When you look 'at the world' (i.e. to the horizon) on a clear day, unlesss the sun is at a very low angle, the surface of your eye is not illuminated directly by the sun, only reflected sunlight from the atmosphere, ground and objects. The 32,000-100,000 lux figure is referring to a horizontal surface illuminated directly by the sun.

2015年9月22日 · The Sun has had plenty of time to reach an equilibrium between its self gravity and its internal pressure gradient, the dynamical timescale for the Sun as a whole is only $\sim (GM_\odot/R_{\odot}^3)^{-1/2} \simeq 1600$ s. Any departure from symmetry would imply a difference in pressure in regions at a similar radius but different polar or ...

2015年4月17日 · If we assume the Sun orbits the Earth, the math says that the Sun should be much less massive than the Earth. If we assume the Earth orbits the Sun, the opposite is true. Either way we can get an estimate of the mass of the Sun. We know from other tests that the Sun is more massive than the Earth, so therefore the Earth orbits the Sun.

2015年4月27日 · Another way of calculating the earth - sun distance is to look at the centrifugal and the gravitational force. This solution assumes that one already knows the mass of the sun, but thats a different problem ;-).

2013年3月31日 · In principle the tidal forces of the Sun will eventually slow the Earth's rotation so it always shows the same face to the Sun. However I suspect this would be such a slow process that the Sun will have formed a red giant and swallowed the Earth before it's complete. However it is not unknown for the axis of rotation of planets to change.

2017年2月15日 · The Sun has actually set/risen and we see it due to the way light is bent across the atmosphere. Apparently due to coincidence of the size and distance of the sun, its exactly the same size - so if we see 50% of the sun, the sun is 50% below the horizon. So, I understand all this, so here is my question :

2022年3月27日 · The continuous spectrum of the visible photosphere of the Sun is attributable to the radiative equilibrium of the $\mathrm{H}^{-}$ ion. This has been recognised for at least 80 years ( Wildt 1939 ). This ion forms by the attachment of a free electron (with a continuous spectrum of energies) to a hydrogen atom, emitting a continuous spectrum of ...

Another is the fact that true Sun's path, the ecliptic, makes a $23.5^\circ$ angle with the celestial equator, which also causes seasonal variations in true Sun's speed along the celestial equator. To get around these problems, astronomers invented the "mean Sun" for timekeeping, and it moves at a uniform rate (not a variable rate) along the ...

2025年2月12日 · Title: Review: Sun Spa, Vienna. JoJo Date: Feb 6, 2025 Phone: 3479065988 City: Vienna State: VA Location: Gallows rd / Electric House Fee & Tip (if applicable) 140+400=540 total Nationality: Chinese Age Estimate: 25-30

2014年7月3日 · The visible has about half of the energy coming from the sun on the surface, as seen in the link. So a metal door in the sun will transfer the heat of the visible spectrum to the interior if painted black, will reflect it back and keep the interior cooler if painted white. It is a good reason for painting roofs and walls white in hot countries.