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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Is Earth's orbit around the Sun affected by the ~8 minutes light delay?

Gravitational change occurs at the speed of light. As a consequence, we experience on Earth the gravitational attraction of the Sun based on its position relative to us ~8 minutes ago. How does this ...
2
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1answer
68 views

Gravitational force between Earth and Sun is decreasing

According to one of the most famous equations in physics, i.e. $E=mc^2$, the mass of the Sun is decreasing as it emits energy. So there must be some kind of disturbance in planetary orbits, and if ...
26
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5answers
4k views

How do those T-shirts that change color in the sun work?

When I was a kid, I asked my dad about them and he said (not in so many words) that it was because sunlight and artificial light have different spectrums and they picked colors that reflect only the ...
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3answers
98 views

Flat-Earthers Claim: Crepuscular Rays $\implies$ the Sun is Close [closed]

I have been trying for a couple of days to come up with a nice illustration of why crepuscular rays are not suggesting that the sun must be close to the earth, as flat-earthers claim. I made the ...
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3answers
2k views

Why does the light side of the moon appear not to line up correctly with the evening sun?

I live at roughly $(52.4^\circ,-2.1^\circ)$. On sunny evenings I've often looked at the Moon and the Sun and noticed that the light part of the Moon does not appear to line up with the Sun. For ...
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5answers
4k views

Why is the Sun called an “average star”?

This is a statement (presumably in mass, longevity, energy output) many people that I've met have heard in school, and it is known in pop culture. However, according to Wikipedia, about 75% of the ...
52
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3answers
5k views

Why does the sun have to be nearly fully covered to notice any darkening in an eclipse?

I was looking at eclipse footage and I noticed that it doesn't get any noticeably darker until the very end when it suddenly all the light is gone. As the moon blocks out the Sun, I would expect that ...
2
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3answers
87 views

Measuring Rotation of Sun

If the sun had a uniform surface (i.e., if there were no sunspots to look at), is there a practical way to measure its rotation? In other words, if some external force flipped the sun's spin suddenly,...
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2answers
4k views

Why does the Sun “shine brighter” some days?

Today, the Sun seems extremely bright; more dazzling than usual, and even the roads seem to be brighter so it's not just when you look up in the sky. Is more light actually getting through (perhaps ...
4
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0answers
55 views

Path of photon from Sun to earth unaltered?

I got into a discussion regarding the light from the Sun that reaches the Earth and whether it maintains the same path from the moment it was emitted to the point it is processed by our eyes. My ...
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3answers
94 views

Explanation for the spectrum of the sun?

My Question is, why exactely does the intensity vanish below 240 nm ? If i look at the plank's law, obviously the intensity for $\lambda \rightarrow 0$ and $\lambda \rightarrow \infty$ will vanish, ...
3
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3answers
49 views

Can we observe solar p-p fusion reaction somehow on Earth?

What are the properties of proton+proton fusion reaction $p + p → 2H + e^+ + ν_e + 0.42 MeV$ making it hard to replicate on Earth? If we aim beam of protons to a can of water, won't we observe ...
3
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1answer
2k views

How to determine day/night based on latitude, longitude and a date/time?

Is there a simple method of determining, given a UTC date/time, whether it is day or night at a given lat/long coordinate? I am currently using a formula based on a Sunrise/Sunset Algorithm from the ...
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0answers
13 views

Generic Rayleigh effect experiment - nothing happens for water

On youtube, a bunch of Rayleigh scattering experiments (e.g this one are set up with some compound being added to water in order to invoke the effect. Why is there no Rayleigh effect for "pure" water?...
35
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4answers
15k views

Why is a new moon not the same as a solar eclipse?

Forgive the elementary nature of this question: Because a new moon occurs when the moon is positioned between the earth and sun, doesn't this also mean that somewhere on the Earth, a solar eclipse (...
3
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2answers
52 views

Possible Safe Areas In a Solar Flare

Which part of the earth would be the safest in case of the major solar flare? Will it be near equator or something like that?
5
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2answers
45 views

Does the solar wind correspond to a net electrical current?

