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- How much lux does the Sun emit? - Physics Stack Exchange
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
- optics - If the sea surface were absolutely calm should the Sun . . .
As the elevation of the Sun decreases and it moves from the zenith to the horizon, the glitter becomes more and more elliptical, until it becomes a ribbon as in your image On the other hand, if the water were completely still, with a smooth and horizontal surface, then the sun glitter ribbon would be gone, and you would just see a direct
- reference frames - Does Relativity make a difference on whether Earth . . .
Since the sun is so massive, this essentially constitutes of the Earth orbiting around the sun, as seen from any inertial frame of reference Of course moving to a frame of reference where the Earth is stationary we will observe the sun to be moving around us
- sun - Nuclear fusion - Hydrogen isotopes - Physics Stack Exchange
The main fusion reaction in the sun is the proton-proton chain reaction, which takes six protons and produces two protons, one alpha particle, two anti-electrons, and two electron neutrinos The deuterium nucleus is only barely bound and can be destroyed — dissociated into a proton and neutron — by absorbing a gamma ray with energy more
- thermodynamics - Black and white matters. But why and how? - Physics . . .
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
- astrophysics - Can Jupiter be ignited? - Physics Stack Exchange
It's fusing hydrogen into helium And it does this because it has so much mass that gravity is trying to collapse the star but the immense pressure means fusion takes place (creating an outward pressure to counteract the gravity pulling inwards creating a balance which must be maintained to keep the sun from collapsing inwards or exploding
- How is distance between sun and earth calculated?
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 ;-)
- How hot can metal get in sunlight? - Physics Stack Exchange
If the building is located in Hammerfest, Norway the metal might get warm to the touch If it's on the sun-facing side in Las Vegas you may find it gets hot enough to cause burns A definitive answer is not possible If people can touch it easily the temperature is a concern If it's out of reach, don't worry about it The iron isn't going to melt
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