Questions tagged [the-sun]

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

40 questions with no upvoted or accepted answers
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287 views

Linear limb darkening coefficient, u

I was wondering if anyone knew of any resources to understand the linear limb darkening coefficient, $u$. That is to say, how the $\theta$-dependent coefficient $u$ (or sometimes $b_{\nu}$) varies ...
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39 views

How does SOHO know what's going on in the sun's magnetic feild?

SOHO can image the sun's magnetosphere. I don't have the foggiest idea how they manage it, because at most a satellite can have a single compass, and measure one point in the magnetic field. I thought ...
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49 views

What is happening with these solar particles detected near the Sun that is so newsworthy?

Phys.org's Team identifies low-energy solar particles from beyond Earth near the Sun links to the open access ApJ article Properties of Suprathermal-through-energetic He Ions Associated with Stream ...
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47 views

Simulate earth, moon, sun constellation with dates

I would like to simulate the three object distance, specifically the distance of the moon to both, sun and earth for further investigation into tide prediction. What would be a good starting point ...
4
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67 views

Did Eudoxus describe the eclipitic on his sun motion model?

In the description of Eudoxus’s model for the sun he says one the three circles which describe solar motion is “the circle which runs along the middle of the zodiac”. Does this refer to the ecliptic ...
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81 views

Information on Planetary nebula formed from the death of our star the 'Sun'!

I want to know the expansion rate, composition, mass and density of hydrogen present of a Planetary nebula similar to that which will be formed after the death of our star the sun. Knowing these ...
3
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48 views

Why do CME's “zig-zag” on their way to Earth?

This answer to When a coronal mass ejection (CME) hits a spacecraft, from which direction will the particles come? states: A single CME will impact a spacecraft from only one direction, but that ...
3
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69 views

Does the Sun have a numerical designation in any star catalogues?

Given the existence of large star catalogues listing millions of astronomical objects with numerical designations (such as Tabby's Star, KIC 8462852) it occurred to me that one of them might contain ...
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198 views

What are the experimental limits to the residual charge of the Sun?

The question Can a Neutron Star become charged? and the associated comments and answers started me wondering; Are there measurements of, or experimental limits to the residual charge of the Sun? ...
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65 views

How to get SOHO Satellite images' coordinates?

I'm working with images from LASCO C3 coronagraph I'm able to download pictures from LASCO C3 using this form https://sohodata.nascom.nasa.gov/cgi-bin/data_query Then, I want to do some analysis of ...
3
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492 views

How is the time of sunrise and sunset determined?

If I do a quick Google search for amsterdam sunrise, I immediately get the time back: 6:42 AM. How is this time calculated? (I ...
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98 views

Calculating the position angle of the moon (the rolling back and forth)

I have been watching the the NASA Moon Phases Video of the year 2020. Pretty much everything makes sense and I know how to calculate it including the moon phases, declination, azimuth, apogee and ...
2
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89 views

How do I calculate moon phase orientation at any Coordinates given all the necessary data?

I'm having a problem for a couple of days where I'm trying to accurately calculate the phase angle of the moon at any given Coordinates (lon,lat).If I know my current Coordinates, Moon and sun ...
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92 views

Orbital decay of the Earth's orbit and Earth's moving closer to the Sun

If we consider orbital decay of the Earth's orbit, then can we counter argue with the following reasons? Due to tidal effects transferring small amounts of angular momentum from the Sun's spin to ...
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165 views

What is the great (platonic?) year? How could it be explained in laymen's terms?

How could a great year be explained in laymen's terms? According to the definition in NASA's Aerospace Dictionary it is a complete cycle of the equinoxes around the ecliptic that completes in 26000 ...
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74 views

Is there any formulae to calculate whether the sun will depress 18 degrees or more below the horizon on a certain day / location?

I'm trying to code a piece of software which will calculate some times for me that would greatly help me in my day to day but none of my formulae work if the sun doesn't go at least 18 degrees below ...
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36 views

Aaditya L1 mission ISRO

ISRO's next mission to the Sun is Aditya-L1, (also here), which will be placed at the Sun-Earth Lagrangian point L-1. Why it is not placed near L-4 or L-5, since these are stable equilibrium point ...
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163 views

Observed sun/moon rise/set times to nearest second?

Where can I find a list of observed (not computed) sun/moon rise/set times to the nearest second, along with the location (latitude, longitude, altitude [or enough information to find these three ...
2
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1answer
72 views

How well can the Sun's surface be resolved by an observatory?

There's no lack of photons, how well could a telescope resolve Sun spots and other surface features of the Sun? How would a high resolution Solar (space) telescope differ from for example Hubble which ...
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32 views

Does anyone know about the ring diagram technique and Helioseismic and Magnetic Imager pipeline?

