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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Does Blue Light Really Have a Dark Side?

I was reading the following article on Wikipedia which discusses the dangers of blue light: Blue-light hazard is defined as the potential for a photochemical-induced retinal injury resulting from ...
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Don't we know how the magnetic field of the Sun is created?

This is how Wikipedia explains stellar magnetic fields: Stellar magnetic fields, according to solar dynamo theory, are caused within the convective zone of the star. The convective circulation of ...
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Is deep-space radiation greater in the Sun, or in the shadow of Earth?

https://space.stackexchange.com/questions/604/is-it-possible-to-get-pregnant-through-natural-means-in-space indicates cosmonauts are at risk of irradiation whilst in space. What little I know about ...
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Was Aristarchos' method to compute Earth-Sun distance ever rediscovered in medieval or modern times?

Ancient Greek astronomer Aristarchos who lived around 300 BC found a method to compute the Eart-Sun distance by applying geometry. In this video about the cosmic distance ladder, at 26:30, Terence ...
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Surface UV exposure with cooler star

If the sun's surface was ~ 4000K (and earth closer to compensate), the UV component of the radiation would be less. However, UV makes ozone via photolysis of oxygen. Also, the stratosphere would ...
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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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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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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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Why the radiative zone of the sun rotates uniformly, while the convective zone of the sun rotates differentially?

Wikipedia says this about the tachocline This is a region where the sharp regime change between the uniform rotation of the radiative zone and the differential rotation of the convection zone ...
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43 views

Is there a way to see the sun's outer layers from earth outside a solar eclipse using polarization?

¿Is there a way to filter sky light using light polarization? in https://en.wikipedia.org/wiki/Coronagraph#Invention it says: High Altitude Observatory's Mark IV Coronagraph on top of Mauna Loa, use ...
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Formation of Red and blue bands in the sky

Today at the time of sunset I saw this The sky is divided into two parts one In red and one in blue which are very distinctive Can anyone tell how? The upper part of the image points towards the ...
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Do solar energetic particles follow the Parker spiral?

I understand that the solar wind follows the Parker spiral shape of the Sun's magnetic field, thus it is possible for solar wind from a point on the opposite side of the Sun to reach Earth. I have ...
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Is the surface temperature of the sun constant?

I was just wondering that during the suns mains sequence would it maintain a constant temperature at the surface and only cool once the hydrogen in its core runs out, or is it always slowly decreasing?...
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How does the energy of a solar flare propagate?

Does it radiate outward, spherically, or is it more directed? Is there some opening angle? Is it more complex than this?
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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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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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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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What are ShadowBands during SolarEclipse and how can it be reproduced?

I recently got to know about different phases of a solar eclipse and its impact on Earth and its living creatures.., but one of the most interesting and not well explained phenomenon is the ...
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Generic Rayleigh effect experiment - nothing happens for water

On youtube, a bunch of Rayleigh scattering experiments (e.g this one are set up with some compound being added to water in order to invoke the effect. Why is there no Rayleigh effect for "pure" water?...
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How to derive equation for time it takes photons to diffuse through the Sun

I am wanting to use the Rosseland radiative heat flux equation to find the time it takes for photons to diffuse through the sun. The answer I am wanting to derive is: $$\tau_D~\frac{\rho \bar C_p R^...
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What is this bright spot in the sky?

I took this picture a few minutes ago (35 minutes ago, currently 1828 here) As you can see there's a VERY bright spot on the right that shows a spectrum on the one side. I am pretty confident it's ...
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How close to the surface of the Sun would one have to be to determine an 'upright' position relative to it's surface?

As we stand upon the surface of the earth we're able to establish a relative 'up' and 'down' direction due to gravitational forces. As we leave the confines of the earths gravitational attraction ...
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How do I calculate the relative number of photons per wavelength emmited by the sun?

Assume I generate $n$ photons emmited by the sun. They have wavelengths between 390 and 750 nanometers. How do I find out the number of photons that correspond to each wavelength: How many of my $n$ ...
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What is the most likely cause for this strange lighting at sunset?

Yesterday's sunset was a little bit weird in several countries (Saudi Arabia, Egypt, Kuwait). Here's a video & picture, in case it wasn't clear enough it felt as if everything was being lit by a ...
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Luminosity of the sun

How is it that the total power generated by nuclear reaction in the core of Sun exceeds its total luminosity? Where does the difference go?
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Is it possible to approximate the solar radiation output for each hour of the day with the total output in a day?

If you know the total irradiance received by the sun during a single day, could you approximate how many irradiance each hour you get if you assume it was a clear day? I am able to calculate the ...
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What is angle between ray to center of the sun and its perimeter?

If I took a ray from a point on the earth P to the center of the sun. And another ray from the same point on the earth to the perimeter of the sun. What would the ...
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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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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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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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Interaction energy of stuff in the suns core

There is a post where CR Drost calculates the interaction engery in the center of the sun using only the density $\rho$ of the sun at it's center. Assuming that all the mass comes from protons we get ...
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Stars with same colour

This is the problem I'm trying to solve. When it says they have the same colour, does that mean that they have the same temperature?
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366 views

Determining rotational period of sun using sunspots

I know that at the equator at 0 degrees latitude , you could track a sunspot and then use T=2pi/w and w=∆theta/∆t to work out the period the equator rotates, but how would you do it for, say, sunspots/...
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In what ways does the sun output energy?

I'm curious about the energy output of the sun, and how it breaks down. What fraction is from EM radiation, solar wind, neutrinos, et cetera? How does energy output vary over the EM spectrum? I was ...
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Inclination of planets

What is the inclination of each planet with the equator of the Sun? Doesn't this have a relationship with the eccentricity of the planet's orbit?
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If the sun stopped burning, would we ever know it?

I read somewhere that since gravity moves at the speed of light, if the sun were to leave its position we would "know" about it through the absence of light and its gravitational effects on our planet ...