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Questions tagged [the-sun]

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

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Why do the Sun and gas planets rotate faster at equator than at poles?

From this site, it states that: The Sun spins faster at its equator than at its poles. I have also read somewhere that the gas giants (gaseous planets like Jupiter, Saturn, Uranus, and Neptune) also ...
apk's user avatar
  • 949
6 votes
0 answers
480 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 ...
MichaelJRoberts's user avatar
5 votes
0 answers
37 views

Help understanding ring diagram analysis used in helioseismology

I need help understanding something. In global helioseismology we study the modes directly (stationary waves characterized by 3 integers numbers: $n$, $l$ and $m$). As the angular degree $l$ becomes ...
Daniel's user avatar
  • 51
5 votes
0 answers
97 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 ...
El Dude's user avatar
  • 151
4 votes
0 answers
92 views

Unknown satellite transit during solar eclipse on April 8, 2024

While viewing the April 8, 2024 solar eclipse from Jackson, MO, when the moon had eclipsed about 20% of the sun (the bottom-right part), my friend and I both observed with our naked eyes (behind solar ...
Tyson Williams's user avatar
4 votes
0 answers
59 views

How are plage regions related to the density of medium and velocity FeII ions?

During a literature review (abstract), I found that the intensity of FeII (298.5 nm) ions in the last solar minimum was higher than the two previous solar minima 21 & 22. The velocity of FeII ions ...
Autodidact's user avatar
4 votes
0 answers
72 views

Did astronomers "track back" solar wind switchbacks to the surface of the Sun to individual convection cells?

The new NASA Goddard video NASA's Parker Solar Probe Touches The Sun For The First Time explains that the spacecraft passed many times through "switchbacks" or kinks in the solar wind, where ...
uhoh's user avatar
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4 votes
0 answers
80 views

From what distance could the Sun's planetary nebula be seen entirely with free eye?

When collapsing to a white dwarf, a red giant Sun would emit a planetary nebula. How far from the Sun would that nebula stretch at most? Also: At about what distance could you see the planetary nebula ...
Plutos Loyer's user avatar
4 votes
0 answers
60 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 ...
Retracted's user avatar
  • 141
4 votes
0 answers
1k 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 ...
The Oathman's user avatar
4 votes
0 answers
82 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 ...
Fran's user avatar
  • 41
4 votes
0 answers
45 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 ...
Gauti's user avatar
  • 529
4 votes
1 answer
206 views

What does the surface of a star look like in visible light?

False colour images of the Sun show a highly complex structure near the surface with matter ejected and suspended in magnetic fields. But are solar prominences and coronal mass ejections visible to ...
dubious's user avatar
  • 141
3 votes
0 answers
92 views

Sun and moon same angular radius - how unlikely is this?

How many planets do we expect, statistically, in the universe, have a sun and a moon with such a similar angular diameter as we do on earth? How many habitable planets? Is it possible to calculate ...
Rabbi Kaii's user avatar
3 votes
0 answers
74 views

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 ...
Peter's user avatar
  • 31
3 votes
0 answers
116 views

What is the average and the median mass and luminosity of a star?

I've heard in many places that the Sun is an average star, but in Wikipedia it says that about 75% of stars are M-type stars that are way less massive and fainter that the Sun. So how massive and ...
HugoF's user avatar
  • 186
3 votes
0 answers
63 views

How is the incidence angle of the Sun related to the lean angle of the Cooks pines?

Auracaria columnaris (Cooks pine) on average lean towards the equator. Most of the pines in the Northern Hemisphere lean southward and most of the pines in the Southern Hemisphere lean northward. ...
Connor Garcia's user avatar
  • 16.3k
3 votes
0 answers
48 views

Classical Mechanics : Interaction Sun Radiation Pressure - Gravitation

I have a theoretical problem that merges the effects of a gravitational field and the Sun radiation pressure. The problem goes as follows: A spacecraft orbits the Sun in absence of any other body ...
SERGI LÓPEZ's user avatar
3 votes
0 answers
121 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 ...
Tushar Sharma's user avatar
3 votes
0 answers
88 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 ...
Maxim's user avatar
  • 31
2 votes
0 answers
72 views

Closest/farthest point where the sun stops being the brightest star?

Which is the closest point to the Sun where it's not the brightest star anymore? My intuition is that this is either on a direct line between the Sun and Alpha Centauri, or between the Sun and Sirius ...
Michael Borgwardt's user avatar
2 votes
0 answers
70 views

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 ...
Kian31's user avatar
  • 21
2 votes
0 answers
57 views

Ghost images coronado telescope

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 ...
Clint Calleja's user avatar
2 votes
0 answers
115 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, ...
dependsonmany's user avatar
2 votes
0 answers
41 views

Display the lines of solar altitude on the map

Following this question: Calculate lines of equal solar altitude I would like to have the possibility of displaying the lines of equal solar altitude on the map as per the image below: including also ...
Geographos's user avatar
2 votes
0 answers
92 views

Are there two mean Suns?

