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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. 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]

  4. File:Scale model of Solar System 10 billion to 1.svg - Wikipedia

    en.wikipedia.org/wiki/File:Scale_model_of_Solar...

    English: This 10 billion to 1 scale model of the Solar system can be placed into hallways of most school buildings. The inner solar system can be placed inside, while some or all of the the outer planets are typically placed outside, with Neptune at a distance of 450 meters from the Sun. Students can copy the drawings by hand on index cards or cut them out and glue or tape to the cards.

  5. Solar irradiance - Wikipedia

    en.wikipedia.org/wiki/Solar_irradiance

    Irradiance in space is a function of distance from the Sun, the solar cycle, and cross-cycle changes. [2] Irradiance on the Earth's surface additionally depends on the tilt of the measuring surface, the height of the Sun above the horizon, and atmospheric conditions. [3] Solar irradiance affects plant metabolism and animal behavior. [4]

  6. 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).

  7. Solar constant - Wikipedia

    en.wikipedia.org/wiki/Solar_constant

    The angular diameter of the Earth as seen from the Sun is approximately 1/11,700 radians (about 18 arcseconds), meaning the solid angle of the Earth as seen from the Sun is approximately 1/175,000,000 of a steradian. Thus the Sun emits about 2.2 billion times the amount of radiation that is caught by Earth, in other words about 3.846×10 26 watts.

  8. 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 ...

  9. Geometrized unit system - Wikipedia

    en.wikipedia.org/wiki/Geometrized_unit_system

    We can convert a mass expressed in kilograms to the equivalent mass expressed in metres by multiplying by the conversion factor G/c 2. For example, the Sun's mass of 2.0 × 10 30 kg in SI units is equivalent to 1.5 km. This is half the Schwarzschild radius of a one solar mass black hole. All other conversion factors can be worked out by ...