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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Magnetic islands formed after magnetic reconnection

I often read about magnetic islands forming as a result of magnetic reconnection? To my understanding, those are irregularities of the magnetic field right? If not, could someone help me understand ...
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Is the yellow Sun light produced by photon scattering inside the Sun?

If the hydrogen emits four distinct light frequencies as a gas and on the Sun surface the gravity cannot alter hydrogen state as a gas does the yellow component of sunlight come from its interior?
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Mysterious - different speeds at different latitudes of the Sun

I recently read here (Hyperphysics page on Sun) since the Sun is a gaseous body and hence different latitudes can rotate at varying speeds. Naively, I was guessing that the poles would have faster ...
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Is peak temperature equivalent in east and west facing buildings?

East-facing condos/apartments are considered more valuable than west-facing condos by some due to perceived superior light quality and lower peak temperature. My assumption is total solar heat gain ...
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Cumulative Sun's radiation pressure exerts on Earth's surface

I have some discrepancies in what is in "Optics" (E. Hecht) and what I calculated, but it's simply formula, so I'm confused. I used: $$F = \frac{\pi R^2 S}{c}$$ to calculate cumulative force of ...
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Are solar flares and solar winds the same?

A solar flare contains high energy protons and particles. A solar wind is a stream of energized & charged particles primarily electrons & protons. I am confused whether both are same or not? ...
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How big a coincidence is the Sun and Moon having almost equal apparent sizes?

It's consensus that the very similar apparent sizes of the Moon and the Sun as seen from Earth is a coincidence (as already answered in this site). This provides us with almost exact total solar ...
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Why does the sun have the Fe?

I read the information about 'Abundance in the sun for the elements'. There are a lot of elements in the Sun. I thought 'how is it possible to exist Fe, Au, and so on in the Sun ?', but I couldn't ...
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Why does the Sun rotate?

On its axis, with a 24 day period, that is. It seems that angular momentum conservation alone would be a completely insufficient mechanism to maintain rotation against molecular friction over ...
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Function of solar radiation spectrum

I want to calculate the area under a curve between 250nm to 300nm to find the irradiance in [W/m2], to do this I think must find the function of Spectral Irradiance (sunlight out the atmosphere, ...
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Best numerical simulations of Sun's magnetic field

I was trying to find some simulations of the Sun's magnetic field. Which ones are the most accurate to date? Thank you!
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Fraunhofer line width

What sets the width of Fraunhofer lines on the solar spectrum ? I first thought of Doppler broadening, but numerical applications result in much too high temperatures. For instance, using these data,...
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What will be the mass of the sun when the core is depleted of hydrogen about 5 billion years from now?

Our sun converts 600 million tons of H to He every second, that is 5 million tons of matter into energy through nuclear fission. However, as the core of the sun continues to shrink the outer layers of ...
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Eye seen in sunglasses reflection

Today while laying down on the floor, enjoying morning sunlight I have noticed an interesting phenomenon. It is important to mention that I was wearing sunglasses - just regular, without any ...
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Sun light and leaf color

Wien's displacement law : $\lambda_{peak}T=2.898\times 10^{-3}m\cdot K$ Temp of sun = 5000 so sun radiate green wave in max volume. but atmosphere of earth refract sun light and blue wave is max ...
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When should I open/close the windows/curtains to keep the room cool in summer?

Folk wisdom has it that in order to keep your room cool, it's best to close the window. I assume the reasoning is that while a breeze of air feels cool, in most traditional houses the outside air ...
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Is the infrared sunlight collimated at ground level?

Is the infrared light from the sun (above 700nm) collimated like the visible spectrum or does it become diffuse due to the atmosphere? I mean during direct sunlight, so a clear sky. Basically, I want ...
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Artificial sun Sculpture [closed]

I am designing a dynamic sculpture of the solar system, about 6,500 feet long from the sun to Neptune. At this scale the sun will be 24 inches in diameter, Earth a quarter of an inch. Every hour the ...
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Calculating partition function at the core of the Sun, to use in the SAHA equation

I have to calculate the percentage of ionised Hydrogen in the core of a star with conditions similar to that of the Sun, using the SAHA equation. As part of this I have to calculate the partition ...
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Thermal velocity of electrons and protons in solar Corona

I would like to know how much (in eV) is the thermal velocity of electrons and protons in the lower solar corona? Thank you in advance!
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How do we exactly use neutrinos to probe the core of the Sun (if they can only interact weakly)?

Neutrinos are interacting with ordinary matter weakly. They pass through matter mostly unimpeded. Thus, neutrinos typically pass through normal matter unimpeded and undetected. Neutrinos' low ...
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Difference between alfven waves and magnetic fluctuations in solar corona

I have read in this paper https://arxiv.org/pdf/1911.07973.pdf about particles being accelerated in the solar corona either by Alfven waves (to my understanding when the turbulence is weak) or by ...
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Other than magnitude what are the differences between CME's and Solar flares?

I could not understand the differences between a CME and a Solar flare, aside from the fact that they differ in magnitude.
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Energy spectrum of Solar energetic particles (SEP's)

I would like to know if we have obtained any observations regarding the energy spectrum of solar energetic particles. Something like the following histogram : And if so, what is the index of the ...
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Should the centripetal force of Earth's orbit around the Sun affect a pendulum on Earth?

Lets use approximate earth angular velocity around the sun with $\omega\approx2*10^{-7}\frac{r}{s}$ and earth translation orbit radius with $r\approx1.5*10^{11}m$ we can approximate centripetal ...
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Why do sun light rays that come through clouds not look parallel, despite it being so far? [duplicate]

I was at the airport last friday and there were some nice sun light rays, although not much of a good spot to take a picture. What weirds me out every time I see them is that they look as if coming ...
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How many $pep$-related electron-neutrinos $\nu_e$ does the Sun produce?

