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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3
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1answer
283 views

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). ...
13
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2answers
919 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 ...
25
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6answers
4k views

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.)
2
votes
1answer
126 views

Solar Cycle UV Variation

The average energy we receive from the Sun is 1,366 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 wavelengths less than ...
3
votes
1answer
668 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 ...
6
votes
3answers
931 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,-2.1. On a 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 example, at about ...
0
votes
3answers
386 views

How does solar activity affect the ISS?

Currently the sun is launching some intense solar flares. http://www.guardian.co.uk/science/2011/feb/17/solar-flares-northern-lights-uk Th article I've linked also mentions how a "coronal mass ...
6
votes
2answers
398 views

Using energy from sun magnetic field

Knowing ...
3
votes
2answers
390 views

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 ...
4
votes
3answers
558 views

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 ...
12
votes
2answers
361 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 ...
4
votes
1answer
1k 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?)