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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What are the sources of error in the formula I derived to estimate sunrise and sunset times, and how can I improve its accuracy? [closed]

I derived the following formula to estimate sunrise and sunset times: $$ t=\pm\cos^{-1}\frac{\sin\theta-\sin L_{loc}\sin L_{sun}}{\cos L_{loc}\cos L_{sun}} $$ $L_{loc}$ is the local latitude $L_{sun}$...
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Do switchbacks occur in the radial direction of the solar wind magnetic field?

My question is: When we are talking about switchbacks, do we mean switchbacks in the radial component of the magnetic field or in the total magnetic field?
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Why do we sometimes refer to the solar wind as young solar wind?

Why do we sometimes refer to the solar wind as young solar wind? What does young imply?
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Measuring Sun and Moon distances to the Earth ratio just by observing angles of elevation if upper 50 percent of Moon's surface is bright?

When the next type of calculation was possibly used for the first time? If 50% i.e. upper half of Moon were bright would the Sun-Earth to Moon-Earth distances ratio be calculated from just ...
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Does the sun's electromagnetic field disrupt communication?

If you were to design a drone or probe that could fly close enough to the sun to examine the corona, closer than the Parker Solar Probe, how close could you get and still have reliable communications ...
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What is the amount of mass ($\rm kg$) that the Sun loses daily in the irradiation form?

I had difficulties to post my question because the system asks me to detail my need more. Is it necessary? Doesn't my question make sense? There is no need to answer, I just want to know if there is ...
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Are there any effect of Sun to the tide? [duplicate]

The Earth is rotating for the Sun's gravitational field. Like a free falling object Earth should feel zero gravity to the Sun. So why there are effect of Sun to the tide?
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How much does the sun emits in the radio spectrum, compared to artificial (human) emissions?

I would like to compare natural vs artificial (human) emissions in the radio spectrum (f < 1 THz). The goal is to bring some scientific facts in the debate for deployment of 5G. It's easy to find ...
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Why does the solar corona appear white?

Look at this photo taken in France during the 1999 solar eclipse which I found on Wikipedia. Why does the corona appear white? It has a temperature of about $10^6\,$K so you would think that it would ...
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Pool cover efficiency of absorbing and retaining heat in pool water

Looking into the options of adding and retaining heat in the outdoor pool (and saving wallet) - heat inverter, roof solar water heater, gas heaters etc. the pool cover seems to rule them all (at least ...
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Problem regarding the absorption spectrum of the sun

Some of the wavelengths of light that are emitted from the sun will be absorbed by atoms in the outer layer of the sun and also the atmosphere of the sun, and we see this as absorption lines in the ...
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Why Sun's coronal belt is more stable at Sun's equator?

As the Sun's coronal belt is made up of protons and electrons constantly scattered by photosphere's sunlight and as these particles are forced to do loops due to Sun's magnetic field is it possible ...
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Why does the spectrum of Sun follow a black-body distribution curve?

Black-body radiation, as I understand it, is radiation in thermal equilibrium at a fixed temperature with a cavity. The spectrum of such radiation follows the famous black-body distribution curve. But ...
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Does the Sun have enough gravitation to bind its hydrogen/helium plasma?

"Does the Sun have enough gravitation to bind its hydrogen/helium plasma?" So my question arises from the fact that high energy (or high temperature in other words) hydrogen or helium gas ...
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How long could the Sun power the Earth?

With the energy emitted by the sun in 1 second, how long could everyone household on earth be powered? Currently we obviously can't harvest 100% of the sun's energy emissions.
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How does the Sun generate its energy?

We all know that the sun generates its energy from nuclear fusion in the core. The electromagnetic radiation produced slowly travels upwards, while constantly being absorbed and re-emitted by the ...
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How can I view through the water surface without reflection? [closed]

I am searching for a possibility to see the shallow grounds of water without reflections on the surface. I am sailing in an area where there are reefs and shallow coral patches which can be dangerous ...
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If the Sun shrunk to the diameter of the earth, would Earth be habitable? [closed]

I was thinking about the sun. What if it shrunk in diameter to the size of the Earth? It wouldn't change the gravity much. But would it change the heat? If so, would the earth become uninhabitable? My ...
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Entropy of photons in the Sun / Earth system - Do infrared photons have higher entropy than ultraviolet/visible photons?

The entropy of a photon gas in equilibrium (emitting e.g., black-body radiation; BB) is $S \propto V \cdot T^3$ where $V$ is the volume and $T$ is the temperature of the gas [see https://en.wikipedia....
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Why don't the nuclear fusion processes inside the sun produce electron antineutrinos $(\bar\nu_e)$?

Why don't the nuclear fusion processes inside the sun produce $\bar\nu_e$ despite having the same mass as $\nu_e$? Is the reason as simple as "there is no production channel for $\bar\nu_e$s.&...
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How are solar oscillations detected?

While reading through a page on beginner Helioseismology, I occasionally came across the terms p-modes or g-modes, which I know are caused by pressure and gravity. I wanted to know how do satellites ...
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Books for Solar physics

I am thinking about applying for an internship at a university under a professor who does Helioseismology. What resources would you recommend me for being ready for such an internship? Can you suggest ...
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Positron-electron anihilation in the Sun

As 75% of the Sun is Hydrogen and 25% Helium and the latter derives from 4 hydrogen atoms where half of protons that formed neutrons expeled positive charges as positrons that anihilated with nearby ...
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What would happen to the Sun if you reflect all its emitted e.m. radiation back? [duplicate]

What would happen to the Sun if you would reflect, in whatever way, all the outgoing electromagnetic radiation (Solar winds can be neglected)?
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Is it possible to make the Sun spin a coin in space?

Is it possible to do anything to a coin in space, so it begins to spin, using sunlight as the energy source?
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What is happening when magnetic field lines snap or break?

In discussions of sun spots and auroras on Earth, magnetic field lines are often described as "snapping" or "breaking", with the result of releasing charged particles very ...
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Where did the Sun get its angular momentum? [duplicate]

The planets in the solar system all travel around the Sun in the same orbital direction, which is also the direction in which the Sun itself rotates about its axis. Therefore our Solar system has ...
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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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