# Questions tagged [the-sun]

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

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### Attempting to plot solar terminator using Python and Skyfield library

Problem I would like to plot the small circle defining the visible portion of Earth for an observer at position $P$ away from the Earth, on a 2D map. In the case of the Sun, this would be the solar ...
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### Where will all atoms on the Earth end up when the Sun engulfs the earth?

I am curious about what will happen to all atoms on the Earth including all of our atoms after the Sun engulfs the Earth? Will they become the part of the Sun's white dwarf? Or most of them will be ...
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### How would radiation pressure inside of the Sun affect an indestructible person?

I went down something of a rabbit hole regarding whether an indestructible person trying to walk on the Sun would fall in, and sink. I want to know how radiation pressure would affect that person. As ...
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### What does the solar analemma on earth look like at the equator? Some web sources seem to indicate it is a horizontal line. How can that be?

I'm finding several sources on the internet which say that the solar analemma at the equator is a horizontal line, but this makes no sense to me, especially the analemma at noon, for which the sun ...
1 vote
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### How is the amount and direction of the Sun's axial tilt as observed from other planets calculated?

Not long ago I asked this question; turns out that was fairly simple to figure out given the equatorial coordinates of the Sun's north pole (just convert to ecliptic coordinates, and see when the Sun ...
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### What is the solar diameter?

What is the solar diameter in SI units? Google tells me this is 1.3927 Gm. How accurate is that figure? I am looking for estimates with referenced data and calculations, and the uncertainties: due to ...
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### What were the specifics of the photos taken by Sir Arthur Eddington during the Eddington expedition that supported Einstein's Theory

I know that Sir Arthur Eddington went to South American to photograph stars around an eclipse to see if they seemed to change position when the light past by the Sun relative to when the light didn't ...
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### What is the meaning or information given by the solar image at 4500Å?

On the latest solar images from NASA, there is one picture lablled "continuum 4500 Å". There are bands diagonally in the picture as well. What is the ...
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1 vote
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### Determining Time Based on Arc Seconds

So our arc day starts at 20°41'32 which is midnight (0:00) and ends 24 hours later at 21°42'42. According to my calculations it traveled 0 degrees, 59 minutes, and 30 seconds or 3570 arc seconds in 24 ...
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### Could UV-A imaging sensor reasonably see a total eclipse in progress through clouds?

Let's suppose the ultimate disaster occurs... you've blown several thousand dollars on travel & lodging to view an eclipse, and now... minutes before the big event... the sun is behind a cloud. ...
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### On what four dates dates do we observe the minimal, maximal, and two days of zero Solar axial tilt relative to us?

In case the title is a bit confusing, what I'd like to know is essentially respectively on which dates the Solar axial tilt is pointing straight towards Earth, straight away from Earth, and ...
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1 vote
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### Tracking the position of the sun at various times of the day and night for a particular location

I am looking for a website that will provide me with the degree above and below the horizon of the position of the sun at various times of the day and night for a particular location. looking for ...
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### Resolving variance between Skyfield-generated sun vectors and test data when both use same ephemeris

I have two functions that get TEME and GCRS Earth-Sun position vectors using Skyfield: earth_sun_vectors.py ...
1 vote
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### calculating apogee and perigee for moon and sun

The perigee does not necessarily happen when we have a full moon, using swevents we can easily determine the moon phases. Now can we use python to determine when ...
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1 vote
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### Looking for data and models for events of Sun and Moon apparent motion in distant past?

For the current Julian Era (from 1, 1, 4713 BCE to modern day), I am looking for a raw data tables or a model that allows to predict the following events related to apparent motion of Sun and Moon: ...
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### Fixing satellite eclipse equations from textbooks that are seemingly failing

I have tried implementing equations from two different textbooks in Python to find if a satellite is in eclipse, but both fail a significant percentage of the time when tested against data from ...
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### Is it possible to view the sun and moon in the sky at the same time?

I'm writing a story. I want my ending to have the sun and moon visible in the sky at the same time. It is symbolism for the larger story. Is this possible? I have tried searching and can't find ...
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### The star that created our sun

Is the location of the star that would have created our sun known? Meaning our sun's parent star which would have provided the material when it died? If not, has there been any theories on what kind ...
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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 ...
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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. ...
• 505
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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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### 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 ...
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### 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 ...
• 1,467
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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. ...
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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 ...
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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 ...
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### 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 ...
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### 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 ...
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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 ...
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### 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 ...
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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, ...
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### 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 ...
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### 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 ...
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### 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
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### 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 ...
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### 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
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### 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 ...
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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 ...
• 23
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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 ...
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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
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### 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 ...
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