In the sun neutrinos can be produced by the rare proton-electron-proton (pep) reaction: $$ {}^1_1 H + e + {}^1_1 H \to {}^2_1 H + \nu_e $$ How many pep-related electron neutrinos does the Sun ...
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Do neutrinos not interact with any kind of photons?

If billions of neutrinos reach us from the Sun why there is no any reflection of photons emitted from Earth to be reflected from them? Is this they are not interacting at all?
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How viscous is the sun core?

How the heat getting transfer from centre to outside the core? Is convection dominant here or radiation heat transfer mode? Is viscosity a relevant parameter in describing the macroscopic motion of ...
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How much solar power in kWH is there in the stratosphere during the day? [closed]

The stratosphere is above much of the atmosphere. People have talked about collecting solar energy there and beaming it back to Earth. How much power are we talking about?
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Difference between primary and secondary rainbow

A secondary rainbow is dimmer than a primary rainbow. A primary rainbow is seen as a result of two refractions and one total internal reflection. A secondary rainbow is seen as a result of two ...
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Thought experiment about if the sun was pure helium [closed]

Suppose you were to fix MSun and RSun – what would happen to the central temperature if the composition is (magically) transformed to pure helium (i.e., X = 0, Y = 1)?
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Why is the second stellar structure equation first-order ODE?

the 2nd structure equation is first order, but we seem to have two boundary conditions (e.g., $dP/dr = 0$ in a star’s center and $P=0$ at the surface) – but first-order ordinary differential equations ...
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Is it possible to land on sun?

The Sun is, of course, quite hot. A space probe built by normal materials probably would melt or burn even it’s still quite far from the Sun. However, from a theory point of view, is it possible to ...
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Are the muon/tau neutrinos produced in the Sun? If not, then where?

I was reading about Solar Neutrinos, and apparently they are all Electron Neutrinos. However, there are two other types of neutrinos, the Muon and Tau Neutrinos. Does the Sun produce them? If not, ...
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Can Earth's mass increase due to sunlight? With how much?

Asking this just out of curiosity: I am no physics buff but considering the particle nature of light, each photon has energy (however small it may be). Given this, can the earth's mass increase given ...
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Solar Oblateness: Understanding the force balance formula and solar radius in arcseconds

I have 2 questions regarding the following exam-style question and solution: Given a solar mass of $M_{\odot}=2.0 × 10^{30}\,$kg, a solar radius of $R_{\odot}=7.0 \times 10^8\,$m and a rotation ...
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Can artificial fusion have the same power density as in Sun's core?

I recently read about solar core, and found that the power density is only 276.5 watts per cubic meter. This seems rather low to me, but on the other hand the Sun is an enormous object, so the total ...
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Does the length of days change substantially during the year, from more than 24 hours to less?

I just read an article in the 'Science' journal online about Monarch butterfly migration. (Mysterious monarch migrations may be triggered by the angle of the Sun , by Elizabeth Pennisi , Dec. 18, ...
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What effect does color on the upper and lower side of umbrella have?

This question isn't referring to the general use of umbrella to provide protection from rain rather it concerns the optical effects of the color on lower and upper portion of umbrella. Umbrella are ...
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Finding how much time it takes for a complete Earth revolution around the Sun

Long story short, my brother made a joke about how stupid it is to celebrate the Earth making one "trip" around the Sun: New Year's Eve. So I got curious and was wondering: how could the first ...
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How is a horizontal sunset possible? [closed]

Source: @PHSXES/Reddit Normally, sunset moves vertically, from up to down in the sky. But in this photo, it appears to be moving horizontally, from left to right. It might be an instant of a ...
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Solar panel and Equinox

At Equinox the number of hours of daylight and night is equal so 12 hours of each... is this from 6am to 6pm? how can we know which hours this daylight happens for. The question is: Over which ...
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Why doesn't the Sun gravitate Mercury so that in following years, Mercury goes inside the Sun? [duplicate]

There has been news in public about Mercury that passes in front of Sun which happens very rarely every 100 years, here. So people on Earth can see it through special kind of telescope, of course, ...
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Units in Representation Of Energy Density Spectrum

In most of the texts, I referred to The Axis being labelled with Units as shown above. But I also found few images with different Notation (1/Units) Being Followed as shown Below. The units of the ...
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Do rainbows show spectral lines from the sun?

I'm aware of a similar question being asked in Do rainbow shows spectral lines?: The response to this question is that the body producing the light is not the water droplet that merely diffracts it ...
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How can I sample the solar spectrum to determine, in the vacuum of space, the frequency of a random photon?

I am working on improving a spacecraft charging model by simulating the photoelectric effect. To do so I need to determine the frequency of a random photon coming from the sun. How would I go about ...
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Could a foggy double-paned window be amplifying UV rays?

Ever since my living room double-pane window got foggy, I've noticed that I feel very uncomfortable/sick when it is a very sunny day (similar to the way I feel when I've been out for too long in the ...
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Solar astrophysics--flux derivation [duplicate]

The question reads: The solution reads: My only answer is for 4 and it is $\pi I_\nu$. Where did I go wrong?
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Superman threw a net with a lot of nukes into the Sun. What happens now? [closed]

The iconic scene in "Superman IV: The quest for peace" shows the eponymous character throwing a net filled with nuclear missles into the Sun. If that were to happen in real life, what would happen as ...

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