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  2. Light-year - Wikipedia

    en.wikipedia.org/wiki/Light-year

    A light-year, alternatively spelled light year (ly or lyr [3]), is a unit of length used to express astronomical distances and is equal to exactly 9 460 730 472 580.8 km, which is approximately 5.88 trillion mi.

  3. Astronomical unit - Wikipedia

    en.wikipedia.org/wiki/Astronomical_unit

    Light-day: 173 — Distance light travels in one day — 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 ...

  4. Speed of light - Wikipedia

    en.wikipedia.org/wiki/Speed_of_Light

    A light-year is the distance light travels in one Julian year, around 9461 billion kilometres, 5879 billion miles, or 0.3066 parsecs. In round figures, a light year is nearly 10 trillion kilometres or nearly 6 trillion miles. Proxima Centauri, the closest star to Earth after the Sun, is around 4.2 light-years away. [89]

  5. Solar radius - Wikipedia

    en.wikipedia.org/wiki/Solar_radius

    The result was a measured radius of 696,342 ± 65 kilometres (432,687 ± 40 miles). [4] Haberreiter, Schmutz & Kosovichev (2008) [1] determined the radius corresponding to the solar photosphere to be 695,660 ± 140 kilometres (432,263 ± 87 miles). This new value is consistent with helioseismic estimates; the same study showed that previous ...

  6. List of unusual units of measurement - Wikipedia

    en.wikipedia.org/wiki/List_of_unusual_units_of...

    Lunar distance (LD), the distance from the centre of Earth to the centre of the Moon, is a unit of measure in astronomy. The lunar distance is approximately 384,400 km (238,900 mi), or 1.28 light-seconds; this is roughly 30 times Earth's diameter. A little less than 400 lunar distances make up an astronomical unit.

  7. Hubble's law - Wikipedia

    en.wikipedia.org/wiki/Hubble's_law

    The Hubble length or Hubble distance is a unit of distance in cosmology, defined as cH −1 — the speed of light multiplied by the Hubble time. It is equivalent to 4,420 million parsecs or 14.4 billion light years. (The numerical value of the Hubble length in light years is, by definition, equal to that of the Hubble time in years.)

  8. Cosmic distance ladder - Wikipedia

    en.wikipedia.org/wiki/Cosmic_distance_ladder

    The amount of shift is quite small, even for the nearest stars, measuring 1 arcsecond for an object at 1 parsec's distance (3.26 light-years), and thereafter decreasing in angular amount as the distance increases. Astronomers usually express distances in units of parsecs (parallax arcseconds); light-years are used in popular media.

  9. Orders of magnitude (length) - Wikipedia

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

    3.1 Em – 310 light-yearsdistance to Canopus according to Hipparcos [202] 3.9 Em – 410 light-yearsdistance to Betelgeuse according to Hipparcos [203] 6.2 Em – 650 light-yearsdistance to the Helix Nebula, located in the constellation Aquarius [204] 8.2 Em – 860 light-yearsdistance to Rigel according to Hipparcos [202]