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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Nuclear decay rate affected by sun and quantum randomness

If nuclear decay rate were affected by sun, then emission probabilities would be subject to sun state and its influence, so quantum randomness would depend on it, Would it still be truly random? One ...
HDE's user avatar
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8 votes
2 answers

How to create unusual sundial?

I am considering small "artsy" project. I would like to create sundial by placing gnomon on the window and painting hour lines on the window facing wall. Since this is to be placed in bedroom I am ...
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7 votes
3 answers

What frame(s) of reference are used to measure the rotation of the Sun around the galaxy ?

I can find various speeds and estimated durations listed at numerous places but none specifically describe the frame of reference. Possible options as example of kind of answer I expect. Local ...
John McNamara's user avatar
4 votes
1 answer

Are solar physics images of use to the night-time community?

I'm actually interested in cases of cross-discipline data re-use. I know that the SOHO/LASCO coronographs are used for comet finding, that solar telescopes were used to get information about Venus's ...
Joe's user avatar
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3 votes
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If 100% of the energy from the sun is reflected back into space

100% of the energy from the sun is reflected back into space, it's just shifted from a low-entropy state to a high-entropy state, and from a high frequency (ultraviolet) to a low frequency (infrared). ...
ixtmixilix's user avatar
16 votes
2 answers

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 ...
Brian Hooper's user avatar
46 votes
6 answers

Can the apparent equal size of sun and moon be explained or is this a coincidence?

Is there a possible explanation for the apparent equal size of sun and moon or is this a coincidence? (An explanation can involve something like tide-lock effects or the anthropic principle.)
Phira's user avatar
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2 votes
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Solar Cycle UV Variation

The average energy we receive from the Sun is $1,366 \ \mathrm{W/m^2}$ , and this only varies by $0.1\%$ from the activity peak to trough of its 11 year cycle. About $9\%$ of the energy comes from ...
Michael Luciuk's user avatar
3 votes
1 answer

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 ...
simon's user avatar
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13 votes
5 answers

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 ...
d4nt's user avatar
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3 answers

How does solar activity affect the ISS?

Currently the sun is launching some intense solar flares. Th article I've linked also mentions how a "coronal mass ...
Ben Griffiths's user avatar
6 votes
2 answers

Using energy from sun magnetic field

Knowing ...
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3 votes
2 answers

Producing energy from magnetic flux loops

I've simplified this down by quite a lot but as far as I understand it, magnetic fields on the Sun's surface twist together and when it gets all a bit too much they release energy. My question is why ...
jamiers's user avatar
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3 votes
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Energy of the electron-muon reaction

Lets see the reaction: $e^- \mu^- \to e^- \pi^- \nu_\mu \;\;\;\;\;\;\;\;\;\;\; {(1)}$ I suppose, that this reaction occurs as follows $e^- \mu^- \to e^- \mu^- \pi^+ \pi^- \to e^- \pi^- \nu_\mu$ Is ...
11 votes
3 answers

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 ...
Nick's user avatar
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7 votes
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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 is it and why does it work?
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