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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5answers
18k views

Why is spectrum obtained by sunlight, said to be continuous?

My teacher spoke about atomic spectra today, and he explained that, unlike the spectrum obtained by analyzing the sunlight, the spectra of atoms are not continuous. I have a question about this - ...
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20 views

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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234 views

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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Gravitational field of sun [closed]

Let there be a solar system without Earth. Now what happen if we place the Earth suddenly on its actual position does the gravitational force of sun acts on it immediately because of its pre ...
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1answer
126 views

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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Density of the Sun

Being either on the surface or somewhere inside; where is the density of the gases of the Sun equal to the density of the ground we stand on here on earth?
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Can human push Earth away from the Sun?

It's said the earth is approaching the sun. Can we push it away little by little? Although we can emit rocket towards the sun, but it's too expensive to make a rocket: So I think maybe we can ...
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618 views

Has Voyager 1 entered a solar radiation belt?

The Voyager 1 probe was sent out in 1977 to go where no man made object has gone before, after more than 35 years it’s still going strong. It’s now 124 AU away from Earth and many are wondering when ...
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1answer
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Sun’s corona is so much hotter than Chromosphere [duplicate]

What makes Sun’s corona so hot? I tried to google it but can’t find satisfactory answer.
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1answer
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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1answer
59 views

How is the constant “284” derived within the Solar Declination Angle equation?

How is the constant "284" derived within the Solar Declination Angle equation? The earth's axis results in a day-by-day variation of the angle between the earth-sun line and the earth's ...
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1answer
408 views

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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1answer
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How thick would the atmosphere have to be to block all the sunlight?

this is a question I haven't been able to find an answer to anywhere. How thick would our atmosphere have to be for the surface of the planet to be completely dark? Is that even possible? Thank you!
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Parker Solar Probe passing extremely close to the Sun; what relativistic effects will it experience and how large will they be?

note: This is a question about relativistic effects. I've included some detail about the spacecraft and its orbit for background, but the question is about relativistic effects and their observability....
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1answer
34 views

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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How can Sun burn in space?

If there is no oxygen in space how can sun burn in space. (even though I know fire is caused by nuclear reaction inside sun)
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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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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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1answer
144 views

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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1answer
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How to correctly calculate the colour of the sky?

It is well-known that the sky is blue due to Rayleigh-scattering. What bothers me though is the question how to actually calculate the spectrum of the scattered sunlight. Yes, use one of the formulas ...
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1answer
3k views

Why is the Sun made of light elements only?

Since the entire solar system inherits its heavy elements from supernovae unrelated to our star, I fail to understand why, while capturing most of said system's matter, the sun only contain light ...
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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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1answer
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Are the electrons at the centre of the Sun degenerate or not?

Trying to find an answer to this question, I came across two different methods of determining whether electrons at the center of the sun are degenerate or not. The first method, used here, calculates ...
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5answers
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Modeling incoming solar radiation

I want to write a model for estimating incoming solar radiation for a specific latitude on earth but I am struggling to find an appropriate source which shows the required equations for doing so. ...
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1answer
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Will the Sun's orbit around the Milky Way degrade once it transitions to a white dwarf with half its original mass?

Does the Sun's mass factor in at all when it comes to its orbit around the Milky Way, such that if it lost half its mass, its orbit would change? Or is it a matter of the center of the Milky Way being ...
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2answers
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Why the gravity of a black hole is so strong by the Bad Astronomer

In this bad astronomer video, Phil Plait says two things: 1) He first demonstrates the effect of gravity using paper, and he keeps a fixed mass and distance. However as he makes the paper smaller and ...
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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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Calculation of the temperature of the Sun's core? Why is this value so low?

From the Stefan-Boltzmann Law ($j^*=\sigma T^4$), the luminosity of the Sun is $L_{sun}=j^*A=[\sigma T^4][4\pi R_{sun}^4]=3.85\times 10^{26}$ W. If I assume the Sun to be in a steady state then the ...
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4answers
1k views

Does the sun have a black hole inside of it?

The Schwarzschild radius of the sun is approx. 3 km. It would be a black hole if all the mass of it were within the 3km. However, even with the mass spread out couldn't the sun technically have a or ...
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1answer
406 views

Solar granulation pictures showing a wonderous spatial resolution

Recently, I came across spectacular pictures of solar granulation like this: (source) The photograph is impressive because it has a resolution of less than 0.1 arc seconds, which corresponds to ...
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1answer
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What exactly is delta-14C and why are there periodic plateaus in the delta-14C curve?

