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 is the solar magnetic field produced?

I have been trying to understand the magnetic field creation mechanism. I know that its origin is not perfectly understood, but what is currently believed (as I know) is that the magnetic fields ...
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Temperature and latitude

Currently I read this excerpt on a school power point that stated the following: " The sun is closer to the equator than the poles. Therefore the sun’s rays have less distance to travel to the ...
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Have solar wind particles escaped the Sun's gravity or will they eventually return back?

I've read that solar wind consists of hydrogen atoms that are, near the Earth, travelling at about 450 km/s. This is only 3/4 of the Sun's escape velocity, but then the Earth is also 150 million km ...
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Black body side of the Moon

A few closely related questions regrading the Moon thermodynamics: The Moon is clearly not a black body, as it reflects a great deal of radiation incident on it. Still, it does absorb some radiation ...
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Does pressure increasing or decreasing due to temperature have an impact on the Sun Core's "Thermostat"?

Firstly, thank you for reading this post. I have a question regarding how the Sun regulates its nuclear fusion rate in its core. This is commonly known as the Sun's thermostat. This is a homework ...
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Colours of the sky if sun was blue?

What would be the colours of the sky at different points of the day if the sun was a blue star? This is assuming that our earth is at a similar distance away from the surface of the blue sun as it is ...
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How much percent of the speed of rotation of the solar surface at the equator is due to frame dragging effect? [closed]

Frame dagging effect is interesting and my particular interest is does this rotation could be compared with the law of motion of planets in a system similar to our Solar system and also can we measure ...
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Building orientation - how come both summer and winter solstice used for a facade?

I am planning to build a shed atop my terrace. I was analyzing the sun path to determine the overhang length, facade height etc, but got stuck with a conflict as below. The summer sun's location peaks ...
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Is Thermal radiation emitted by a blackbody some photons

If a blackbody absorbs all radiation and emits some due to it's heat, then is the thermal radiation actually some photons that are not in the visible region? Can there be a blackbody that emits ...
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Long temporal coherence sunlight

What is the reason that sunlight have short temporal coherence? I know everybody says that coherence length is inversely proportional to bandwidth. Does it mean that if sunlight passes through a very ...
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How do objects emit light?

I recently bumped into a question of how things emit its color. And I've gone through some articles on the internet to be now stuck between two phenomenon: reflection (I'm not sure if its called this ...
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Radial dependence of temperature of solar wind?

How does the temperature of the solar wind plasma depend upon radial distance from the Sun?
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Where do the Neutrons for fusing Hydrogen to Helium in the Sun come from?

The sun works by fusing hydrogen to helium (at the moment). While hydrogen is a single proton (I'm ignoring electrons here... not sure if they are relevant since it's probably a plasma anyway) helium ...
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Why does the "edge" of the sun appear red first?

During sunset, I have noticed many times that the Sun's outer boundary becomes red first but the middle part is yellowish by that time and then after some minutes the whole sun becomes red. Now I have ...
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Law of amount of interference between different Sun rays that fall on a distinct point on Earth?

The double slit experiment shows that rays comming from different locations can cancel each other when touching a point on a screen if they are out of fase because of their wave properties. Is the ...
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Can we witness Optical illusion in which sun appears to set in mid sea than at horizon?

I was searching for optical illusions and came across a video on youtube where sun seems to set in the mid of sea instead of setting at the horizon? Can anyone please explain how this illusion takes ...
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Lag in Direction of Earth-Sun Gravity vector

When the earth is orbiting around the sun, it experiences a force vector pulling it towards the sun, which acts as a centripetal force for its elliptical orbit. However, when the earth moves a bit ...
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How small/large can a sun/star be?

I have zero knowledge about astronomy (I often mistake it with astrology) so my question might be a bit naïve. But what are the limits for stars to be stable? I guess you can't up or downscale our ...
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In which direction do the perihelions of the planets show? Is this somehow correlated with the solar apex?

I just found a Wikipedia page that showed that almost all perihelion where at the same position (except for Mars) and I was wondering, if someone has more information /data/pictures. Thank you!
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How far should I be from my screen to get a crisp image?

I want to use a flat mirror to create a projection of the Sun. My mirror is 3 by 1.75 inches (5.25 squared inches). How far should I be from my screen to get a large crisp image?
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What volume would the mass of Earth occupy in the core of the sun?

I was just wondering if anyone had computed this. I read that the pressure in the Sun's core is 3.84 trillion psi. Obviously the mass of an Earth-sized object in the core would be millions of times ...
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What is the Hydrogen and Helium composition of the Sun in terms of their different states?

What is the Hydrogen and Helium composition of the Sun in terms of: Hydrogen: (1) molecular, (2) metallic and (3) ionized compositions? and Helium: (1) atomic, (2) metallic and (3) ionized ...
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Do sunrises and sunsets look the same in a still image?

A question that popped into my head: if I see a picture of the sun close to the horizon, in an unknown place, can I know if it was taken at sunset or sunrise? Do sunrises and sunsets look the same in ...
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Was Eratosthenes justified in his belief the earth was round? [closed]

Because I see two flaws with it, firstly he assumes the distance of the sun won't affect the angle at which light hits the pole. If the sun were far closer and far smaller, there would be a change in ...
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Are new Moons (and full Moons) more probable to happen around certain ecliptic longitudes?

The average lunar synodic month is 29.53059 days. Because of these variations in angular rate, the actual time between lunations may vary from about 29.18 to about 29.93 days. The average duration in ...
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Plage regions data

Plages are phenomena of stellar activity. Where can I find openly-accessible data of plage regions of the Sun with other parameters such as faculae region, magnetic field, etc?
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Is the nuclei and electrons distribution inside the Sun even or they form 'unbalanced distribution' layers?

