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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 9.46 trillion km or 5.88 trillion mi.

  3. Astronomical unit - Wikipedia

    en.wikipedia.org/wiki/Astronomical_unit

    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 astronomical unit, is ...

  4. List of nearest stars - Wikipedia

    en.wikipedia.org/wiki/List_of_nearest_stars

    This number is likely much higher, due to the sheer number of stars needed to be surveyed; a star approaching the Solar System 10 million years ago, moving at a typical Sun-relative 20–200 kilometers per second, would be 600–6,000 light-years from the Sun at present day, with millions of stars closer to the Sun.

  5. List of the most distant astronomical objects - Wikipedia

    en.wikipedia.org/wiki/List_of_the_most_distant...

    For comparisons with the light travel distance of the astronomical objects listed below, the age of the universe since the Big Bang is currently estimated as 13.787±0.020 Gyr. [1] Distances to remote objects, other than those in nearby galaxies, are nearly always inferred by measuring the cosmological redshift of their light. By their nature ...

  6. Wikipedia talk : Manual of Style/Dates and numbers/Archive 163

    en.wikipedia.org/wiki/Wikipedia_talk:Manual_of...

    "Light year" converted to km, in exponential notation. "34.5 million light years (3.26 × 10 23 km) " - User 1 "Light years" converted to "kilometers" then "parsecs", in words, but no higher than trillion. "34.5 million light years (326 billion trillion kilometers ; 10.6 billion parsecs ) plus or minus .3 million light years."

  7. 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. [90]

  8. Orders of magnitude (length) - Wikipedia

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

    To help compare different distances this section lists lengths starting at 10 15 m (1 Pm or 1 trillion km or 6685 astronomical units (AU) or 0.11 light-years). 1.0 Pm = 0.105702341 light-years 1.9 Pm ± 0.5 Pm = 12,000 AU = 0.2 light-year radius of Cat's Eye Nebula 's inner core [ 194 ] [ 195 ]

  9. Solar radius - Wikipedia

    en.wikipedia.org/wiki/Solar_radius

    light-year: 2.254 61 ... B3 defined the nominal solar radius (symbol ) to be equal to exactly 695 700 km. [5] The nominal value, which is the rounded value ...