Questions tagged [the-sun]

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

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1answer
2k views

How deep is the “A” Fraunhofer line in the solar spectrum? Is it from the Sun's or Earth's atmosphere?

Question: Where can I see - or even download - a fairly high resolution (~0.1 nm) solar spectrum at zero air mass - in other words from space without absorption and other features from the Earth's ...
3
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1answer
817 views

Expression for length of sunrise/sunset as function of latitude and day-of-year

I would like to know how the length of sunrise/sunset (and also time between civil/nautical/astronomical twilight) varies with latitude and with day of year. Ideally what I am looking for is an ...
3
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2answers
2k views

Photosphere is relatively transparent. Is that right?

This book, Astronomy in Minutes: 200 Key Concepts Explained in an Instant, by Giles Sparrow, says the photosphere is a visible surface at first, but after that, it says the Sun becomes cool and then ...
2
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1answer
94 views

Are there any ways in which the light time difference between the center and the edge of the solar disk is noticeable?

In the ABC News video New space discovery has astronomers buzzing at about 02:30 Dr. Hakeem M. Oluseyi explains that the shortness of FRBs (before dispersion) suggests a compact source size and ...
2
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1answer
106 views

Solar azimuth for celtic fire festivals

I am pretty new to astronomy, and I have fallen down rabbit hole creating a new Metonic calendar in Javascript. As part of this I would like to calculate when the sun is half way between a solstice ...
2
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3answers
308 views

How moon is visible during sun is still shining, simple explanation please! [duplicate]

Sometimes I observed there is moon on sky at noon and sun is also shining. How is this possible? I also observed dull moon is still on sky at 7:00 AM to 8:00 AM while sun is rising. My local time is ...
2
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1answer
73 views

Helioseismology of the Sun, what is actually measured?

Wikipedia's article Helioseismology outlines several ways to analyze, data but is fairly thin on the nature of the measurements themselves. Are there hundreds or thousands of high resolution ...
2
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2answers
477 views

As the Sun dies, does the Earth's orbit change?

As the Sun nears the end of its life and expands, would the Earths orbit get bigger as it moves out or would it stay in the same orbital plane and not move out? Therefore in the far off future, we'd ...
2
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2answers
299 views

Will a Ball placed close to Sun fall into it?

Like a ball falls on the earth due to gravity, if suppose we are able to place a ball close enough to the sun. Will the ball fall into the sun due to its gravity or will it be pushed away due to its ...
1
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0answers
46 views

What does the Sun “look like” below 100 MHz?

Radio2space.com's The Radio Sun says: At very low frequencies (below 0.1 GHz) and therefore at very long wavelengths (> 3m) the solar disk appears much bigger and brighter in the center, and its ...
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1answer
98 views

What is the exact time of sun stay in each zodiac every year on sidereal year duration?

I tried to reverse engineer from astro-chart times at which sun stays in a zodiac. Here is the list. ...
0
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1answer
463 views

Does the Sun's atmosphere have a scale height?

Much of the Earth's atmosphere has a scale height $h$ of roughly 7 to 8 kilometers such that the local density varies as $\exp(-(r-r_0)/h)$ where r is the radius vector and $r_0$ would be some ...
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1answer
139 views

Why do years become shorter with time?

I've read (in Gates to the Hebrew calendar p.128 and other sources) that the Earth orbits the Sun in 365.256 days, but each 1000 years the year becomes shorter by 5.5 seconds. "The accurate ...

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