The solar wind is a stream of ions emitted from the sun. Are there more positive than negative charges released? That is, is there any imbalance in the charge emitted from the sun in the solar wind?
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1answer
65 views

The sun glows bright white, but what color of light does it reflect?

Basically if you take a gray iron bar, and heat it red hot, it would still reflect a dullish white light, even though all you could see is the red light it emits as radiation. In fact if you watch ...
0
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1answer
73 views

As planets orbit around the Sun, does the force of gravity due to the Sun remain constant?

I know that the force of gravity is: $$F = GMm/R^2$$ Where $G$ is gravitational constant, $M$ is mass of sun, $m$ is mass of the orbiting planet and $R$ is the distance between the center of their ...
5
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2answers
2k views

Why does the Sun turn red near sunset?

At daytime the Sun's light is yellowish if not near white. Why when the Sun starts to go down that it's light turn more red. I don't think the earth's rotation is so rapid to cause a red shift. Why ...
0
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1answer
61 views

Gravity Sun Earth Moon [duplicate]

The gravitational pull the Sun has on the Moon is roughly two times greater than the pull the Earth has on the Moon. If this is the case, why does the Sun's gravity not pull the Moon away from the ...
16
votes
4answers
10k views

How Earth protected from the gamma rays generated by Sun?

Sun is generating energy by nuclear fusion. And nuclear fusion will emit energy in the form of gamma rays. Normally earth's ozone filtering the Ultraviolet radiation. And magnetic fields of earth ...
1
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2answers
108 views

Why doesn't sunlight flicker like candle or flame torch?

Why sunlight appears constant and stable like sun is a bulb? If the surface of the sun and processes going in it are not completely uniform why don't we notice any flickering or non- uniformity in ...
4
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1answer
44 views

Measuring the size of the core of the sun with multiple neutrino detectors

Back in 1998, researchers at the Super-Kamiokande neutrino detector released this image: of the sun using their neutrino detector using approximately 500 days of data. This picture covered 90x90 ...
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3answers
76 views

Why doesn't the earth collide with the sun in 64 years?

According to another answer on this site, the time it takes for two bodies in space to collide can be computed with the following formula: $$\frac{\pi}{2\sqrt{2}}\frac{r_0^{3/2}}{\sqrt{G(M+m)}}$$ ...
0
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1answer
101 views

How long is a 'sun year'?

I know that a 'sun day' is the time that a sun spot takes to orbit one time across the suns surface (25-30 days dependent on location I think) and what is actually defined as a 'sun year' is how long ...
3
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3answers
49 views

Does visible light heat things up?

During a sunny day the walls of my house warm up (no surprise). My question: how much of this warming up (if any) comes from visible light? I associate infrared with thermal energy. If my house was ...
5
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1answer
1k views

What is the electric charge of the Sun and its corona?

What is the net electric charge (in magnitude and sign) of the Sun and its corona?
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2answers
33 views

Diminishing solar temperature and its effects on earth

This is a hypothetical question; considering both the earth and the sun as black bodies. If the temperature of the sun decreased N times, what would be the effect on the radiation intensity received ...
4
votes
1answer
70 views

How far has Earth moved from its birth orbit?

It says earth is almost as old as 1/3 of the universe's age which would mean 4.5 billion years . So how far has earth moved towards or away from the sun in these 4.5 billion years? Now perfect ...
14
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2answers
1k views

Is the length of the day increasing?

In Frontiers of Astronomy, Fred Hoyle advanced an idea from E.E.R.Holmberg that although the Earth's day was originally much shorter than it is now, and has lengthened owing to tidal friction, that ...
0
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3answers
110 views

Create a laser from sun light

I have read on wikipedia the basic theory behind laser. A photon passes through an excited electron which then produces the exact same photon. Light is bounced off mirrors to create more photons. Is ...
9
votes
4answers
2k views

How many percent of the visible light reaching the Earth are from other stars than the Sun?

