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  2. Astronomical unit - Wikipedia

    en.wikipedia.org/wiki/Astronomical_unit

    This is because the distance between Earth and the Sun is not fixed (it varies between 0.983 289 8912 and 1.016 710 3335 au) and, when Earth is closer to the Sun , the Sun's gravitational field is stronger and Earth is moving faster along its orbital path. As the metre is defined in terms of the second and the speed of light is constant for all ...

  3. Solar radius - Wikipedia

    en.wikipedia.org/wiki/Solar_radius

    Evolution of the solar luminosity, radius and effective temperature compared to the present-day Sun. After Ribas (2009) [3] The uncrewed SOHO spacecraft was used to measure the radius of the Sun by timing transits of Mercury across the surface during 2003 and 2006. The result was a measured radius of 696,342 ± 65 kilometres (432,687 ± 40 miles).

  4. Sunlight - Wikipedia

    en.wikipedia.org/wiki/Sunlight

    If the extraterrestrial solar radiation is 1,367 watts per square meter (the value when the EarthSun distance is 1 astronomical unit), then the direct sunlight at Earth's surface when the Sun is at the zenith is about 1,050 W/m 2, but the total amount (direct and indirect from the atmosphere) hitting the ground is around 1,120 W/m 2. [6]

  5. Astronomical system of units - Wikipedia

    en.wikipedia.org/wiki/Astronomical_system_of_units

    The astronomical unit of length is now defined as exactly 149 597 870 700 meters. [4] It is approximately equal to the mean EarthSun distance. It was formerly defined as that length for which the Gaussian gravitational constant (k) takes the value 0.017 202 098 95 when the units of measurement are the astronomical units of length, mass and ...

  6. Light-year - Wikipedia

    en.wikipedia.org/wiki/Light-year

    Reflected sunlight from the Moon's surface takes 1.2–1.3 seconds to travel the distance to the Earth's surface (travelling roughly 350 000 to 400 000 kilometres). 10 −6: 1.58 × 10 −5 ly: One astronomical unit (the distance from the Sun to the Earth). It takes approximately 499 seconds (8.32 minutes) for light to travel this distance. [28 ...

  7. Light-second - Wikipedia

    en.wikipedia.org/wiki/Light-second

    A light-minute is 60 light-seconds, and so the average distance between Earth and the Sun is 8.317 light-minutes. The average distance between Pluto and the Sun (34.72 AU [5]) is 4.81 light-hours. [6] Humanity's most distant artificial object, Voyager 1, has an interstellar velocity of 3.57 AU per year, [7] or 29.7 light-minutes per year. [8]

  8. The Sun is really loud — but if we could hear it ... - AOL

    www.aol.com/news/2018-02-26-the-sun-is-really...

    The Sun is said to be extremely noisy, but we can’t hear it since sound doesn’t travel through space. Scientists at the University of Sheffield decided to use vibrations within our star's ...

  9. 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).