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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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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How is sun's atmosphere (corona) hotter than the surface itself? [duplicate]

Through some research online, I found out that the sun's corona is hotter than it's surface. How's that even possible?? Is the sun releasing it's heat from the surface!!! Need a complete answer.
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61 views

How does the sun rise upwards with brightening and set downwards with low fading being stationary on a spinning earth? [closed]

Can someone please apprise me with this phenomena that earth is spinning on it's own axis with 23.5 degrees tilt also rotating around the sun while sun is stationary. when sun is just rising up we can ...
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1answer
128 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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1answer
271 views

How far away from the Sun does space start to be cold?

I assume that if I stood on the sun, I would be hot. I similarly assume that if I stood about 10 feet from the sun, I would still be hot. However, if I stood in space 93 million miles away, I would be ...
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1answer
73 views

How and why do sunspots occur?

I am studying sunspot behavior, and the causes for the occurrence sunspots occur. I've come across the phrase 'local magnetic fields of the Sun'. I have no idea what that means. Can someone please ...
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2answers
127 views

Temperature of fusion in the Sun vs. fusion in controlled experiments on Earth

I recently learned that hydrogen fusion (i.e., hydrogen to helium) experiments on Earth have been successful at temperatures in excess of 100,000,000 degrees Celsius. However, I also learned that ...
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0answers
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Relation between radius of curvature and heat produced at focus when concave mirror is kept in sunlight [duplicate]

Hi I am newbie here and this is my first question so please do not mind if I don't use the correct language or anything. I want to know the relation between size of a concave mirror ( measured by ...
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2answers
108 views

Is sun a black body? [duplicate]

My teacher told me that sun is a black body but after reading at various sites whre they say that sun is not a black body but has black body radiations because it cannot absorb all radiations.
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What would happen if the Earth was in a polar orbit around the sun?

This is a question that has been bugging me for a while now, I was wondering about the effects on the Earth if it was in different orbital situations to what it is now, and one of those was what would ...
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Why is there a temperature gradient on Earth?

I was thinking about why the poles are colder and I came out with three possible explanations. 1. The atmosphere blocks light beams coming to poles The Sun is seen only slightly over the horizon ...
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1answer
59 views

Effect of radiation pressure on Earths orbit in large timescales

I have seen some posts concerning the radiation pressure exerted by the Sun on Earths surface (Force on Earth due to Sun's radiation pressure). Though it is fairly small may it have a considerable ...
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1answer
714 views

How small would the patch of sun be that delivers heat to the earth?

The sun, being a ball, projects its EM radiation and light in all directions. We earthlings only receive a light from a portion of the sun, not all of it. What size is this patch of the sun's surface ...
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1answer
63 views

How to calculate max temperature craft needs to withstand near the Sun

The Solar Probe Plus fact-sheet states that the craft will approach to the distance of 9 solar radii to the surface of the Sun (Approx 6.26e6 km) and its heat shields must withstand 1644K of heat. I ...
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1answer
50 views

What happens if an object stops orbiting the sun? [closed]

What would happen if an object (like a space ship) was to stop its orbit around the sun. would time slow down with that object (the same way time sped up for the characters in that great film ...
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1answer
69 views

What unusual effects will we observe on the non-rotating Dyson sphere with earth gravity around the Sun?

First let's place our sphere Let's assume there is a two-layer non-rotating Dyson sphere around the Sun (ignore the scale): Green is empty air. How far should the inner border of this sphere be ...
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1answer
91 views

Would an object falling on the surface of the Sun look like this? [closed]

I've been playing around with some rustic animation and then I came to simulating gravity over squishy objects, I simulated a squishy ball of unknown "squishiness" (I'm sorry I don't know a lot of ...
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3answers
2k views

How can we see the moon while it's between the Earth and the Sun? [duplicate]

I know this sounds like (and probably is) a stupid question, but I can't figure it out. As far as I know, the crescent shape of the moon is when the moon is on the sunny side of the Earth, but that ...
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1answer
285 views

Is there any metal or any material that can survive the Sun? [closed]

If we were to send a unmanned spaceship through the Sun. What material can survive?
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5answers
90 views

Static model of the Earth motion

Believe it or not, an old man I know in 2015 still negates the Earth orbital motion around the Sun. He believes the earth is rotating on itself and acknowledges this gives day and night on every ...
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2answers
121 views

Will the Sun ever get 100x powerful? If so, when?

I was doing a theoretical research regarding life on Titan. The temperature of Titan is so low, and it needed more sunlight, as a result, the Sun would require to get hotter. My question is, when will ...
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1answer
104 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 ...
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1answer
195 views

Mass loss for Fusion energy? [closed]

I am thinking how you can estimate the mass loss of the fusion energy for 1 kWh. I think you cannot use Einstein's $E=mc^2$ to calculate the mass loss in the fusion reaction of the Sun. How can ...
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2answers
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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 ...
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1answer
162 views

How much radiation does the Earth receive from the Sun's total radiation? [closed]

I was thinking how to solve this problem. $1\,\mathrm{AU}$ is roughly the distance from the Earth to the Sun, $1.4960 \times 10^{11}\,\mathrm{m}$. The radius of Earth is approximately $6.4 \times 10^{...
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Looking at the sun through heavy fog, do invisible wavelengths get through?

