New answers tagged

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Clarifications There is a difference between a solar flare and a the phenomena that cause things like the 1989 Quebec blackout and/or the 1970s New York blackout (I think it was 1972 but do not recall off hand). The latter phenomena are called coronal mass ejections (CMEs) because they actually involve large amounts (i.e., upwards of billions of tons) of ...


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Just to confirm that CuriousOne is correct as regards direct radiation damage to your body. From Solar Flares Solar flares are gigantic explosions associated with sunspots, caused by the sudden release of energy from “twists” in the sun’s magnetic field. They are intense bursts of radiation that can last for anywhere from minutes to hours. Solar flares ...


4

I believe the dyes behave similar to glow in the dark materials; They fluoresce a certain wavelength over time after being radiated. In the case of these shirts you'll have different chemicals for different colours, but which are all "activated" by UV radiation. There is a pretty nice explanation on Wikipedia, but basically this: You can excite an ...


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To discriminate between the other two answers. Lifetime spectroscopy would be capable of distinguishing between photochromism (in this case, reversible ultraviolet-switchable reflectance, example: hexaarylbiimidazole where the transition time is milliseconds to seconds) and ultraviolet fluorescence (where the "transition time" is zero, although the excited ...


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There is an explanation on the Del Sol web site but it omits the technical details. This is probably because Del Sol regard it as commercially valuable confidential intellectual property, and I have to concede that they are probably correct. Anyhow, some Googling has turned up a suggestion for how it works but there is no proof for this idea so treat it as ...


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A quick look at the Del Sol How it Works page shows their explanation, HOW DOES IT WORK? The Spectrachrome® crystal reveals color upon irradiation by ultraviolet waves; i.e., sunlight. When a flower blooms, the result is the exposure of the inherent color of the flower. A Spectrachrome® crystal is similar in that an energy-shift occurs causing the ...


1

Are there more positive than negative charges released? In general no, and this statement by itself would imply you were asking about whether the sun charges up, not about current. I wrote a detailed answer at http://physics.stackexchange.com/a/253491/59023 that explains why stars remain mostly neutral and that most observations [e.g., Bale et al., ...


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The sun is a ball of plasma. It is essentially a group of electrons and nuclei whizzing around. These electrons and nuclei correspond to no net charge. The get flung out into space still in the form of plasma. There is still no net charge. The individual particles have charge but no net charge.


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Just to more fully answer your question, here is an example of what differences in distances can mean mean as far as they affect gravitational forces. The planet Jupiter is extremely massive, and one side of one of it's moons, Io, feels a slightly larger gravitational pull than the opposite side. This difference in distance results in a gravitational force ...


1

If the sun were a true black body, then it would be black. The extent to which it differs from a true black body can be seen from the sun-light spectrum outside the earth's atmosphere. Overall, it is pretty close to a 5778 K black body, so the sun will likely be very dark if you remove its own thermal radiation. Upon closer inspection, you can see that it ...


3

The Sun pulls on the Earth as well. So both Earth and Moon are "falling towards the Sun" all the time, just as they are moving in almost the same orbit. Earth causes the orbit of the Moon to "wobble" a little bit. If you were simply given the coordinates of the Moon as it moves around the Sun, you would notice there is a deviation from the expected ellipse ...


1

The surface of the Sun, as you can see from the following picture, is not uniform: But it is impossible to see it with your naked eye. You will need a telescope and specialized solar filters (more information here). Notice also that the picture is not showing visible light, but extreme-ultraviolet light. You will need a special telescope for that. Or you ...


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Short answer, the sun isn't on fire. Flames can flicker with wind or with pockets of fuel that might collect and burn in spurts or bits of water that can steam when the flame touches them, causing movement, or due to small bits of turbulence as the heat expands away from the flame. The visible surface of the sun is much more like a hot iron that has a ...


3

All the neutrino detectors we have or might build will have course angular resolution because they detect the direction of scattered products of neutrino interactions rather than the direction of the neutrinos themselves. Worse, the solar neutrinos are relatively low energy (a few MeV), which means the scattering angles are large. Yes, we could accumulate ...


3

You sound disappointed that the earth hasn't yet collided with the sun. Applying random formulas to a physical situation is never a good idea. I suspect that the formula you are having issues with is for two bodies in space which are not in orbit around one another, as unfortunately the earth is with the sun. When one body orbits another, the motion of ...


2

The answer you refer to is to a question where both bodies are initially motionless. That's not the case for the Earth/Sun system. The Earth orbits the Sun. The gravitational force the Sun exerts on the Earth provides the centripetal force needed to keep the Earth in a stable orbit. In a sense the Earth is constantly free-falling towards the Sun but ...


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As stated in the answer you link, that formula is for 2 bodies starting from rest. The Earth and Sun are not at rest relative to each other, they are in orbit at a relative tangential speed of nearly $30\,{\rm km}\,{\rm s}^{-1}$.


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To add to the answers so far, here's a outline of a pretty crude calculation you could do. Let's assume the house is in space. That way, we won't have to worry about the other parts of the Earth equilibriating with the house. Now let's assume your house is a perfect blackbody (which may or may not be a good approximation depending on how your house is ...


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Yes. All matter that interacts with light absorbs it to some degree. This is true whether you're discussing UV or infrared or visible light. For example, the earth wouldn't be nearly as warm as it is if it didn't absorb visible light.


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Yes, it would, though not as quickly as if you were getting the full spectrum of sunlight. All frequencies of the light spectrum carry energy, so it becomes a question of how much of that energy is absorbed by the house. For example, if your house was completely black, all that visible light energy would be absorbed by the house and converted into heat. If ...



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