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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Inclination of planets

What is the inclination of each planet with the equator of the Sun? Doesn't this have a relationship with the eccentricity of the planet's orbit?
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433 views

Are we feeling the sun's heat?

If I may summarize something I told a friend in a pub... "We don't get heat from the sun at all. Heat requires matter to move through and there's too much vacuum between the sun and us for any heat ...
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65 views

Explanation for strange atmospheric phenomenon

OK, I've seen this strange thing in the sky sometimes. Not all that often, but sometimes. It actually happened tonight. On most nights, at say 9 P.M. it is dark. There might be stars, moon, etc.,...
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248 views

In the calculation of sunrise, where do the magic numbers come from?

In this question about how to calculate sunrise, there is a link to a page that describes a algorithm to calculate sunrise sunset. But when I start to follow the instructions I find that there is a ...
4
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1answer
75 views

Desynchronised pixels in images of the Sun?

NASA published this wonderfull video of Sun from SDO: https://www.youtube.com/watch?v=GSVv40M2aks And it occurred interesting question: Sun is very big sphere. Its so big that it took light 4,6 ...
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2answers
1k views

What is the Sun's core made of?

The obvious answer is hydrogen and helium plasma but the nuclear fusion can also create heavier elements. Are these heavier elements a significant portion of the core? Do the heavier elements "sink" ...
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1k views

How do you estimate colour temperature based on the position of the sun in the sky?

I'd like to estimate the colour-temperature of sunlight (as applied in photography) based on the position of the sun in the sky for a mobile phone app I'm working on (app link from a more appropriate ...
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1answer
91 views

What is the total matter equivalent of the Sun's output per year?

Say we can collect all the energy from the sun's output and all the particles from the solar wind. If we had an energy to mass converter and turned everything into say, carbon, how many kilograms of ...
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3answers
78 views

Solar plants and energy conservation

I'd like to apologise if this question is stupid or if it was asked ten thousand times - I haven't found an answer to it. Quite possibly due to mediocre English or abominable knowledge of physics. So,...
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5answers
4k views

What makes Sun's light travel as parallel beams towards earth?

Sun's light appear to travel as parallel beams towards earth $_1$. Sun produces electromagnetic radiations through pp chain and other reactions in Photosphere $_2$. I don't see whether these ...
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2answers
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Why do sunbeams diverge even though the sun is much more than a few kilometers away?

Consider this picture of sun beams streaming onto the valley through the clouds. Given that the valley is only (at a guess) 3km wide, with simple trigonometry and the angles of the beams, this ...
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2answers
90 views

Sun: When its closest and when its farther away?

If the sun is closest to the North American Hemisphere in the winter than it is in the summer, why doesn't our faces and hands tan and/or blister quicker? Please provide two hyperlink sources with ...
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5answers
2k views

Why does heat lose its energy as we get further away?

Why does heat lose its energy dramatically as I move back? Say I have a fire around 0.5 meters in front of me, I can clearly feel the heat, however, as I move even very slightly back, say 1 meter ...
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1answer
515 views

Nuclear fusion - Hydrogen isotopes

What is the isotope composition of hydrogen atoms in the sun? Are the ratios of protium:deuterium:tritium similar to those we find on earth? What does the nuclear fusion of hydrogen atoms in the sun ...
6
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2answers
163 views

How does the Sun's magnetic field continue to exist at such high temperatures?

The temperature at the surface of the Sun is apparently well above 5000 C; I'm assuming the layers beneath the surface may be even hotter. At school, we learned that heating a metal beyond a certain ...
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1answer
152 views

What does a sample of the Sun look like? Does it look like fire or gas?