Are there two mean Suns? In the book I'm reading, the authors appear to refer to a mean Sun on the ecliptic moving in a circular orbit with constant angular velocity and with the same orbital period ...
Peter's user avatar
  • 1,033
2 votes
0 answers
766 views

Calculating local solar time with python ephem library

I was learning to calculate local solar time with ephem. I must admit, unit conversion between radians, hours and days, which are all represented by a float in the ...
Sati's user avatar
  • 121
2 votes
0 answers
132 views

Help finding a database or analysis of plage regions on the Sun

Plages are phenomena of stellar activity. A plage is a bright region in the chromosphere of the Sun, typically found in and around active regions. The term itself is poetically taken from the French ...
Autodidact's user avatar
2 votes
0 answers
54 views

What is the sun's maximum influence on a magnetic object?

How much magnetic repulsion could the sun's magnetic field produce on an magnetic object? Consider the object is ideal: It could be flat, to create more resistance, balanced, to stay on the opposing ...
Justintimeforfun's user avatar
2 votes
0 answers
2k 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 ...
The Oathman's user avatar
2 votes
0 answers
109 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 ...
Tapi's user avatar
  • 121
2 votes
0 answers
64 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 ...
Maddux123's user avatar
2 votes
0 answers
646 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 ...
Kevin's user avatar
  • 183
2 votes
1 answer
89 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 ...
LocalFluff's user avatar
  • 11.4k
1 vote
0 answers
51 views

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 ...
Outis Nemo's user avatar
1 vote
0 answers
115 views

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 ...
dimitri33's user avatar
  • 167
1 vote
0 answers
56 views

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 ...
sunwatcher's user avatar
1 vote
0 answers
50 views

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: ...
Suiinditor Impudens's user avatar
1 vote
0 answers
70 views

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 ...
Zeantra's user avatar
  • 11
1 vote
0 answers
56 views

How does the entropy diffusivity changes with radius in the Sun?

Could you please explain - How does the entropy diffusivity changes with radius in the Sun? As far I know, In the convection zone, the entropy diffusivity increases as the temperature and density ...
stayhappy's user avatar
1 vote
1 answer
149 views

What is a place to find raw numbers of sunspots from the past, as counted daily by sun observer?

What is a place to find raw numbers of sunspots from the past, as counted by sun observers ? I have already visited 100+ of websites (NOAA, NASA, ESA, Japanese Institute ..) and what is offered is ...
darius's user avatar
  • 61
1 vote
0 answers
82 views

Does the north pole of the Solar System (with respect to the invariable plane) point towards the galactic center?

How is our Solar System as a whole (not the wobbly Earth) tilted with respect to the invariable plane of the Milky Way? I understand our Sun's north pole is largely pointing towards our direction of ...
Kurt Hikes's user avatar
  • 5,087
1 vote
0 answers
47 views

Data of Coronal Holes

I'm working on the Evolution of coronal holes for which I need data of Coronal Holes, I have searched on internet and also done literature survey but didn't find out any open-source catalogue where I ...
Autodidact's user avatar
1 vote
0 answers
98 views

Ecliptic and it's poles

Well, I have this picture and a couple of tasks to it: It is the Sun's path, a.k.a. ecliptic in autumn, 22-23 of September or on the day when autumnal equinox happens. I am to answer these questions: ...
ALiCe P.'s user avatar
  • 1,017
1 vote
0 answers
34 views

which fraction of the solar radiation corresponds the blocked part by Venus at its transit upon he sun?

Well, asumming that Venus orbits the Sun at 0.7233 AU and its diameter is 12,104 km, I can conclude that its angular diameter seen from the earth is ~1', then its represents ~1/31 part of the angular ...
Esteban Vera's user avatar
1 vote
0 answers
151 views

Solution of stellar structure equation for Sun in Convective Zone

Consider the following problem: Sun has a convection zone from $0.7 R_\odot$ to the solar surface, when $R_\odot$ is the radius of Sun. If the matter is marginally convectively unstable and the ...
Young Kindaichi's user avatar
1 vote
0 answers
220 views

Are sunspots named or individually tracked?

This is a follow-up question to How are the solar flares from May 23, 2021 extraordinary? which is about news of spaceweather.org. In the present question, I am curious solely about sun-spots and why ...
B--rian's user avatar
  • 5,616
1 vote
0 answers
254 views

Finding Observer Latitude/Longitude - In Simple Terms

I was wondering if someone could explain to me in simple terms how to determine the observer latitude/longitude at a given location. For instance, if an observer is positioned at Cleveland, Ohio, how ...
Sue's user avatar
  • 11
1 vote
0 answers
600 views

Calculate position of sun in sky

I would like to calculate the angle formed by the sun and the horizon for any hour of the day and any day of the year for a particular place on Earth. So like: what is the angle of the sun to the ...
Mark Polczynski's user avatar
1 vote
0 answers
39 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 ...
Vanessa's user avatar
  • 21