This morning it was particularly foggy and my son was excitedly looking at the sun through the fog, since of course he normally can't look directly at it and see the disk. I told him to stop looking ...
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How far out from the Sun is visible light still sufficient to read a book?

Recent pictures from the New Horizons spacecraft, shown below, seem to indicate that, at Pluto's distance, we are entering a twilight zone, with a distinct lack of colors, although that could be due ...
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1answer
83 views

In what ways does the sun output energy?

I'm curious about the energy output of the sun, and how it breaks down. What fraction is from EM radiation, solar wind, neutrinos, et cetera? How does energy output vary over the EM spectrum? I was ...
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2answers
189 views

Why is sunlight not violet in color?

I have a UV lamp which appears violet in color, but our own sun also emits UV rays so where does the violet go? Why does sunlight not appear violet?
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1answer
115 views

Can a baseball travel through the Sun?

A baseball moving sufficiently close to the speed of light could theoretically spend less than a nanosecond inside of the Sun in the balls frame. If a baseball were traveling close enough to the speed ...
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3answers
98 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, ...
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1answer
63 views

Will Mercury fall to the Suns core?

When the Sun enters its red giant phase, what exactly will happen to Mercury?
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2answers
153 views

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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111 views

What causes the death of the Sun?

In a previous question I learned that in each second only a miniscule portion of the total hydrogen in the Sun is converted to helium and that the number is 1/10^18 of its mass converted each second. ...
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1answer
43 views

Why is radiation under Poynting-Robertson drag anisotropic?

According to the Wikipedia article on Poynting-Robertson drag, the reason solar radiation slows an orbiting object is because the re-radiation of photons by the object is anisotropic in the frame of ...
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1answer
133 views

Where is the Hydrogen the Sun consumes?

I understand the Sun consumes 600,000,000 tons of Hydrogen each second. Where is this Hydrogen? Is all the Hydrogen the Sun will ever consume inside it or are there vast amounts of Hydrogen in space ...
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3answers
158 views

Are there more photons than nuclei within the Sun?

Are there more photons than nuclei within the Sun? Is there a good way to estimate what the ratio would be?
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1answer
169 views

Is the sum of mass of all planets in our solar system is 40% the mass of the Sun? [closed]

According to Chandrasekhar Limit,the mass of an object can not exceed than 1.4 times the mass of the sun.But according to some other theories,the sun was very large at former times and earth and ...
2
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1answer
27 views

Do trace elements in a stellar proto-cloud affect the spectrum of the resulting star?

Two quick questions regarding the origin of our Sun: Our own Sun was probably part of a much larger gas cloud and I wonder, if two distinct stars condense from a homogenous protocloud, do very slight ...
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1answer
65 views

Image formation or Diffraction?

I was watching this video on the YouTube channel Veritasium. In this episode, the host shows people paper containing holes of different shapes in the middle. So there is a paper which has a hole in ...
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2answers
48 views

What causes red skies? [duplicate]

This morning, as I was walking to work, I noticed that the skies were different. It had a reddish tint. What causes this?
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5answers
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Did the Sun form around a solid core?

When Jupiter formed I assume like the other planets it started as tiny clumps of matter that eventually came together, became gravitationally bound and then eventually captured a lot of gas. I've also ...
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1answer
394 views

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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2answers
313 views

Can the Sun's core be treated as an ideal gas?

I know that a gas behaves more like an ideal gas at higher temperature, and that is very well achieved in the Sun's core. But also low pressure is needed for a gas to behave like an ideal gas, and the ...
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2answers
38 views

Is it possible to calculate the relative abundances of elements in the sun based on its line spectrum using a common lab spectroscope?

There are many problems that I feel would hinder the process: atmospheric noise, light pollution etc. Let's assume that I bypass these problems and get an accurate emission line spectrum on the ...
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1answer
145 views

How do solar cells increase the lifespan of the Sun?

While reading "Physics of Solar Cells" by Würfel, I came across an amusing statement: An interesting aspect arises if we had to pay for solar energy, but could also get a refund for energy ...
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1answer
118 views

Calculating the Surface Temperature of the Sun with a Metallic Strip from the Surface of Earth

I am trying to calculate the surface temperature of the sun with a copper strip. I have a temperature sensor to calculate the temperature of the strip and that's it. Assuming the rate at which energy ...
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3answers
3k views

How does the heat of Sun come on Earth when there is no medium?

Sun is the most important source for life on Earth which gives sunlight and heat on Earth. But I was wondering like how does the heat of Sun come on Earth when there is no medium out there in space?
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177 views

Is sunlight truly white?

I recently purchased a book on nuclear astrophysics, with no goal of mastering the topic but merely to read in between exams and hopefully learn something, it is revealed that the sun is composed ...
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1answer
50 views

How close to the surface of the Sun would one have to be to determine an 'upright' position relative to it's surface?

As we stand upon the surface of the earth we're able to establish a relative 'up' and 'down' direction due to gravitational forces. As we leave the confines of the earths gravitational attraction ...