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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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How to convert $\ kWh/m^2 $ to $\ Joule/kg$. Comparing sun radiation over a location with the radiation produced by a CT scan [on hold]

How to convert $$\ kWh/m^2$$ to $$\ Joule/kg$$ I want to compare the radiation produced by the sun over a location (where I live in, measured in $\ kWh/m^2$), to the radiation a person gets from a ...
2
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3answers
76 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
23 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 ...
8
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1answer
81 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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1answer
32 views

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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1answer
51 views

How much does temperature affect the time of sunrise?

Please forgive me if this is a dumb question, or if my understanding of basic physics is wrong. Please feel free to correct me. As I understand it, if the Earth didn't have any atmosphere, then the ...
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0answers
21 views

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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1answer
52 views

Will a black body placed somewhere around the Sun obtain (eventually) the same temperature as the Sun?

Suppose we look (above the Earth's atmosphere) at the wavelength ($=\frac c f)$ spectrum emitted by the Sun: This shows that the Sun is approximately a black body with a temperature of about $5525(K)....
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1answer
59 views

Question about China's Artificial Sun

I have read recently in many websites dedicated to science that China has made an artificial sun hotter than the 'sun'. My question is how did they make a thing that can withstand such a high ...
1
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1answer
43 views

How does the Earth's radial acceleration affect it's velocity during orbit around Sun? [closed]

When the earth moves along its ellipse at $67,000mph $ it accelerates at $0.006m/s^2$ would it be correct to say it's speed at some points relatively increases by $0.006m/s$ every second
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1answer
40 views

What's the Earth's linear acceleration component around the Sun?

The earth's centripetal acceleration around the Sun is $0.006m/s^2$ does this mean one can say the earth's acceleration when it travels(revolves) at $670,000mph$ is simply equal to its centripetal ...
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0answers
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How does brightness affect color? [duplicate]

How does brightness affect the color of light? For instance, the sun might be yellow because of the blue scattering when the light travels through the atmosphere - but if you look at it, it seems ...
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2answers
110 views

Why does the sun always have some whiteness? [duplicate]

So the atmosphere scatters light on its way to earth, making the color of our sky. For example, when the sky is blue on a clear, sunny day, the sunlight appears somewhat yellow because the blue light ...
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1answer
70 views

How does Sun's fusion output compare to its gravity?

How does the total solar energy output compare to the total energy required to keep it contained (i.e. Sun's total gravity). In other words, is Sun's output "positive" if its gravity is factored in ...
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1answer
39 views

What is the incident power of the sun for different parts of the U.S over time?

I have seen number as low as $200\ \text{W}/\text{m}^2$ to $1000 \text{W}/\text{m}^2$. I'm in California and looking for information on how much power my solar panels will pick up. I have $4100\ \...
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1answer
52 views

Is the Earth orbiting an 'illusory' Sun, owing to the 'speed' of gravity? [duplicate]

We see the Sun about eight minutes after light left it. Presumably this means we are also experiencing the Sun's gravity 8 minutes after it 'left' the Sun. So are we orbiting around the Sun we can ...
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1answer
79 views

Does the sun have nonzero electric charge? [duplicate]

The sun is a star, meaning it's a ball of gas undergoing nuclear fusion in its core. The sun, like any other star, experiences line-driven stellar winds due to the transport of ions from its interior ...
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2answers
39 views

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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1answer
51 views

What's the eccentricity of our sun's orbit around the center of the galaxy? [duplicate]

Just thinking about "galactic habitability zones." Is this even a valid question?
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3answers
1k views

How massive is the Sun compared to other stars?

I was just reading "Rare Earth" by Peter Ward and Donald Brownlee and they claim that $95\%$ of stars are less massive than the Sun. But, I was always told the Sun is an average star. Which is it?
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0answers
24 views

If the Earth would change into a ball of water, how wil its form develop, considering only the Sun's and Moon's influence? [duplicate]

Let's fantasize that the Earth changes in a non-rotating ball of water. And let's assume the only gravitational influences on it are those of the Sun and Moon. What will happen to the form of the ...
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3answers
80 views

How to calculate weight of an object orbiting another object?

How do we calculate weight of an object which is orbiting another bigger object in the space? For example, comparing the pair of Sun-Earth, Earth is orbiting Sun due to the force applied by Sun on ...
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1answer
27 views

Gravitational/electromagnetic effect of planets on solar activity?

Does the gravitational and/or electromagnetic influence of planets have any effect or correspondence to solar activities (e.g. solar flares/CMEs) - and if so, does the planetary position (where they ...
2
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2answers
63 views

Why are clouds lighter than the sky during the day but darker at night

This is probably a very basic question but I couldn't find a good answer to it, most search results are about rain clouds or clouds appearing red at night (something I've never seen except for during ...
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1answer
34 views

Triangulating Sol's position from another star

Let me pose this question as a hypothetical. Your ship makes a warp/jump through space. There's a malfunction. You're definitely not at your intended destination. You've warped to an unknown star, ...
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1answer
55 views

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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3answers
82 views

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 ...
1
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1answer
167 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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1answer
141 views

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 ...
1
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1answer
63 views

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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4answers
68 views

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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2answers
63 views

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 ...
2
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1answer
108 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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1answer
51 views

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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2answers
51 views

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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0answers
23 views

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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1answer
191 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
119 views

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 ...
2
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1answer
51 views

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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1answer
109 views

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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0answers
42 views

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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2answers
150 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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2answers
428 views

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?
3
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1answer
64 views

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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0answers
117 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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2answers
114 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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0answers
59 views

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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2answers
141 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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1answer
59 views

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.
3
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5answers
561 views

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 ...