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On average, how much of the sun's energy that reaches Earth's outer atmosphere is reflected back into space?

On average, how much of the sun’s energy that reaches Earth’s outer atmosphere is reflected back into space?


  1. What happens when solar irradiance reaches Earth? Only about 70% of the energy that reaches Earth is absorbed, while the other 30% is reflected back into space by atmosphere and aerosols, ocean/land and clouds, as seen in this animation.A closer view reveals a delicate balance between absorption and reflection as well as a release of energy by rocks, air and sea warming and emitting increasing amounts of thermal radiation (heat) in the form of long-wave infrared light. This radiation allows Earth to lose heat at the same rate it gains from the Sun.
    Note: You need to move the round thing back again a little bit.

  2. For any planet with a moon, the planet’s mass can be approximated by GmM/r² = mv²/r = mrω² = mr(2Ï€/P)², where G is the gravitational constant, m the mass of the moon, M the mass of the planet, r the distance between planet and moon, and P the period of the moon. The mass of the moon cancels out, leaving
    M = r³(2π/P)²/G
    The masses of moonless planets have to be determined by Perturbation Theory, the effect of one planet’s orbit on the orbits of other planets.
    The diameter of another celestial object can be estimated by multiplying the angle subtended by the object by its distance from us. A closer estimate is obtained by
    d/2 = Dsin(α/2)
    where d is the diameter, D is distance to the object, and α is the subtended angle


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