Suppose that in the future a highly resistant spacecraft went to the Sun and collected three samples of the Sun: one from its surface, one from its core, and one midway. The three samples were put ...
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2answers
214 views

Solar spectrum units

Why is intensity $I$ on a graph of the solar spectrum always showed in units of $[\mathrm{W/m^2/nm}]$ instead of simply $[\mathrm{W/m^2}]$? (The y-axis on the graph.) It is apparently shown as ...
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1answer
85 views

Temperature of the surface of the sun? [closed]

I recently had an exam question that asked for the temperature at the surface of the sun. The question is The equation I believe you have to use is The Q/t is the radiant power produced by the ...
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38 views

Different ways of converting solar energy to other forms of energy

Okay so after receiving our Physics papers today I decided to tell the teacher why I lost marks on the last question: "Mention the energy conversions undergone here Sun --> Coal-fired boiler --> ...
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5answers
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4
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127 views

Stellar Activity Cycle versus Metallicity

Our Sun exhibits sunspot max/mins on about a 11 year period. It's a G2 spectral class on the HR Diagram. We know that some stars exhibit "starspot" cycles of various intensities and periods. These ...
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8answers
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Why does the Sun always rise in the East?

Why does the Sun always rise in the East? Earth is rotating on its own axis & also revolves around the Sun, then how come the Sun always rises in the East?
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3answers
640 views

Why can we see white objects as white under the sun if the sunlight is yellow?

I get that the sun is producing white light which is scattered threw our atmosphere so that the light of the sun reaching our eyes is yellow. So how come if I look to a piece of white paper under ...
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2answers
244 views

Why does a photon take less than a week to come out of the convection zone of the sun?

Sun consists of three parts: Radiation zone, Convection zone, Photosphere . When photon is formed at the core, it has high energy equivalent to $\gamma$ ray. When it crosses the radiation zone, it ...
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2answers
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What causes the dimensions of a star increase when its hydrogen fuel is exhausted?

What causes the dimensions of a star increase when its hydrogen fuel is exhausted? For example, the Sun is expected to increase its radius 250 times. What causes this if its temperature is expected to ...
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1answer
557 views

Calculating the Sun's emitted power in a wavelength range?

Is there an equation that describes the Sun's emitted power on the surface [in $\frac{W}{m^2}$] over a selected wavelength range (from $\lambda_1$ to $\lambda_2$) ? I am guessing this can be ...
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1answer
161 views

What would a normal thermometer read at the Sun's photosphere?

I was reading about the Earth's Thermosphere, and I quote this: "The highly diluted gas in this layer can reach 2,500 °C (4,530 °F) during the day. Even though the temperature is so high, one would ...
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2answers
618 views

Calculating the time of dawn

Knowing that astronomical twilight (i.e. astronomical dawn) is when the sun is 18 degrees below the horizon, I am calculating the astronomical twilight time this way: ...
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1answer
140 views

Nuclear fusion and the Sun [closed]

I am working on a science project on the Sun. I have found that in order for nuclear fusion to work, it needs both helium 3 and 4. Why can't nuclear fusion be done with just helium 4? How can we ...
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4answers
462 views

What is the actual energy content of the Sun?

Beside the energy released by nuclear fusion in the core, the Sun is a hot plasma of hydrogen and helium ranging from thousands to million of degrees. So how does that translate into energy ? I have ...
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2answers
11k views

How close can spaceship get to the Sun

If you want to fly a spaceship with human passengers as close to the Sun as possible, then what effects would the spaceship have to be designed to counteract in order to keep the passengers alive and ...
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0answers
120 views

Determining rotational period of sun using sunspots

I know that at the equator at 0 degrees latitude , you could track a sunspot and then use T=2pi/w and w=∆theta/∆t to work out the period the equator rotates, but how would you do it for, say, sunspots/...
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1answer
483 views

How are we sure a star is hot the whole way through?

Just an intuitive feeling that the surface of stars is extremely hot but under the surface all types of different atmospheres could exist and so the motion of energy could move through a star like xyz ...
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1answer
136 views

Solar granulation pictures showing a wonderous spatial resolution

Recently, I came across spectacular pictures of solar granulation like this: (source) The photograph is impressive because it has a resolution of less than 0.1 arc seconds, which corresponds to ...
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1answer
112 views

Is there a way to tell what centile of the overall sample a star's mass is in?

