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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Why is Sun's energy entropy low on Earth?

Warning I don't have a physics background, having said that I was recently looking into the sun's radiation energy entropy and I had a couple of questions. So it is said that we can utilize the energy ...
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Why the Sun has a higher temperature than humans?

Why the Sun has a higher temperature than humans if the energy/gramme of matter ratio of humans is greater than that of the Sun?
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What would happen if the sun became the size of the earth? [closed]

Imagine that a sudden force crushed the Sun from its current size down to the size of the earth,held it at that size for a few moments and then disappeared. What'd happen? I haven't done any of the ...
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Why sun revolve around the sun ? Why cant it just rotate ? ( gravitas attraction force makes it revolve , how?) [closed]

Why the revolution ? How General relativity theory explains it
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Using helioseismology what are the equations astrophysicists use to determine the age of the Sun?

Astrophysicists talk about solar models when determining parameters of the Sun. But these models must be built from equations. When explaining to the general public what these equations are would be ...
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Is it possible to predict the appearance of auroras?

Yesterday I saw online a lot of people seeing auroras both in the North and in the South of the globe. Unfortunately, I wasn't one of these people, and this got me curious about how much we can ...
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What's the proper way to calculate neap low tide and high tide tide-raising forces?

My coursemates (and maybe, through them, my professor) insist that to calculate the neap low-tide tide-raising forces, I should take $F=\frac{GMa}{d^3}$ for a point on the earth $90°$ from the nearest ...
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Sudden drop in temperature in Sun convective zone

In the solar temperature graph, why does the temperature drop suddenly in the convective zone? Is it because some energy is needed for ionisation?
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Does sunlight have a modulation frequency?

By frequency, I don't mean electromagnetic frequency, I mean modulation frequency. For example, I can put a PWM square wave on an LED at some frequency, which I can detect with a photodiode and a ...
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The speed of an impulse transmitted along a string

A supernova explosion on the far side of the Sun ejects a mass with approximately the same mass of the Sun directly at the back side of the Sun. If this ejected mass is travelling arbitrarily close to ...
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What creates the Global Dipole Magnetic Field in the Sun?

I understand that the Sun undergoes convection and with rotation, the convective cells have a helical motion because of the Coriolis Force. My confusion comes from the fact that via the right-hand ...
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Luminosity and absolute magnitude relationship

Context : an exercise gives the temperature, mass, distance and apparent magnitude of Sirius B and asks to calculate its density. One key step of the calculation is to get the luminosity from the ...
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Fusion in the sun for 4 hydrogen to Helium-4. How is the energy produced

So please correct me if I am wrong but: First 2 proton’s (each with an electron) fuse together, The mass stays the same so no energy is produced? Then 1 of the protons turns into a neutron with a ...
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Brightness of the light source at twilight computation

I would like to determine the brightness of the light source at twilight based upon its apparent magnitude. In the question here: What are the average wavelengths and brightnesses of sunlight across ...
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How do we know that the Sun is 71% Hydrogen by mass from emission/absorption spectra?

In my Intro to Astronomy ("intro" is very important, please keep responses as simple as possible) course, we're currently learning about light and electron orbitals and such, and I came ...
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Why the Sun does not shoot relativistic jets?

I saw the features of the Sun here and it has almost everything include nanojets and CME but not relativistic jets. Isn't the Sun magnetically active so why isn't it capable of shooting out ...
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What is the albedo of our Sun?

I think the Sun is the closest to a perfect natural black body we can get in the Solar System, if so then what happens to the light if I point a laser pointer at the Sun?
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Where is there visible light inside the Sun?

The solar core has a temperature of 15 million K, but the visible color temperature is only between 1000 K and 10000 K. Also, the plasma is very dense at the core, so it won't be able to travel there. ...
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Estimate distance of a halogen lamp to simulate sun

I'd like to simulate sun effects on a material affected by UV and IR. Actually is winter and I'll need to wait 6 months to have maximum sun intensity and be able to expose it to direct sun. I've a ...
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What is the difference between granulatiion, mesogranulation, supergranulation and giant cells in sun's photosphere?

Help me understand the differences between granulation, mesogranulation, supergranulation, and giant cells and at what depth they are created.
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Does the Earth's magnetic field lag behind the Earth as Earth orbits the sun?

I imagine that when the earth orbits the sun, the earth's magnetic field is also subject to the sun's gravity, since photons and light are subject to gravity. As a result, the magnetic field does not ...
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How fast do I have to fly vertically up to pause sunset?

I'm standing on the famous Laguna Beach in southern Los Angeles to watch the sunset on December 18th (33.541679°N 117.777214°W, 0m elevation, 16:44 PST). Now, from my perspective at the shore, the sun'...
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How much radiation on the surface of the moon during a Coronal Mass Ejection (CME)?

I'm writing a book set on the moon. A Coronal Mass Ejection (CME) as large as the Carrington Event hits it. Three astronauts are caught out during an EVA. They will cover their rover in regolith to ...
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How is volume defined and measured in nuclear physics, in particular regarding the Sun’s core? [closed]

The Sun’s core is, from the micro/quantum perspective (from what I've read) the constantly moving phenomena of nuclear fusion (as the Earth is mostly the constantly moving phenomena of stable atoms ...
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Nuclear fission in the Sun

The Sun's energy comes primarily from fusion of light elements in its core. It is estimated that a very small fraction of mass of the Sun (~$10^{-12}$ times the abundance of hydrogen) is uranium (both ...
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Solar neutrino deficit, 1/3 or 1/2?

The puzzle of the missing solar neutrinos is supposedly solved by neutrino oscillations. I understand the mechanism, but there is still one point which I find unclear. For the energy range and ...
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Which gravitational differences we would feel if the sun disappeared?