I'm working on the ring diagram technique and pipeline for the Solar Dynamics Observatory's Helioseismic and Magnetic Imager or HMI, but I didn't find much about the details about how it works or how ...
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78 views

Why are helium resonance lines called “resonance lines”?

Examples of the use of the term: Formation of the helium extreme-UV resonance lines On the Formation of the Resonance Lines of Helium in the Sun (unpaywalled) Formation of the helium EUV resonance ...
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66 views

What is the dielectric constant of a star?

1) What is the dielectric constant of a star, especially its corona? Is it of order 1 or is it quite large? 2) How much do "impurities" (elements other than H and He) affect the dielectric constant?
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32 views

Angle of the Sun during winter solstice

What is the angle of the Sun on the eastern horizon at 35° latitude if it is the winter solstice?
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45 views

Angle between earth's angular momentum and earth's axis

I think this picture is correct because for earth astronomical day is slightly shorter than solar day. (Is it a rule of thumb for planets? Where can I read such data?) Source So the angle between ...
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41 views

Looking for a 3D animation showing the motion of the sun relative to other stars and the Milky Way, any one seen anything like that?

I am looking for an animation that not only shows the inclination of the solar system respective to the plane of the galaxy, but also shows the motion of the sun relative to and in conjunction with (i....
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48 views

Tracking a heliographic coordinate on CCD

Given the latitude and longitude of a heliographic coordinate, I want to place the point on a CCD image and simulate its motion for a particular duration. Though I am able to track the motion of a ...
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38 views

Tracing back OMNI data to the sun

I have been reading the OMNIWeb data documentation in order to clarify one particular question without success. I need to associate each measurement in the OMNI dataset to a moment in time at the sun (...
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182 views

How do I calculate the barycentric position of the sun at a given julian date?

I have used the (matlab/octave) SOFA routine/function iauEpv00 to get the barycentric position and velocity of the Earth, but now need to find barycentric position of the sun. Can't seem to find the ...
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58 views

Visible Light Ground-Based Solar Observatory Data Archives?

I'm mainly searching for the best(or good/significant/important) solar data archives via ground-based telescopes. If I'm not being very straightforward... Say if I wanted high quality/resolution ...
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1answer
103 views

How low can the sun be seen in the sky?

I'm interested in knowing how low the sun could ever get in the sky and still be seen. More technically: what's the minimum possible elevation of the sun at which it can still be seen above the ...
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48 views

A question about Sun disk deformation

Suppose the Sun rises and due to refraction the Sun's disc gets deformed. Let the center of the sun be $O$ and $OL$, $OR$, $OT$, $OB$ be the distances from the center of the disc to the edges in the ...
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22 views

Why were solar constant measurements before TSIS-1 all about 0.3% high?

Phys.org's Solar energy tracker powers down after 17 years says: "The big surprise with TSI was that the amount of irradiance it measured was 4.6 watts per square meter less than what was ...
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77 views

Could the Sun's planetary nebula be dangerous for the planets?

Since the Sun's mass isn't high enough it won't go supernova being a red giant but instead release a planetary nebula. So that seems to be kind of a substitute for a supernova. Would ejecting the ...
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18 views

X-rays, Solar wind and Sun's corona

I was reading that Solar corona emits the solar wind however also X-rays. What is the difference during the creation of these effects and impacts on our atmosphere? Thank you!
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57 views

Calculating angle between the sun and a perpendicular to earth given lon/lat & time

If you had your longitude/latitude, and the time/date, how could I go about working out the angle between your normal and the sun? At first I was doing a simplistic approach of assuming elliptical ...
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44 views

Astronomical events and Celebrations

In the past people celebrated important astronomical events and some of those events are still celebrated in some cultures and traditions. For example: March/September equinox, New Moon, Winter/...
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32 views

Stellar interior structures

im really confused on how i relate mass to radius of a star with a non constant density. more specifically i cannot seem to find an equation that states how density varies throughout a main sequence ...
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27 views

what/how do we mean/derive statistical equilibrium equation of certain energy levels?

While reading the research paper "Excitation of the Fe XIII Spectrum in the Solar Corona" by D.R. Flower and G. Pineau des Forets in the summary I found the concept of statistical equilibrium equation ...
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1answer
98 views

Where can I still find solar film?

I, like many others, am excited to see the eclipse. I want to view the eclipse through my telescope, however, I don't have any solar safety equipment for solar viewing and I cannot find any online ...
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1answer
472 views

What percentage of the sky could the sun be in?

For every location on earth, there are parts of the sky that the sun can never be in (e.g., directly overhead anywhere outside the tropics). I think the sun can be in about 40% of the sky (a ...