Is the nuclei and electrons distribution inside the Sun even or they form 'unbalanced distribution' layers? In simple words does the difference in mass or even density between nuclei and electrons ...
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How do we know that the Sun absorbs most of the radiation that falls on it?

The sun is generally considered to be an approximate blackbody. A blackbody has to be a perfect absorber. How do we know that the sun absorbs most of the radiation that falls on it?
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What is the relationship between crescent moon and position of the sun? [duplicate]

This is a phenomenon that involves the angles between the points of a crescent moon and the apparent position of the sun. Step outdoors on a day and time when you can see the sun and a crescent ...
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How much differs the Mercury speed at perihel from its theoretical speed with no frame dragging involved?

How much differs the Mercury speed at perihel from its theoretical speed with no frame dragging involved? Can a formula of frame dragging velocity be calculated regarding the distance of a point of ...
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2 votes
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How would a vast large Solar Storm similar to the Carrington event now effect our modern society? [duplicate]

Basically I've read upon this article I found in reddit that a solar storm could potentially hit Earth and knock out our internet and fry our sensitive electronics for months. If it did happen, how ...
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Why do more massive star in the main sequence have a larger size?

My understanding is that if a star in the main sequence has a higher mass, it will produce more energy through the nuclear fusion process, hence the star is more luminous and hotter. This also implies ...
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How do I determine the exact distance from Jupiter to the Sun on a specific date?

I've recently needed to determine exactly how far Jupiter was from the Sun on April 25th 2018, when a Hubble image of Jupiter was taken. I'm a beginner in physics and Google searches lead me nowhere. ...
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Detection of day or night?

I was wondering, are there "particles" that can be detected, when one's side of earth is shined on by the sun? I understand that there are cosmic radiations present, which probably will ...
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Why is interstellar cosmic radiation more energetic than radiation from our sun?

I just watched an interesting minidoc about cosmic radiation. The video, and other resources I've read afterward, explains that the most energetic cosmic radiation comes from supernovae and black ...
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Transition from inertial to kinetic range in Solar wind turbulence

Most papers studying the turbulence in the solar wind present figures showing the power spectral density (PSD) of the magnetic field. The inertial range, with a power law index of ~ -5/3, is followed ...
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Weight dependency on the location on Earth relative to Sun

In this post a theoretical physicist says that one will weigh less at the point on the Earth closest to the Sun due to the Sun's gravity, which makes sense to me. But he also says that one will weigh ...
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How do photons from the sun make the skin feel warmer?

I know how conduction makes the skin warmer: if a hot metal bar is kept in contact with my skin, the high energy molecules of the bar make the molecules of my skin vibrate. That's why I feel warmer. ...
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What should be the temperature in the star core center for helium to not be stable so only fermion soup is present?

What should be the temperature in the star core center for helium to not be stable so only fermion soup is present? Of course, then there should be a distance from that center for fusion to be ...
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Harmful Radiation When a Thinly-Veiled but Evident Sun is Directly Viewed Under Haze or Cloud Cover

When it is hazy or overcast with many thin fast-moving clouds, the sun sometimes appears faintly though the cover---making it possible to be observed without any discomfort. In fact, one could easily ...
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4 votes
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When Sun was forming and before nuclear reactions inside the core what should have been its surface temperature?

When the Sun was forming and before all the nuclear reactions started inside its core, what should have been its surface temperature (only due to gas friction)?
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How can a gamma ray conserve its momentum while travelling from the center towards the sun's surface?

How can a gamma ray can conserve its momentum while travelling from the center towards the surface of the sun? Shouldn't it lose most of its momentum while scattering from very lite hydrogen and ...
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When elements inside the Sun form plasma is there any stratification as densities of different cores are practicaly same?

When elements inside the Sun form plasma is there any stratification as densities of different cores are practicaly same?Where do electrons accumulate? I pressume it may depend on electron to core ...
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Can the amount of heavier elements in the Sun's core be approximated?

Can the amount of heavy and other types of elements as impurities inside the Sun's core be approximated? If these elements are present, do they disturb the process of hydrogen fusion, since they ...
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Are feasible facilities for production of hydrogen and oxygen from water using only solar energy? [closed]

Are feasible facilities for production of hydrogen and oxygen from water using only solar energy? Should using Hydrogen as a source of energy be uncomparably more enviroment friendly than using oil?
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How much of the suns radiation is infrared from compression heat, not fusion?

Preface: Im a college level dropout, please dont stomp on my ignorance too hard. As mass falls into a gravity well, it compresses and heats up. Even if fusion didnt exist/occur, in a body as large as ...
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Why doesn' t the sky look blue from outer space? [duplicate]

The sky looks blue because blue sunlight is scattered all over the atmosphere. Doesn't the same take place in the other direction? From Earth to the sky? So the atmosphere would look blue in outer ...
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How big is the Lorentz force on the Sun?

Inside the Sun there has to be a net current giving rise to the Sun's magnetic field. Because the Sun orbits the core of the Milky Way with considerable speed (about 0.1% the speed of light) the ...
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Would a human body flying into the sun extend or decrease the time the sun is undergoing fusion? [duplicate]

Obviously 1 human body is... nothing compared to the sun, so if the question is easier to answer with 1 million, 1 billion, the entire human population that has passed away in history... the amount ...
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Why the 'low' part of the sky looks lite blue?

When looking on the sky its lower part looks lite blue instead blue like the rest of the sky. Why is it so?
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