One hears that hyper-giant stars like Eta-carinae represent the upper bound on stellar mass at about 130 solar masses. At the lower end there are red dwarfs with as little as 0.075 solar mass. You ...
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1answer
83 views

What's wrong with this temperature-in-space calculation?

I'm trying to calculate the steady-state temperature of a body in space, but my numbers are coming up much too small. For example, for a 1-meter cube, I'm getting a temperature of 194 K (or -81 C). ...
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1answer
47 views

Sunspots and brightness

I tried to look up some facts regarding sunspots and its relation between the brightness of the sun, only to find information that are intriguing yet not what I am looking for. My understanding is ...
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82 views

What is the composition of the universe's population of neutrinos?

I believe earth-based detectors measure mainly solar neutrinos, which have energies on the MeV scale of nuclear physics, are directed from the sun, and have flavors determined by the sun's nuclear ...
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2answers
500 views

If a photon has no mass, how can it be attracted by the Sun?

I read that the photon doesn't have mass, but my teacher says that the photon has mass because the sun can attract it (like in the experiments to prove the theory of relativity). I think that there ...
95
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8answers
14k views

Why does the Sun's (or other stars') nuclear reaction not use up all its “fuel” immediately?

The temperature and pressure everywhere inside the Sun reach the critical point to start nuclear reactions - there is no reason for it to take such a long time to complete the reaction process. Just ...
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4answers
5k views

What cosmic event would cause Sun rising from the west?

I'm wondering what kind of astronomical or geological events would cause the reversal of Earth's rotation. For instance, Is a meteorite passing very close to Earth able to reverse its rotation? Can ...
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3answers
383 views

How would normal matter behave under conditions found in the core of the sun?

Considering how low the power density is at the sun's core, I seem not to be able to expect what would happen to matter in case it was thrown inside the sun's core. For example, let's assume an Earth-...
3
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1answer
905 views

live Kp index data

I need to create an online service displaying latest Kp index. Where I can take the data? The data should be in machine-readable format, i.e. text files, XML, or CGI gateways, for instance. No ...
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1answer
69 views

Dark Matter as possible an explanation for Coronal Heating

It's my understanding that the mechanism behind Coronal Heating - why the Corona is so much hotter (> 1,000,000 K) than the surface of the Sun (6,000 K), and the mechanism by which the energy gets ...
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2answers
142 views

Function to fit solar radiation data

I have ground-level radiation data of solar incoming radiation from a radiometer (cosine collector) measured along the day. In the following plot you can see PAR irradiance (ie visible light) in Watts ...
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2answers
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Are there Higgs bosons in the Sun?

To find the Higgs boson, we had to build the biggest machine mankind has ever built: the LHC with a collision energy of up to 14 TeV. Inside the sun there is a huge pressure and temperature, but is ...
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2answers
6k views

Why is the sun brighter in Australia compared to parts of Asia?

Background: I've lived in Philippines for several years, and visited other parts of Asia occasionally (Singapore, Indonesia, Hongkong). I just moved to Western Australia a few months ago and I ...
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2answers
1k views

Why does the sky suddenly look gray through this window?

I am looking to the windowed roof of my building, and I notice that the sky, which has few white clouds, sometimes looks completely gray, as if there was a huge cover of gray clouds, but there are not....
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231 views

Earth's Temperature

I have a question regarding earth's temperature... How come the average temperature in the middle east (Israel, Saudi Arabia, Sudan or lower) is always so much significantly higher than in Europe (...
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385 views

How are the northern lights produced?

Although I've never seen it myself, I hear the northern lights are a sight to be seen! I know they're related to the Earth's magnetic field but I don't know much more about them. What is the physical ...