Questions regarding the closest star to Earth, at the centre of the Solar System.

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1answer
376 views

Solar Noon: meridian crossing time versus time of maximum elevation

According to the first paragraph of the Noon Wikipedia page, solar noon is the moment when the Sun crosses the meridian and is at its highest elevation in the sky. The wording there suggests that ...
4
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1answer
98 views

Cooling of stars

If all stars suddenly stopped producing heat (or heating up) which stars would cool to absolute zero first and how long would it take?
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2answers
131 views

How many minutes does a sundial change every day?

I'm planning to create a sundial in Ghana (10° 28.852', 0° 26.032') in July 2014. I will stay there for about 3 weeks. Do I need to adjust the numbers anywhere in these 3 weeks? I know the shadow's ...
4
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1answer
116 views

How likely is it that the Sun will destroy our electric society?

Given the studies of the Sun and similar stars and the most impressive understanding of its physics, is there any kind of probability distribution for its dangerous behavior? There are also some ...
4
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2answers
72 views

Typical wavelength of solar flare

I read that solar flares are customarily viewed in H-alpha light, as a temporary brightening of a small portion of chromosphere. What all can be interpreted from this? Is it because, energy of the ...
4
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1answer
330 views

Latest sunrise/earliest sunset out of phase with solstice?

Everybody knows that the shortest and longest days of the year occur on the solstices. However, examination of sunrise/sunset tables shows that the maxima and minima of sunrise/sunset times are ...
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4answers
189 views

Does Sun have a reflection on Earth?

The new Google Maps1 presents an actual view of Earth, with the current position of Sun illuminating half part of Earth in real time. It is quite an exquisite view. My question is based on the ...
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2answers
136 views

Is the Sun homogeneous?

Does the Sun have the same composition and density everywhee within it? How does it vary in other stars?
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3answers
160 views

Does the Sun have hard radiation?

Does the Sun spread hard radiation waves around the Solar System? If so, why are we safe here (or are we even safe)?
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1answer
207 views

Do telescopes harm while observing sun through them?

I don't know whether we can observe a sun through a telescope. But if we can then will it harm our eyes and if such telescopes exists what is their configuration?
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1answer
30 views

How can the Advanced Composition Explorer (ACE) warn of incoming solar storms?

How can the Advanced Composition Explorer (ACE) warn of incoming solar storms when is is invested with radiation? Discovery.com article Solar Storm Warning Satellite on Last Legs states that: ...
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2answers
165 views

How much mass will the Sun have when it becomes a white dwarf?

In 4 billion years, when our Sun sheds all of its outer gas layers and turns into a white dwarf, how much mass will the white dwarf have compared to what the sun has today? Will the planets still ...
3
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2answers
44 views

How does solar activity (e.g. flares, coronal mass ejections) change over the life cycle of a Sun-like star?

As a Sun-like star is born from a collapsed nebula and generates energy by nuclear fusion some of that energy is converted to magnetic fields which fuel solar activity. How does that activity evolve ...
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1answer
88 views

Motion of the sun as observed from mercury

I recently found this animation which shows the motion of sun as observed from mercury. It seems as if the sun stops in between, retraces a bit and then continues towards the west. What is the reason ...
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2answers
127 views

Apogalacticon and Perigalacticon

What is the length of the apogalacticon and perigalacticon of the Sun and Milky Way? The general terms seem to be apoapsis and periapsis. My greatest efforts at Googling have failed miserably. If ...
3
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1answer
610 views

How to get the longitude/latitude from solar zenith/azimuth?

How do I get the longitude/latitude from zenith/azimuth? Or how can I position my sun in a 3d application? code extracted from here ...
3
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2answers
116 views

Can looking at the sun through solar viewing eclipse shades everyday harm your eyes?

I have a pair of Solar Viewing Eclipse Shades that say "Safe for Direct Solar Viewing" and would like to know if my eyes would be harmed if I looked at the sun everyday for about a minute wearing ...
3
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1answer
102 views

What is the degree of ionization is the solar photosphere?

I am wondering how many free electrons per baryon and how many free electrons per atom there are in the solar photosphere. This number depends on the abundances of the various atoms found in the ...
2
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1answer
111 views

Could a close passing star be captured by the Sun's gravity?

Earlier I read an article here stating that a binary pair of stars passed within 0.8 light years from the sun. That made we wonder why the stars weren't captured by the Sun's gravity since the sun's ...
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2answers
509 views

Is it possible to move a planet out of its orbit? At least a lighter planet?

As observed by many researches our sun will be exhausted in a distant future. So anyone thinks driving our planet (or any planet) closer to the sun for more light and heat is a solution for the life ...
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1answer
150 views

Look up current positions and velocities of solar system objects

I am working on an orbital dynamics code and, for fun, I would like to model the Sun-Earth-Moon system with my code. I can look up the masses of each object just fine, as well as average distances ...
2
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1answer
110 views

Solar System formation, considering its and universe's age

It's been said that the Sun is 4.6 billion years old, and the complete Solar System is of a similar age. The class of stars to which the Sun belongs seems to be quite common. Stars of its class can ...
2
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1answer
57 views

Did the Babylonians believe in the Heliocentric version?

It's mentioned that the Babylonians decreed that there were exactly 360 days in a year. This statement was based upon the utilization of 360 as a standard (based on the sexagesimal system) i.e., they ...
2
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2answers
184 views

Is it possible that the Sun has a binary partner (the Nemesis Theory) that has eluded detection?

I just recently learned about the theory that our Sun has a small companion star with a 26 million year orbit. This theory came about when it was realized that mass extinction events happened ...
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1answer
83 views

How do you find the altitude of the Sun if you are on the Moon?