How many percent of the whole visible light reaching the Earth are from other stars than the Sun? Is it maybe 0,5 - 1% or is my guess already too much? I am interested mainly in visible light, but ...
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0answers
94 views

How to derive equation for time it takes photons to diffuse through the Sun

I am wanting to use the Rosseland radiative heat flux equation to find the time it takes for photons to diffuse through the sun. The answer I am wanting to derive is: $$\tau_D~\frac{\rho \bar C_p R^...
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0answers
14 views

Color Temperature Variation of Sunlight

I want to know what is the Variation of the color temperature in Kelvin of Sunlight as viewed from the earth from Sunrise to Brightday to Noon to Sunset. Will there be any change in the color ...
0
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0answers
17 views

Experiments on the melting of snow?

When snow melts there are three main variables: the temperature of the air, the altitude of the sun, and the distance of the sun from the earth (which changes because the earth moves in an ellipse ...
3
votes
1answer
112 views

What causes the differential rotation of the Sun?

I have read the explanation in Wikipedia, but the problem is that because I'm a beginner in physics, I don't quite understand what more than half of the words mean! Here is the explanation from ...
49
votes
4answers
4k views

Why does moonlight have a lower color temperature?

Moonlight has a color temperature of 4100K, while sunlight has a higher color temperature of more than 5000K. But objects illuminated by moonlight don't look yellower to the eye. They look bluer. ...
4
votes
1answer
55 views

How much of Ultraviolet is cut out when Sun moves to the Horizon?

EDIT: Original question was whether or not we need to wear sunglasses when Sun is at the horizon. But it was confusing to many users whether it is on-topic or not. So the details are adjusted. From ...
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1answer
51 views

Spacetime Mercury vs Earth

What is the time dilatation of the planet Mercury compared to 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
38 views

Lead shielding very close to the Sun

I understand that eventually lead would melt when it nears the sun. In a liquid state how effective would lead be in blocking radiation? Would it still be as effective as solid state of lead? What ...
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1answer
79 views

What do sun spots look like under the surface of the Sun? [closed]

Do sun spots float like oil, float around like a lava lamp, is it more like the tip of an ice burg or what?
1
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1answer
60 views

Does solar eclipse have impact over increase of earth's temperature?

Does a solar eclipse have an impact on global temperature? Wired theory : When I jump, does the Earth recoil? Yes, the Earth has to move in some way for momentum to be conserved. However, since ...
9
votes
2answers
1k views

Why don't we see solar and lunar eclipses often?

Since we see the new moon at least once in a month when the Moon gets in between of the Sun and the Earth during the evening ( and as far as I know if this happens during the day, you'll get to see a ...
0
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0answers
26 views

Energy potential of a cold sink inside the sun

An answer in this question discusses using a fusion engine in a theoretical spaceship within a star. http://worldbuilding.stackexchange.com/questions/37589/what-are-the-consequences-of-literal-...
5
votes
1answer
2k views

Formula for getting time of sunrise at a particular location?

Is there a formula that can get sunrise at a particular latitude and longitude (and elevation from sea level)? If so, what it is? (Why does it work?)
2
votes
1answer
229 views

Is there anything special about the Sun's photosphere in terms of density?

The Earth has a definite boundary between rocky/ watery surface and gaseous atmosphere. The same cannot be said of the sun. Even though the photosphere gives an apparent "edge" to the sun via the ...
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2answers
57 views

Can solar flares affect gravity?

Can a large eruption of solar flares on our sun change the effects of its gravity ever so slightly, and is it possible to measure these changes with the equipment we have today.
8
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1answer
244 views

Why is my shadow deformed and not the shadow of the ceiling? [duplicate]

Look at these two photos of my shadow from sunlight. Case 1: My shadow is separated from the shadow of the ceiling and my head is round. Case 2: But when I walk a little more and the shadow of my ...