# Questions tagged [the-sun]

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

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### Flux from the Sun on the Earth using the Stefan-Boltzmann law

What is wrong with this computation, plase? I am getting the result of 4291.65 W m^{-2} instead of 1361 W m^{-2}. Thank you very much ...
• 485
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### Integration of Plank curve of the Sun

Why I did not get the value of 1361 W m^{-2}, please? I am getting 2.0125538614437745e-47. ...
• 485
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### Why did the dust between the planets disappear during the birth of the solar system?

I'm catching up on my childhood mistakes. One of them was the "nuclear flash", the enormous explosion when the sun ignited. Apparently, this did not happen as the ignition of the sun was a ...
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1 vote
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### Equation for calculating boolean answer to "is this Earth satellite in eclipse"

I have found plenty of math for determining duration of satellite eclipse, but I am having trouble finding an equation that produces a simple boolean answer to the question "Is this Earth ...
361 views

### How did the temperature of the solar system evolve?

As a child, I've read that stars ignite during a so-called "nuclear flash". I understood this as a very violent outburst of energy from the sun, causing all dust between the protoplanets to ...
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1 vote
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### is there anything that might cause a planet to stop getting sunlight permanently, or to only have light infrequently? (on the whole planet or part)?

(writing a story) Is there anything that might cause all or part of a planet to stop getting sunlight, or to have a permanent/ridiculously long-lasting perpetual twilight? nuclear winter? volcanic ...
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1 vote
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### How close can Venus be to the sun in the sky and still be visible to the naked eye?

Assuming no artificial light, what is the minimum number of degrees apart would the sun and Venus have to be during the beginning of civilian twilight for the planet to be visible to the naked eye to ...
• 1,447
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### How is an index of n=0 possible for the Lane-Emden equation?

I was recently showing that an index of $n=0$ for the Lane-Emden equation results in constant density throughout the star. However, in my calculations I had to use the constant $\alpha$ which can be ...
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1 vote
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### Why does the sun appear on the screen behind an eyepiece when doing solar projection?

I've seen Youtube videos explaining how to "safely" observe the sun by projecting an image of the sun onto a piece of cardboard behind the eyepiece of a refracting telescope or binoculars. ...
• 275
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### How did ancient models explain 6 months of day and night at the respective poles?

We know that the Arctic circle experiences 6 months of continuous day light during the sun’s apparent northward journey (to the solstice) and vice verse for the Antarctic region. This is attributed to ...
• 201
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### Anomaly in official video of the today's solar eclipse

I watched an official nasa video of the solar eclipse that happened today. https://t.me/uniannet/114510 - link to the news channel where the video was posted, not original. At the fifteenth second of ...
103 views

### Estimate the mass of Saturn based on the given data below

In September 2017, the Cassini 1 mission was nearing its end after 20 years due to fuel shortages. The NASA space probe reached its apoapsis on 12 September at 1:27 AM EDT (time on Saturn) with a ...
4k views

### How much of the surface of other planets is lit by the sun?

Since the sun is much larger than the earth, it should ideally light up a considerable portion of the earth rather than only half of it. However the sun lighting only half of the earth can be ...
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### Error in "Efficient Method for Calculating the time of Sunrise and Sunset" by Robin G Stuart

I've been implementing this paper in python. "Efficient Method for Calculating the time of Sunrise and Sunset" by Robin G Stuart. The sun's equation of centre is incorrect no matter what I ...
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### How to describe the Sun's location to an alien from our Galaxy?

Let's say you got to the planet orbiting other star in our Galaxy through the wormhole. You think that the travel was instant but you're not 100% sure and it is not exactly known. The planet is ...
• 133
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### calculating the position of the sun by using degrees and determining date and time

so i found this code and even looked up the documentation on swe_suncross() most i've seen its - 88 degrees but can one determine this using any degrees ...
423 views

### Is Venus in our sun's habitable zone?

I know that Venus is closer to the sun than Earth and if an article I read is to be believed, Venus is hotter than Mercury even though the latter is closer to the Sun. The explanation for this odd ...
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### Does most of the Sun's energy and light come from its black-body temperature, due to its massive size alone? Constant crashing of particles?

Stars have to be a certain size to initiate fusion to begin with, correct? Isn't this why brown dwarfs are considered 'failed stars'? But wouldn't the Sun (and other stars with sufficient mass, like ...
• 4,891
1 vote
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### Does the Sun have different unique orbits around barycenters?

After reading this question and seeing its image I thought about this question I'm going to publish. Does the Sun have different unique orbits around the barycenter for its multiple planets? If yes, ...
1k views

### How do people of the opposite side see the Moon and the Sun?

I was looking in the StarTracker android application from Tehran, Iran; and this is the screenshot: As you can see the Moon covers a small portion of the Sun. The green line above them is the ...
135 views

### Calculating Position of Sun in GPS Frame Relative to 0°00'00.0"N 0°00'00.0"E: Determining Vernal Equinox Offset

I am trying to calculate the position of the sun, in GPS coordinates terms, from a given date. As of right now, I know how to accurately calculate the equatorial Right Ascension and Declination, and ...
3k views

### Did the Sun's light always peak in the green wavelengths?

So, I know the sun is getting brighter over it's lifespan and I'm wondering how that affects its emission spectrum. The reason I'm asking this is because I find it weird that plants reflect green ...
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1 vote
143 views

### Sun or moon, finding the date and time of crossing a specific longitude

the Sun is currently in Virgo ♍, 13°7'9" or longitude 56.0762 degrees how does one calculate when exactly the Sun will reach this position again. Since the moon is doing a spin in 29.x days lets ...
883 views

### Is there a (proposed) name for Coatlicue's progenitor?

Our sun's theorized progenitor star carries the (proposed) name Coatlicue. Since our sun is thought to be a third generation* star there should be two generations preceding it - and therefore one ...
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I have just purchased a Coronado Solarmax III 70mm. To make it clear I am not an astronomer or an astrographer. I just need the telescope for an art installation purpose. I am having trouble with ...
1 vote
301 views

### Why isn't a month 28 days?

1 days is a rotation of earth. 1 years is an orbit of the sun. I've always beleived that one month is 1 period of the moon orbiting earth but the inconsistent distribution of days throughout the ...
• 119
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### lunar north node in heliocentric terms?