The question is: If you stand on the equator of the Moon, at midday your position occurs when the Moon is located at the line of the node. What is the altitude of the sun at that moment? ...
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3answers
116 views

the metal distribution in our solar system

The sun dominates in our solar system. I wonder whether in every aspect the sun play the most role in our system. For example, all kinds of metals are mainly located in the sun instead of the rest ...
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1answer
117 views

Are ascending node of sun, the point of intersection of prime meridian and equator and center of earth all collinear?

I did a bit of googling but couldn't find the exact answer, so are the following 3 points collinear or not ? 1_center of earth 2_ascending(or descending) node of sun 3_point of intersection of ...
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1answer
183 views

Hour angle sunrise calculation problem

I am trying to program a sunrise/sunset calculator using this formula tutorial. If you follow the steps, eventually you get to this formula for "H" (the "hour angle"): $H = \arccos( [\sin(-0.83) - ...
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1answer
87 views

How does this strategy for chasing the sunset work?

In Randall Munroe's What If? blog he tackles this question: What is the longest possible sunset you can experience while driving, assuming we are obeying the speed limit and driving on paved ...
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1answer
1k views

In 2016, the summer solstice will coincide with a full moon. How often does this happen?

I found that the solstices work on a 400 year cycle based on this. I can't find anything similar for the lunar cycle. Is there a formula I can use to calculate the date of the full moon?
2
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1answer
53 views

Broadband spectrum of Sun

Broadband spectrum is one which is inclusive of all the observed wavelength ranges. In the case of the BB spectra of our Sun, there is a sharp (non-differentiable) kink in the curve in the UV-range ...
2
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1answer
107 views

Effect of the absence of atmospheric refraction to sun rise and sunset times

What is the effect of absence of atmospheric refraction on sin rise and sunset time? Is it will be delayed or earlier for sunrise and sunset, and why? Thank you:)
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3answers
113 views

Do we still use the term “astronomical unit” nowadays?

An astronomical unit is defined as the measurement of distance between Earth and our Sun, my question is since distances between celestial objects beyond our solar system are vast and unimaginable ...
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3answers
97 views

Mass of sun's core

It is estimated that the sun's core is about 1/5 of the radius of the sun (from Wikipedia). I know that the density of the plasma increases substantially the near the center, and that the volume of ...
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4answers
131 views

Relocation to Mars

One billion years into the future and the Sun has swollen in size and it is now not possible to live on Earth due to the heat. Mankind has relocated to Mars where the temperature is more favorable now ...
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1answer
79 views

Star class according to initial mass

Studying the stars classes for my homework (school) i learned that stars are classified by the spectral types (Harvard) and luminosity class (MKK) .. So the sun is a star class ...
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1answer
50 views

Why there are three equations governing blackbody emission?

I learnt that the spectrum of a black body can be explained using Planck distribution Rayleigh -Jeans equation and Weins displacement law Can anyone tell me why there are three different equations ...
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1answer
35 views

Does the sun have a feature like the red spot on Jupiter?

Does the sun have a feature or prominence like the red spot on Jupiter? Is there a feature that will remain as long as the red spot? Maybe beneath the surface?
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1answer
69 views

What came first: the Sun shining or the existence of helium?

This seems to be a chicken and egg problem, the sun begins shining due to hydrogen becoming helium, but it's odd that there was no helium initially without the stars. Is my logic flawed? (Note: ...
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1answer
116 views

Name and language of symbol in astronomy book

I've been working on a programming project involving Peter Duffett-Smith's Practical Astronomy With Your Calculator (3rd Ed.), which has a large number of mathematical/astronomical formulas in it. ...
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1answer
68 views

Why do we not find larger quantities of helium in the Sun's atmosphere?

The Sun currently shines because H is being burned to He, and it has been doing this for about 4.57 Ga. But when we analyze the Sun's atmosphere, we do not find unusually large amounts of He. Why not? ...
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2answers
127 views

How are East and West defined on other bodies of our solar system?

I noticed that East and West appear swapped on maps of the Sun, even though the Sun rotates around its polar axis in the same sense as Earth. See for example below Sun disk with a Venus transit ...
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3answers
344 views

The formation of absorption lines in solar spectrum

It is said that absorption lines originate from regions higher in the photosphere where the gas is cooler. The gas should be absorbing photons, then re-emitting them... absorb, re-emit, absorb, ...
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1answer
102 views

Solar maximum and minimum

What are solar maximum and solar minimum? Is there a relation between sun spots and solar maximum and minimum? Thank you!
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2answers
73 views

What triggers solar flares?

The sun is a big ball of hot plasma which contains free electrons. However, how does the absence of metallic elements in the sun generate the magnetic field to orchestrate these free electrons to ...
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2answers
144 views

What is the orbit of Earth around the Sun?

According to wikipedia and other sources, a planet and a star always move in a circular orbit around the common center of mass of the both bodies, in case of Earth and sun, this center of mass lies ...
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1answer
151 views

What are the color progression of a typical sunrise?

"Dawn simulators" are used to simulate a natural sunrise, or at least the physiological effects of one. What temporal sequence of color values (e.g., hue, saturation, brightness, and timing) ...
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1answer
38 views

How are stellar elemental abundances quoted?

Close to the bottom of page 4 of this article (marked as page 164 in the upper left corner) states Values are given in the logarithmic scale usually adopted by astronomers, A$_{e\ell}$ = log ...
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1answer
297 views

Does the sky get darker faster during the winter?

When one lives away from the equator, say at around 37° latitude, does the sky get darker faster after the sun sets in the winter as compared to the summer? Why is this the case? I believe that if ...
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1answer
220 views

Why do stars become red giants?

Disclaimer: I’m not a career astronomer. I don’t own a telescope. I have no professional credentials. But I do find this stuff fascinating, and I consume all astronomy documentaries I can. So, ...