Questions tagged [the-sun]

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

Filter by
Sorted by
Tagged with
21
votes
5answers
4k views

Was the Geocentric Model correct at all?

It's easy to find resources stating that the heliocentric model is right and geocentric is wrong. But how wrong was it? Was it correct in any way? It was built on incorrect assumptions, but despite ...
6
votes
1answer
85 views

Why is the sunset at different times at the same longitude at equinox?

I happen to live in two places that are literally at the same longitude but several thousand kilometers apart from each other (~47°N and ~68°N). It's just a few days until equinox - and I assumed that ...
16
votes
3answers
778 views

Problem regarding the absorption lines of the sun

Some of the wavelengths of light that are emitted from the sun will be absorbed by atoms in the outer layer of the sun and also the atmosphere of the sun, and we see this as absorption lines in the ...
15
votes
1answer
1k views

When did scientists discover that the Sun has a life cycle and that it is going to die?

I have been researching the history of scientific studies about the the Sun. However I have been unable to find out much information about how the scientific consensus started forming around stars' ...
4
votes
1answer
572 views

Why is 3GHz the best frequency at which to measure the sun's microwave output?

I have read that 3GHz is the best frequency at which to measure the sun's microwave output, but that measurements are made at 2.8GHz for historical reasons, however I can find no explanation of why ...
1
vote
0answers
24 views

How to calculate emission measure from EVE data? [closed]

I am trying to analyse solar flare temperatures from EVE FITS files in PYTHON. All I have are the irradiance values for a range of wavelength at every 10 seconds. I have made clear Gaussian fits to ...
1
vote
1answer
77 views

If the sun is a second or third generation star, where is the neutron star? [duplicate]

It is widely believed that before the Sun was another star, more pristine in its composition (mostly Hydrogen and perhaps some Helium). And maybe before it was yet another. This blog explains this via ...
6
votes
2answers
246 views

How to retrieve from NASA Horizons site the needed data to plot analemmas for other planets?

I posted such a question in space.stackexchange ( https://space.stackexchange.com/questions/46077/which-are-the-correct-input-parameters-for-nasa-horizons-query-to-get-the-right?noredirect=1#...
3
votes
1answer
81 views

Surface of the Sun, or Jupiter, etc [duplicate]

I keep hearing and reading statements that refer to the "surface of the Sun" (how hot the surface of the sun is) or the "surface of Jupiter" (when the Shoemaker comets hit Jupiter)....
1
vote
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 ...
36
votes
5answers
4k views

Why can't we see Saturn's phases from earth?

In the Astronomy Picture of the Day from August 8, 2020 ("Crescent Saturn"), the caption states From Earth, Saturn never shows a crescent phase Why is this? We can observe phases on ...
4
votes
0answers
46 views

Why is our heliosphere an asymmetric croissant shape?

The big, recent astronomy news about our heliosphere's asymmetric croissant shape has me confused.... Some articles mention the influence on our solar system's outermost boundary of very hot cations, ...
3
votes
2answers
43 views

Corresponding values for the Sun's ultra violet color maps?

In my laboratory, we have an antenna to get data from the GOES-16 satellite and I want to reproduce NASA's nice visualization of ultraviolet images from the sensor SUVI. I can read the data without ...
1
vote
0answers
28 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 ...
0
votes
1answer
109 views

Possible Reason for the “NASA UFO sighting: Alien ship 25 TIMES size of Earth spotted near the Sun” news (does it fake or …?) [closed]

I have this news: NASA UFO sighting: Alien ship 25 TIMES size of Earth spotted near the Sun and tried to find the NASA site link by this link, but not found that news , so like to know what could be ...
1
vote
1answer
55 views

How much solar UV radiation would someone get who were on the surface of Titan?

The Saturn system is about 10 times as far from the Sun as the Earth. This question is concerning Titan for two reasons: Titan has an Earthlike atmosphere so you don't have to account for a higher ...
4
votes
1answer
129 views

Is there evidence for galactic “seasons”?

