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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 (Scientific notation: 9.4607304725808 × 10 12 km), which is approximately 5.88 trillion mi.

  3. Earth's orbit - Wikipedia

    en.wikipedia.org/wiki/Earth's_orbit

    Earth orbit (yellow) compared to a circle (gray) Earth orbits the Sun at an average distance of 149.60 million km (92.96 million mi), or 8.317 light-minutes, [1] in a counterclockwise direction as viewed from above the Northern Hemisphere. One complete orbit takes 365.256 days (1 sidereal year), during which time Earth has traveled 940 million ...

  4. List of nearest stars - Wikipedia

    en.wikipedia.org/wiki/List_of_nearest_stars

    The closest encounter to the Sun so far predicted is the low-mass orange dwarf star Gliese 710 / HIP 89825 with roughly 60% the mass of the Sun. [4] It is currently predicted to pass 0.1696 ± 0.0065 ly (10 635 ± 500 au) from the Sun in 1.290 ± 0.04 million years from the present, close enough to significantly disturb the Solar System's Oort ...

  5. 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 ...

  6. Solar radius - Wikipedia

    en.wikipedia.org/wiki/Solar_radius

    The solar radius is usually defined as the radius to the layer in the Sun 's photosphere where the optical depth equals 2/3: [1] 695,700 kilometres (432,300 miles) is approximately 10 times the average radius of Jupiter, 109 times the radius of the Earth, and 1/215th of an astronomical unit, the approximate distance between Earth and the Sun.

  7. Parsec - Wikipedia

    en.wikipedia.org/wiki/Parsec

    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 for Distance star is in light-years).

  8. Oort cloud - Wikipedia

    en.wikipedia.org/wiki/Oort_cloud

    The Oort cloud (/ ɔːrt, ʊərt /), [ 1 ] sometimes called the Öpik–Oort cloud, [ 2 ] is theorized to be a vast cloud of icy planetesimals surrounding the Sun at distances ranging from 2,000 to 200,000 AU (0.03 to 3.2 light-years). [ 3 ][ note 1 ][ 4 ] The concept of such a cloud was proposed in 1950 by the Dutch astronomer Jan Oort, in ...

  9. Proxima Centauri - Wikipedia

    en.wikipedia.org/wiki/Proxima_Centauri

    Proxima Centauri is the nearest star to Earth after the Sun, located 4.25 light-years away in the southern constellation of Centaurus. This object was discovered in 1915 by Robert Innes. It is a small, low-mass star, too faint to be seen with the naked eye, with an apparent magnitude of 11.13. Its Latin name means the 'nearest [star] of Centaurus'.