I am wondering how to get the heliocentric longitude and latitude for the Lunar North Node, for example. I have been able to extract from the Swiss Ephemeris api the geocentric and heliocentric ...
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### How old are the total solar eclipses as we see them today? [closed]

I've seen it referenced often that "total solar eclipses" (of the kind we see today where the corona of the Sun is visible as opposed to all of it being blocked) have become possible only ...
• 305
1 vote
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### Celestial Navigation - How to calculate Longitude?

I'm trying to learn celestial navigation using the Sun to determine longitude. I'm starting to understand some of these concepts, but I can't figure out how to calculate longitude accurately. Hoping ...
1 vote
66 views

### Will the Earth tidally lock to the Moon (ignoring Sun's expansion)

At some point, won't the tidal forces from the Moon be less than the ones from the Sun? Would that mean that the Moon stops moving away, or would the process still continue. Would the Earth start ...
• 155
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### Planets revolving counter clockwise around the Sun

Planets revolving around the Sun Hypothetical case: What could have been or no impact if the planets viz Earth, Jupiter, Saturn, Mercury, Venus, Mars, Pluto, Uranus, Neptune in different orbits ...
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### To what extent does the increased average airmass the Sun's light passes through contribute to the seasons?

The traditional explanation for the cause of seasons I have heard is that because of the angle of the axis of the Earth with respect to the ecliptic, the angle at which light rays hit the Earth's ...
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### How did we figure out that Stars become red giants and when did we find out that they will?

I always hear that the Sun will be one but never when we found that out or how.
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### Demonstration- formula for angle between horizon and ecliptic

The most precise and quite intuitive formula I could find online is here: https://www.celestialprogramming.com/snippets/angleBetweenEclipticAndHorizon.html \cos I = \cos ϵ \sin ϕ − \sin ϵ \cos ϕ \...
111 views

### If the distance from Earth to the Sun was filled with air, how loud would the sun be?

Based on this question: If there was air between the Sun and Earth, how warm would we get? Many sources state that if sound wasn't limited by matter, we would hear the Sun at around 100dB constantly, ...
1 vote
86 views

### Where do these materials on the Sun come from, if not nothingness?

In this video, I see that for hours, it seems that the flow keeps going from the 11h direction to the Sun's surface - while there looks like nothing is coming to the top of the loop to provide a ...
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### Which star has the highest known metallicity?

Which star has the highest known metallicity? The highest I know of is Sirius Which a Metallicity of +0.5, which corresponds to have a Ratio of Fe to H 3 times that of the sun.
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### Is the Sun hotter today, in terms of absolute temperature (i.e., NOT total luminosity), than it was in the distant past?

I am constantly reading that the Sun is at least 20% 'hotter', in terms of total radiation/luminosity, than it was a few million years after its formation (i.e., after the Hayashi stage...) But what ...
• 4,891
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### Where can I download the historic sunrise and sunset times for a location?

As the question indicates, I would like to know the sunrise and sunset times of a location. This is to evaluate the impact of day and night variations of a time series. Is there a way to download this ...
258 views

### How to calculate the apparent magnitude of sun?

I know the apparent magnitude of sun is -26.74, but I wonder how to get this value if we don't know the absolute magnitude? Thanks!
1 vote
282 views

### How do the phases of Venus prove heliocentrism?

I have been doing research about the Copernican Revolution, and one of the main arguments that caused many astronomers to change their minds was Galileo's observation of all phases of Venus. The proof ...
• 131
1 vote
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### Will the Sun fall into a black hole? If so, when and which one?

According to the Wikipedia page "Timeline of the far future", stellar remnants not ejected from their galaxies will fall into the central supermassive black holes over a time scale of around ...
• 145
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### Radius and surface temp of red giant Sun [duplicate]

There is wildly conflicting information going around about the predicted parameters of the Sun as a red giant. The estimates for the radius vary from 100 to even 256 solar radii (with the larger ...
202 views

### How close is a typical New Moon to the Sun in the sky?

In a Solar Eclipse, the Sun, Earth and Moon are exactly colinear (well some area of the Earth where the eclipse is visible), and these are relatively rare. But in addition, Sun, Earth and Moon are ...
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### Visibility of solar flaring region from Jupiter

I numerically calculated the following numbers. The geocentric longitude of the Sun on 25 November 1999 at 00:00 UT was 243.52 degrees (numerically calculated with an error of 1 degree). On this date (...
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### How will the expansion of the Sun influence Earth as a celestial body after 5 billion years?

Science news have flooded our news feed again about how our Sun could swallow Earth. This time due to a real documentation of a similar event in an other system. theguardian washingtonpost From what I'...
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### Bremsstrahlung's role in the sun

Due to nuclear fusion that produces gamma rays which goes through compton scattering, in the end, on the surface, visible, infrared light ends up as before then, gamma rays lost energy and became x-...
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### the sun - relationship between gravity and temperature

In the sun's core, we know it's very hot. I was curious to research why it was exactly and I think 99% of answers are not fully correct. They say that it's because of nuclear fusions. I'd not agree as ...