I downloaded the IntCal13, IntCal09, and IntCal04 datasets (parent site), and when I plotted the last 24k years was surprised to see a plateau or even reversal appear every ~5300 years. Apparently we ...
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6answers
10k views

If the moon had a mirror surface, would the earth be equally illuminated as by the sun during full moon, or would it require a different mirror shape?

Suppose the apparent diameters of the sun and the moon are exactly the same (which in fact very close to the real situation). If the moon had a perfect mirror surface, would the reflected visible ...
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How do neutrinos pass through the sun so quickly?

If it takes thousands of years for light to escape our sun then how can neutrinos generated in the very center of the sun reach earth in just 8 minutes? Why is their speed so great that they can ...
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2answers
277 views

Is an obsidian plate safe to use as a Sun viewer? [closed]

Is a 0.5 cm thick obsidian plate good to see the Sun directly?
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1answer
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Can RGB screen color exist in real physical world?

For example the bright royal blue color; R0 G10 B220, HEX: #000ae1. I know this color cannot be printed nor painted. But can this blue color exist in the real world other than on a digital screen? For ...
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2answers
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Size of iron sphere with mass of our sun [closed]

What would be the diameter of a sphere of iron with the mass of our sun? Use standard density of metalic iron. I realize it would then collapse into a star in its own right and become much smaller as ...
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1answer
133 views

Where is nuclear fusion occuring in the Sun?

My understanding is that the sun is basically a sphere of hydrogen with a helium core, and that the hydrogen is undergoing nuclear fusion to produce helium. There are many images and cross-sectional ...
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2answers
2k views

How to calculate the amount of night time during a flight?

I have been asked to find a way to calculate the amount of time that a flight takes during night time. So far, I have the departure latitude and longitude and the time of takeoff, the arrival ...
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1answer
1k views

Calculating time from altitude of the sun

If I know the angle between the sun and the horizon, the latitude and longitude of the location, and the day, what equations are needed to calculate the time? I found a website to do it: http://aa....
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3answers
80 views

Radius of the Sun

Is it possible to calculate the radius of the sun with minimal amount of physics? I couldn’t find resources on the internet that gives me an answer using a theoretical formula. You are given values ...
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1answer
2k views

Could we survive if the Sun were a black hole? [closed]

Ignoring the impossibility of the sun suddenly collapsing, and the energy release (which would kill us): If the sun suddenly turned into a black hole, could we survive if we had sufficient energy for ...
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2answers
95 views

What is the reason for the emission of electromagnetic waves from the sun? [duplicate]

What is the reason for the emission of electromagnetic waves from the sun and why curve its in about the visible light is maximum?
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2answers
83 views

How much change in Earth's orbital distance to change average temperature by 1°C?

How much closer/farther would the Earth need to be to/from the Sun to effect a $1 \sideset{^{\circ}}{}{\mathrm{C}}$ increase/decrease in average temperature?
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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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1answer
109 views

How many times do solar protons repeatedly fuse and fission before they form deuteron

In the proton-proton chain reaction in the Sun, the first step is $$p + p \rightarrow \; ^2_2{\rm He} .$$ After this, the most likely thing to happen next is that the reverse reaction occurs: the $^...
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3answers
83 views

Is there a difference between the red sky in the morning and in the evening?

It certainly has a different feeling to it, but does the temperature or earth's rotation or the clouds or anything else really make it two different physical phenomena or at least different colors? ...
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1answer
31 views

How much does time-dilation effect our observance of the most massive objects in our solar system?

Disclaimer: I'm kind of a newb, so I apologize if this question is not well formed. Please comment if anything is unclear, and I will do my best to make corrections. Reading this post about time ...
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1answer
229 views

Spacetime Mercury vs Earth

What is the time dilatation between the planets Mercury and Earth? Can a person survive on the dark side of Mercury in the In the L2 position to Mercury and the Sun?
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1answer
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If the Sun had a larger surface temperature how would that affect its appearance to us in the sky?

I thought about this when I came across wiens displacement law which says the higher the temperature, the lower the peak wavelength. If the sun was a lot hotter, and its peak wavelength wasn't in the ...
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3answers
10k views

Why is the Sun almost perfectly spherical?

Relatively recent measurements indicate that the Sun is nearly the roundest object ever measured. If scaled to the size of a beach ball, it would be so round that the difference between the widest ...