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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303 views

The “official” mass of the sun as unit?

I'm searching for the "official" mass of the sun as a unit in astrophysics. The mass of the sun can be calculated by: $M_{\odot}=\frac{4\pi^2\times(1 \ \text{ua})^3}{G\times(1\ \text{year})^2}$ So ...
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1answer
460 views

Quantum Mechanics and nuclear fusion

I've been told that, according to QM, when Hydrogen atoms are left together there is a non-zero probability that they spontaneously fuse (I accept this bit). I've been told further that, because of ...
4
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1answer
58 views

Is it proven that all “solar” neutrinos are coming from the Sun direction?

In "Observation of 8B solar neutrinos in the Kamiokande-II detector" (Phys.Rev.Lett., 63, 16(1989), http://prl.aps.org/pdf/PRL/v63/i1/p16_1) the Figure 2 shows that only small percentage of registered ...
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6answers
3k 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 ...
6
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2answers
310 views

Is dark matter really present around the sun?

Recently I read an article that there is dark matter around the sun but if it is so, than why can we see it clearly. If it is called matter than it shall show some hindrance in radiation we receive ...
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1answer
247 views

Does a coronal mass ejection change solar neutrino emission rates?

Does the CME and neutrinos have any relation? CME is measured by Corona graphs.. How do they measure neutrinos coming from the sun? Does any of these have effects on earth's magnetic field or ...
2
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1answer
269 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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3answers
68 views

fit funtion to the Sun electron fluxes data

I'd like to fit a function to the Sun's electrons flux data (blue dots), please note that x,y axis are in the log scale. The green dots are the "best" fit from the gnuplot program. I have taken the ...
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1answer
138 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 ...
9
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2answers
291 views

Effect of gravitation on light

Einstein predicted that the gravitational force can act on light. This was verified in one solar eclipse that light from a star near to the sun's disc bent due to Sun's gravity as predicted. Since ...
3
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1answer
149 views

Why isn't sunset time in sync with solstice?

The winter solstice in the Northern Hemisphere in 2011 is on December 22. But if I look at the sunset times for a location such as Washington, DC on the USNO site, the sunset time starts reversing ...
14
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1answer
206 views

The transit of Venus and solar neutrino rates

The following question was posed at the end of Maury Goodman's June 2012 long-baseline neutrino newsletter. During the Venus transit of the sun, were more solar neutrinos absorbed in Venus, or ...
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4answers
454 views

Is solar wind positively charged?

Many times I heared that the solar wind consists of protons and alpha particles. The both are positively charged, but are there electrons in solar wind?
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1answer
159 views

Does regular sky clouds stops the sun's ultraviolet rays?

I have an argue with an ex-Doctor of Medicine about the amount of ultraviolet light reaching us under the clear day sun and under the 100% cloudy sky. To what extent we can say that the sky clouds ...
3
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0answers
94 views

Proton flux model or data at energy range up to 100 keV

I am looking for a model or at best the database of proton fluxes (solar p+) at a energy range of some eV up to 100 keV. I have already found the SOHO database: http://umtof.umd.edu/pm/ But the ...
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3answers
360 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 ...
4
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1answer
768 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?)
3
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3answers
5k views

Solar Eclipse Viewing

I know it is not safe when viewing a solar eclipse to look directly at the sun. I know you can purchase solar eclipse glasses online but how do you make your own solar eclipse glasses that are safe to ...
0
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1answer
166 views

Exist some relationship between irradiance units and wavelenght of the incident sunlight?

Exist some relationship between irradiance units and wavelength of the incident sunlight? What about irradiance? I want to establish a relationship between wavelength and irradiance, because I would ...
3
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1answer
183 views

daylight length variation from year to year

I am doing some calculations to see how many hours of light does a specific location (identified by latitude and longitude) has in a specific day of the year. Contrary to my expectations I get a ...
7
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4answers
360 views

Is there a way to create an artificial solar eclipse?

I heard this story, where they celebrated the birthday of the now defunct North Korean dictator Kim Il-sung in the 1970s and as a birthday present they created through some very complex artillery ...
1
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2answers
584 views

Could a solar flare cause the Earth's magnetic poles to reverse?

With all the hype of the impending "2012 Mayan doomsday" I was thinking it might be interesting to see what principles of physics prevent the theories of doomsday from occurring. One overarching ...
4
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2answers
518 views

What's the reason for the seasons?

