Questions tagged [sun]

The Sun is an almost perfectly symmetric yellow dwarf star [spectral class G2V] which is at the center of our Solar System.

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Living at the equator (Colombia), how to figure out the orientation towards north using the sun falling through a window?

The real life issue is this: A friend is moving to a new apartment. What is bad here, is if the apartment is getting full sun in the morning or afternoon. So the Sun goes from east to west, right? If ...
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Ray sun heating

I recently got a curious question about the sun rays. Is there a material that can absorbs most of them and turn it into pure heat? For example, we all know that dark material (black t-shirts) get ...
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552 views

Why are there dark lines in an absorption line spectrum from the Sun? [duplicate]

Consider this image and quotations from Basics of Radio Astronomy for the Green Bank Telescope: When a continuous spectrum is viewed through some cool gas, dark spectral lines (called absorption ...
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What would happen if gamma-ray burst from a supernova burst hit the sun? [closed]

What would happen if gamma-ray burst from a supernova burst hit the sun? Would the sun explode? Would the sun expand. Have a longer lifetime? Shorter Lifetime? Because people are nit-picky about stuff ...
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What is meant by “stable/unstable to convection” in the context of the solar atmosphere?

In studying the Schwarzschild stability criterion (for the solar atmosphere); $$\left\lvert\frac{dP}{dr} \right\rvert\lt\frac{\gamma P}{\rho}\left\lvert\frac{d\rho}{dr}\right\rvert$$ From my notes are ...
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Is there any way looking at Stars from that I can understand that we are revolving around the Sun?(Not caring about other planets for now)

I am learning Astronomy. I videos or lessons I look at are already biased over heliocentric math to explain the parallax concept. I am looking for an intuition to get myself a deeper understanding of ...
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Is the reason the sunshine is 'extra bright' after rain due to refraction of the additional water in the air?

Quite frequently after the sun comes out after rain I experience a 30 minute period where the sunshine is 'unusually bright'. Such that it makes my eyes water. My question is: Is the reason the ...
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115 views

Why does the gas in Sun's outer layer not expand?

Since in the outer part of sun it consists gases. Why don't the gases expand due to heat? This was asked by my friend. And he said that the gases are attracted by the plasma layer by a force. So the ...
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Some Rayleigh Scattering questions

Last week I've heard about Rayleigh scattering for the first time, when the classic 'why is the sky blue?' question has crossed my mind and I must admit that it is fascinating! However, I do have a ...
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What if the luminosity of Sunlight increased by 10% [closed]

If the luminosity of sunlight increased by 10%, would people be able to survive outside? Would such brightness of light be very harmful to them, for exemple as much as the Mercury Vapour Lamp without ...
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Radiative Forcing

In a first approximation the radiative forcing $RF$ is related to the temperature change by the linear relation $$ \Delta T = \lambda \, RF $$ where $$ \lambda\approx 0.8 \, \frac{{\rm K}}{{\rm W}/{\...
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What is the difference between granulation and supergranulation in the Sun's photosphere?

Granulation and super granulation seem to be some sort confused topics as they are due to the heated particles coming out of the surface. What is the difference between the two?
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Speed of sound at the Sun surface [closed]

The gas velocity at the Sun's surface is subsonic and At 1 AU from the sun, the solar wind is supersonic. Like Parker wind solution. Why the velocity at the Sun's surface is subsonic? (In the ...
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What is an active region in sun's photosphere? Why sometimes there is an active region but no sunspots?

What is the theory behind an active region? If we check data in solar monitors, there are some cases where there is no sunspot but there is still an active region. Why is that the case?
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How loud is the sun? [duplicate]

The sun is a continuous explosion. The reason we cannot hear the sun is because of the vacuum separating us. If that space was to be filled with air, would the sun be audible?
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Can you destroy the Sun if you throw enough iron into it? [duplicate]

i have a vague understanding of how the inside of the sun works, but i remember from class that when the sun started "making" iron on it's core, it cannot go further; can't make a heavier element. ...
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202 views

What determines the surface temperature of the sun?

The core temperature of the sun is on the order of 15 million degrees kelvin while its surface temperature is around 6000k. What are the main factors which determine the surface temperature of the ...
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Does the Sun revolve around the supermassive black hole at the center of the Milky Way? [duplicate]

I'm curious to know, does the sun really revolve around the black hole at the center of the galaxy?
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Why acoustic glitches in stars translate into extra oscillatory components in the normal frequencies?

Acoustic glitches are locations inside the star where the sound speed changes abruptly compared to the wavelength of the acoustic waves that propagate through. Examples are the ionization zones and ...
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239 views

What are the average wavelengths and brightnesses of sunlight across the stages of twilight?

I understand that before sunrise, twilight shows several colors, so I'm looking for the average color (wavelength) and brightness (lux) of light that is being projected from the sky before the sun ...
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122 views

What would the sky look like if the Sun was a black hole?

As a complement of this Phys.SE question. What kind of lensing and diffractions effects from space would be perceived on earth?
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What portion of the total power emitted by the Sun comes from photons?

We usually talk about luminosity, which is the total power from emitted photons. The other sources are neutrinos and the solar wind (which includes protons and other particles). I assume that most ...
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179 views

Solar Neutrino Problem [closed]

I am not sure if this has been asked recently, but has there been any headway into solving the solar neutrino problem? I recently completed the Particle Physics for non-Physicists by Professor ...
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how to get high humidity and low temperature in room [closed]

I want to start mushroom farm for that I have to maintain high humidity and low temperature for that ,So i finding solution for how to get high humidity and low temperature at low cost.
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Nuclear Fusion requirements?