I would like to start by stating that I'm not a physicist, I'm purely a curious individual. I've been speculating about the differences the loss of the sun's gravitational field would have on us and ...
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How to estimate the Kolmogorov scale of the plasma in solar corona?

I would like to estimate the order of Kolmogorov scale $$l_k = \left( \frac{\nu^3}{\epsilon_d}\right)^{1/4}$$ of the plasma in solar corona, so I need to determine the viscosity $\nu$ and ...
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How is there so much ionized hydrogen in the sun?

To my understanding, the sun contains large amounts of ionized hydrogen compared to the amount of hydrogen in the first excited state. I am curious about the explanation, at the quantum scale, for how ...
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How fast is the naked-eye visible transition of a main sequence star to a giant? [duplicate]

I know the evolution of a main sequence star to a giant is a process that takes millions and millions of years, but how fast is the VISIBLE change? Basically, will our sun, for example, slowly grow to ...
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Is Sun not the biggest source of energy to us?

Probably in my 5th or 6th grade, I learnt in my science classes that sun is the biggest source of energy to us. However, I was watching this youtube video according to whom the energy of earth is ...
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Why do sun emit light of different frequencies? [duplicate]

The sun emits white light, which is a mixture of light from all frequencies. Instead, it should have emitted a beam of light of the same frequency, as the source is the same? So, can you please ...
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Why doesn't the sunlight make noises on home satellite dishes?

One of my friends asked me a question to which I could not find a clear answer. We know that the sunlight spectrum includes the entire wave frequencies including those (of the order of 1 GHz) that our ...
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Improved estimate of density of free neutrons in solar core

In an answer to this question: Free neutrons in the sun's core? I made a very rough attempt to estimate the density of free neutrons in the solar core. There is some non-zero rate for production ...
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Why is the Sun’s emission spectrum shaped like this?

The Sun emits more at $450-600 \,\rm{nm}$ than a black body of the same effective temperature would, it also emits far less UV. I’ve heard this is due, in part, to the fact that the Sun doesn’t have a ...
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How do protons fuse in the sun?

I know that Nucelar fusion in the sun requires quantum tunneling to occur, as otherwise the Sun's core wouldn't be hot enough to overcome the Fusion barrier. However while the 2nd and further stage of ...
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How hot would the sun have to be to work without quantum tunnelling

I know that the Nuclear fusion in the sun would not work without quantum tunnelling, as the nuclei wouldn’t ever have enough energy to overcome the potential barrier. So how hot would the sun have to ...
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What machine learning technique can help generate spectrum line profiles?

I'm trying to work with Calcium-K line profiles from the Sun. Image for reference. Please ignore the labels on the image and note that my profiles are not in image format (more info below). I have ...
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Can the four Seasons of planet Earth be defined in terms of Energy? [closed]

Can the four Seasons of planet Earth be defined in terms of Energy? The definition of Energy gotten from Google is: ability to do work, which is the ability to exert a force causing displacement of ...
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Is Earth's magnetic moment vector oriented parallel or antiparallel to the sun's magnetic moment?

Just curious how these two magnets are spatially related to? And in case there is no any special preferred particular orientation, what is anyway their spatial orientation relation (relative angles)? ...
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Why is the solar spectrum at the surface of the Earth strongest in the visible light range? [duplicate]

I watched a CrashCourse video saying that nuclear fusion of $\rm H$ to $\rm He$ in the sun radiates mostly gamma rays. Then why are the lights that come to Earth comprise mainly of IR & visible ...
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Which way does current flow in coronal loops and filaments?

My understanding is this: the Solar surface becomes speckled with more sunspots near Solar maximum, and these spots tend to form groupings known as active regions; each spot is associated with a given ...
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Do Solar Eruptions happen in more than one rotational "layer" in Sun's Differential Rotation? [closed]

Do Solar Eruption occupy more than one rotational layers? Is it possible to confirm this just for most outer layers? Does the number of layers occupied by those eruptions when they happen tell us ...
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Can I find the surface temperature of the Sun using a spectrometer?

So I have a high school physics project and I essentially have this experiment idea where I use spectroscopy to find the surface temperature of the sun. Now I'm essentially going to assume the Sun is ...
1 vote
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Why is the top of the mountain cooler than the surface? [duplicate]

Why is the top of the mountain cooler than the surface when the mountains are actually more closer to the sun and hence should be hotter?
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Why doesn't sun go all the way to the horizon during sunset?

This is a very silly question and I really don't know the answer to it but curious to know. Everytime I see the pics of suset on beaches the sun appear to go all the way down to the surface of the ...
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Could humanity buy more time with climate change by blocking out some direct rays of the Sun with an artificial (partial) eclipse?

Imagine the Earth faced the imminent crisis from climate change as the planet warmed by 1.5C. As a last ditch attempt to buy more time, humanity finally decided to do whatever it takes to stop the ...
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Should blue & white stars appear red and inflated while observed on the lower part of the night sky for the similar reason as the Sun during sunset?

Should blue and white stars appear red and inflated while observed on the lower part of the night sky for the fairly same reason as the sunlight during sunset? As these stars emit blue light ...
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How to identify the composition of sun if it is treated like a blackbody? [duplicate]

The sun is usually assumed to be approximately very close to a blackbody, but using spectroscopy it is concluded that the sun is made up of Hydrogen and Helium because the lines corresponding to those ...
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Why do we not see Sun red in daytime? [duplicate]

I have had this question strike to me as when thinking about the reddish colour of sun during sunsets which is happening through rayleigh scattering , the highly energetic wavelength of colours are ...
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