In the diagram, it shows that the fundamental reason for different seasons is when the northern hemisphere is titled towards the sun there's summer in northern hemisphere and winter in southern ...
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1answer
1k views

What is actually meant by 'sun set' and 'sun rise' times, when taking into account the mirage due to light bending in the atmosphere

I’ve heard from the likes of Brian Cox that what we see of the sun during a sunset and sun rise is actually the mirage of the sun. The Sun has actually set/risen and we see it due to the way light is ...
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1answer
97 views

Neutrino beam energy

Neutrino is one of the most mysterious particles in todays physics. Even when values of some parameters like for example mass associated with it are not known (or there is great range of possible ...
3
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2answers
55 views

Can I determine whether it is night at a location by calculating only the sun's elevation?

There are many formulas for determining sunrise and sunset times for locations, but for my application I only need to know if it is day or night (given a time, latitude and longitude). After studying ...
3
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0answers
87 views

Was Aristarchos' method to compute Earth-Sun distance ever rediscovered in medieval or modern times?

Ancient Greek astronomer Aristarchos who lived around 300 BC found a method to compute the Eart-Sun distance by applying geometry. In this video about the cosmic distance ladder, at 26:30, Terence ...
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1answer
71 views

Can CMEs disturb a planet orbit?

Yesterday (March 6), a massive X-class solar flare erupted from the Sun. I was wondering if this kind of solar flares can affect in some way the orbit of a planet if aimed directly. Let's say, for ...
4
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1answer
59 views

What is the weekly average of coronal mass ejections the sun sends out?

What is the average number of coronal mass ejections that the sun sends out each week, including those that are not directed towards Earth?
4
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3answers
1k views

Does the sun cross over a given meridian line every day at the same time?

Let's say I have an imaginary meridian line over new york going from north to south. I know that the sun will not always be exactly on top of my head here in New York, but every day it will have to ...
12
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2answers
350 views

Hydrogen as a fuel in Sun

The source of Sun's incessant energy is hydrogen; which is continuously converting to helium through nuclear fusion reaction releasing energy. Why does not all hydrogen convert into helium in one big ...
0
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3answers
319 views

Sunspots formula

I used the package 'EUREQA', version Formulize, to analyse the monthly smoothed sunspot timeseries from 1750 till 2010. It gives me a simple formula, with 8 coefficients, that match data with a ...
5
votes
2answers
133 views

Is there any way to anticipate exceptional Aurora Borealis viewing conditions?

I've always wanted to see the Aurora Borealis, but never had the opportunity, since it is so rarely visible in my area (Pennsylvania). However, last week was apparently a rare opportunity of ...
2
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1answer
401 views

Steady State Temperature of an Object Orbiting the Earth

This may be irrelevant or stupid to ask but I couldn't come up with a good answer. At least, we could not agree on with my friend the other day. I would like an estimate of the temperature of a human ...
4
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2answers
80 views

Lumped circuit model of Earth and Sun as a thermal system

I want to design a thermal model of the Sun heating up the Earth. The circuit below is my own design (I don't know if there is a better way to model it. If there is, please tell me.). I want to ...
6
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2answers
467 views

Why is the sun so dense?

Looking at the radius and mass of stars on Wikipedia, I see that the Sun is the densest of all, often many times denser than other stars. Is that because only non-dense starts are easily seen from a ...
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3answers
3k views

Why is moonlight less colourful than yellow light?

Just what the title states; and this isn't an original question ... On full-moon, moonlight is almost as bright as mid-dawn ; yet there is hardly any colour visible. This is not the case with ...
5
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1answer
629 views

How to calculate how many degrees the Sun is from the horizon?

Given a position on earth (latitude/longitude, and maybe also height relative to sea-level) and a time, what's the algorithm to find how many degrees the Sun is from the horizon? And the same for ...
3
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1answer
253 views

Suns emission spectrum

I learnt that in astrophysical spectroscopy, the emission spectrum of distant stars is used to determine what they're made of. So why is it that our own Sun is emitting the whole spectrum ? (or is ...
6
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3answers
198 views

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 ...
4
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1answer
491 views

Equation for calculating the Sun's position

SunPosition Calculator calculates the Sun's postion based on the location and time. What is the equation used for such a calculation?
2
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1answer
163 views

Will the sun cool and produce a disrupting EMP?

Scientists say rare drop in sunspot activity could cause global cooling http://www.globalpost.com/dispatch/news/business-tech/science/110615/science-news-solar-flares-sunspots-global-warming ...
7
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2answers
178 views

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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2answers
392 views

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 ...
3
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1answer
272 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). ...
2
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1answer
114 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
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3answers
527 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 ...
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2answers
314 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 ...