So I kept searching for answers or reasons as to why the sun can generate nuclear fusion at 15 million degrees C when I research that nuclear fusion is achieved at 100 million degrees. Is it because ...
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How to calculate the Sun’s energy output? [closed]

What formula can be used to find the total energy being produced from the Sun in Joules per second? If I recall correctly, the energy is around $2.3012 {\cdot} {10}^{27}\,\frac{\mathrm{J}}{\mathrm{s}}...
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Proof against Tychonian model by view from Space

No earth-based observation of the planets can disprove the Tychonian model (planets orbit sun, which orbits the earth). It takes very fine stellar observations, which couldn't be done in the 17th ...
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What if we throw many buckets of water into the Sun?

What will happen if we throw many buckets of water into the sun and keep repeating the process? Will it get cooler or hotter?
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What would happen if Jupiter collided with the Sun?

This question is inspired by a similar one asked on Quora. Let's say a wizard magicked Jupiter into the Sun, with or without high velocity. What happens? The Quora question has two completely opposed ...
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Does the photons of light have an effect the movement of solar planets

In space, solar sails are used in order to move some space exploration crafts. Since in space there is vacuum the slightest force could be enough to propel and move the craft. Although the earth is ...
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Electron density in the sun

I'm currently working on solar neutrino and in order to make a numerical simulation, I need the potential felt by electron-neutrino : \begin{equation} V_e(r) = \sqrt{2} G_F N_e(r) \end{equation} where ...
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How much of Sun's mass is “regular” matter? How precisely do we know Sun's composition?

This is a question which spun of this Can the Sun / Earth have a dark matter core? I have argued that it is possible to pretty accurately estimate how much mass of Sun is in the regular matter, so ...
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Describing the Sun's interior

Can the interior of the Sun be described as an ideal gas? From my knowledge, to describe a body of gas as an ideal gas, the separation between the particles must be much greater than the size of the ...
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What causes the perceived intensity of the sun to change on a short timescale?

I was inspired by this question to ask, what causes the "beating down" feeling of the sun to vary day to day? While the linked post explains why the sun feels hotter in the summer than in the winter, ...
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Why does the sun “beat down” harder in the summer - or does it?

I know that seasons are caused by the Earth's axial tilt - in summer, latitudes away from the equator receive more surface irradiance (power per unit area), and vice versa in the winter, because of ...
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The Sun is giving us a low entropy, not energy

While I was watching a popular science lecture on YouTube, I came across this sentence "Sun is giving us a low entropy, not energy" which was said by Prof. Krzysztof Meissner. I am not a ...
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Would I see a mushroom cloud if I nuke the sun corona?

The sun corona can reach an extremely high temperature at least a few million degree, say if the temperature of the explosion of a nuclear bomb is roughly equal to the temperature of the corona then ...
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Why the color of Sun is yellow, red or orange? [duplicate]

Theoretically the maximum wavelength of sun radiation is approximately 500 nm. Then we should see the sun as green. But why do we see sun as yellow, orange or red?
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How much time does it take in Earth to generate the energy supply that the sun produces in one second?

According to this article which I ignore if it's correct The amount of energy the sun emits every second is , the amount of energy the sun emits by second is 4x10^33 ergs . And according to this other ...
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Sun-path on the sky [duplicate]

We are standing on the Earth and we see Sun on the sky. We see it walking in a certain direction, with predictable moving. Earth is a spheroid, as we all know. It is circling around the Sun, and also ...
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Would the effects of a Coronal Mass Ejection be magnified in the South Atlantic Anomaly area?

The South Atlantic Anomaly is an area where the Earth's inner Van Allen radiation belt comes closest to the Earth's surface, dipping down to an altitude of 200 kilometres. This causes one of the ...
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Do coronal mass ejections and solar flares diffuse over long distances?

I understand that over great distances electromagnetic radiation such as light and lasers would diffuse greatly (much like a shotgun blast). Is this the same case for solar flares? If this is the ...
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Why does the full Moon appear?

I know that the full Moon appears when Sun, Moon and Earth are in a straight line, but if we consider that they are in straight line, why is the Moon illuminated? I mean to say that Earth should ...
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Celestial Body Approaching Speed of Light, “Observed” as a Black Ellipsoid?

I have an interesting question, one which I think may not work haha, but please bear with me. Let's work with our sun, with mass of about $2 \times10^{30}$ kg. According to the following formula, ...
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Are the planets revolving around the sun in perpetual motion? [duplicate]

I was wondering if the planets revolving around the sun are an example of perpetual motion. Will they ever stop the revolution?
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181 views

How to calculate the focal spot size of concentrated sunlight

I know that concentrated photovoltaic systems use Fresnel Lenses to concentrate incident sunlight to a point. I also know that this point isn’t infinitely small and has an actual size since the lenses ...
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Solar neutrino Spectrum - Why are there discrete energies for Be and pep?

What is the reason why some reactions give a continuum for the energy of the released neutrinos and others give only a discrete value ($\ ^7B$ and $pep$ )? Thanks for your help. Please feel free to ...
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What's the timescale for the formation of a coronal mass ejection?

How quickly does the sun form and release a coronal mass ejection? If we were watching the right part of the sun closely, how long would it take us to go from "nothing seems to be happening" to "...
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Estimating the temperature of the sun using Wien's displacement law

After previously deriving the frequency distribution of photons as $$u(\omega,T) = \frac{\omega^3\hbar}{\pi^2 v^3}\frac{1}{e^{-B K_B T} - 1}$$ I have been asked to estimate the temperature of the ...
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584 views

Is it possible to collimate a point source of concentrated light?

So I am wondering whether it would be possible to create an optical system that does and consists of the following: Use a Fresnel lens to concentrate direct sunlight to a point focus. I assume that ...