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  2. Light-year - Wikipedia

    en.wikipedia.org/wiki/Light-year

    The centre of the Milky Way is about 26 000 light-years away. [35] [36] 1 × 10 5 ly: The Milky Way is about 100 000 light-years across. 1.65 × 10 5 ly: R136a1, in the Large Magellanic Cloud, the most luminous star known at 8.7 million times the luminosity of the Sun, has an apparent magnitude 12.77, just brighter than 3C 273. 10 6: 2.5 × 10 6 ly

  3. 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]

  4. 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 ...

  5. 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.

  6. Interstellar travel - Wikipedia

    en.wikipedia.org/wiki/Interstellar_travel

    Light in a vacuum travels around 300,000 kilometres (186,000 mi) per second, so 1 light-year is about 9.461 × 10 12 kilometers (5.879 trillion miles) or 63,241 AU. Hence, Proxima Centauri is approximately 4.243 light-years from Earth.

  7. A Mysterious Light Has Been Blinking in Space Every 21 ... - AOL

    www.aol.com/lifestyle/mysterious-light-blinking...

    A mysterious light has been blinking in space every 21 minutes for 35 years–and scientists have no idea what it is. What could it be?

  8. Galactic year - Wikipedia

    en.wikipedia.org/wiki/Galactic_year

    One galactic year is approximately 225 million Earth years. [2] The Solar System is traveling at an average speed of 230 km/s (828,000 km/h) or 143 mi/s (514,000 mph) within its trajectory around the Galactic Center, [ 3 ] a speed at which an object could circumnavigate the Earth's equator in 2 minutes and 54 seconds; that speed corresponds to ...

  9. Astronomical system of units - Wikipedia

    en.wikipedia.org/wiki/Astronomical_system_of_units

    The speed of light in IAU is the defined value c 0 = 299 792 458 m/s of the SI units. In terms of this speed, the old definition of the astronomical unit of length had the accepted value: [ 3 ] 1 au = c 0 τ A = ( 149 597 870 700 ± 3 ) m, where τ A is the transit time of light across the astronomical unit.