average distance from the Sun — Jupiter: 5.2 — Average distance from the Sun — Light-hour: 7.2 — Distance light travels in one hour — Saturn: 9.5 ...

  4. 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 ...

  5. Parallax in astronomy - Wikipedia

    en.wikipedia.org/wiki/Parallax_in_astronomy

    A parsec is the distance from the Sun to an astronomical object that has a parallax angle of one arcsecond (not to scale). The parsec (symbol: pc) is a unit of length used to measure the large distances to astronomical objects outside the Solar System, approximately equal to 3.26 light-years or 206,265 astronomical units (AU), i.e. 30.9 trillion kilometres (19.2 trillion miles).

  6. Orders of magnitude (length) - Wikipedia

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

    Distance traveled by light in vacuum in one year; at its current speed, Voyager 1 would need 17,500 years to travel this distance 10 16: 10 Pm: 30.857 Pm 1 parsec: 39.9 Pm Distance to nearest star (Proxima Centauri) 41.3 Pm As of March 2013, distance to nearest discovered extrasolar planet (Alpha Centauri Bc) 10 17: 100 Pm: 193 Pm

  7. List of nearest stars - Wikipedia

    en.wikipedia.org/wiki/List_of_nearest_stars

    The position marks are entered inward from the distance marks according to their declinations, connected by lines (doted when positive) representing the arcs of the declinations viewed edge-on. This list covers all known stars, white dwarfs, brown dwarfs, and sub-brown dwarfs within 20 light-years (6.13 parsecs) of the Sun. So far, 131 such ...

  8. Cosmic distance ladder - Wikipedia

    en.wikipedia.org/wiki/Cosmic_distance_ladder

    The cosmic distance ladder (also known as the extragalactic distance scale) is the succession of methods by which astronomers determine the distances to celestial objects. A direct distance measurement of an astronomical object is possible only for those objects that are "close enough" (within about a thousand parsecs) to Earth. The techniques ...

  9. List of nearest galaxies - Wikipedia

    en.wikipedia.org/wiki/List_of_nearest_galaxies

    This is a list of known galaxies within 3.8 megaparsecs (12.4 million light-years) of the Solar System, in ascending order of heliocentric distance, or the distance to the Sun. This encompasses about 50 major Local Group galaxies, and some that are members of neighboring galaxy groups , the M81 Group and the Centaurus A/M83 Group , and some ...