The Solar Year has huge effects on our climate, and the signs of passing seasons are physically evident on Earth. I recently learned about the Galactic Year. To my understanding, our sun orbits the ...
4
votes
2answers
180 views

Is there a connection between the solar wind and the cosmic radiation?

Cosmic radiation consists of high-energetic particles, mostly protons, that come amongst others from supernovae and our sun, right? The solar wind also consists of charged particles, like protons and ...
3
votes
1answer
50 views

Closest stable orbit about the sun of an asteroid?

What is the closest perihelion an asteroid in stable orbit could have? Is there a limit defined by orbital mechanics or could an object be in stable orbit, only too close that melting or sublimation ...
2
votes
2answers
159 views

If the Sun's trajectory were altered, would the solar system follow?

I was reading a text state that the sun is not stationary: "it orbits the Galactic center once approximately every 226 million years as the galaxy spins which is also traveling through space ...
1
vote
1answer
108 views

Sunrise and Moonrise time are same [duplicate]

I checked an app and saw that today, the sunrise and moonrise time are almost same. The sunset and moonset time are also same. Why does this happen? I have always known that moon rises at night and ...
3
votes
1answer
123 views

Why didn't we see those campfires on the Sun until now?

What is it about its optics and instrumentation (aperture, sensors, filters), being in space and distance from the Sun on 30 May 2020 that allowed Solar Orbiter's HRIEUV telescope to see something ...
3
votes
0answers
69 views

What could be the cause of solar “campfires”?

NASA/ESA Solar Orbiter mission just released its first images. They show an ubiquitous feature: miniature flares called "campfires", much smaller than solar flares. (click to enlarge) A ...
1
vote
1answer
86 views

At what distance wouldn't the Sun cast a visible shadow anymore? [closed]

How far from the Sun would a (dwarf) planet have to be so that the Sun is dim enough that it doesn't cast a shadow when you're standing on the planet? What magnitude is the border in brightness beyond ...
7
votes
1answer
847 views

Could the Sun and our Solar System one day leave our galaxy?

I have now learned that the Sun is not fixed in place, so I asked myself this question: It is possible, that the Sun and our Solar System will one day leave our galaxy? If yes, how, and if no, why not?...
-1
votes
1answer
90 views

Why is the position of the Sun so fixed? [duplicate]

Please correct me if I tell something wrong. As we already know, a planet (e.g. Earth) remains on its orbit due to the gravity of the Sun. If the Sun's gravity were not there, the Earth would be ...
1
vote
1answer
86 views

Why the earth orbits the sun from X to -X and not the opposite [closed]

I wonder all the time, why the earth orbits the sun as expected from east to west(X to -X) ? It could be different, for example from the west towards the east . What would happen if that were the case?...
20
votes
3answers
5k views

When was it worked out/discovered that our sun can't go supernova?

As the title says, when did we realise with reasonable confidence that our star is not going to be going out in a supernova blaze of glory? I ask because a while ago I read The Songs of Distant Earth ...
6
votes
1answer
110 views

Is the gravitational field of the sun uniform?

I understand that rocky bodies in the solar system all exhibit gravitational anomalies. Does the sun exhibit any gravitational anomalies? If so are they distinct enough that it effects the orbit of ...
4
votes
0answers
41 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 ...
12
votes
3answers
4k views

Will just a glimpse (less than a second) of sun during partial solar eclipse damage eyes?

This doubt arised when I thought that on normal days, at least I have observed bright sun while going outside, going to office, in park etc. for less than a second. It happens almost daily. Not ...
2
votes
1answer
40 views

What are the Kinematics / Dynamics behind the motion?

https://www.timeanddate.com/eclipse/in/@8133395?iso=20200621 The link I have attached is a predicted model for the eclipse in my area! I am very much confused about the movement of the moon analogous ...
0
votes
0answers
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 ...
4
votes
2answers
303 views

Can the Sun contain degenerate matter?

Degenerate matter (neutronium) is hypothesized to be very dense and, at a certain amount, unstable - in the sense of collapsing on itself and causing fusion. The result would be a massive fusion ...
7
votes
2answers
239 views

Different times of sunset at the same location due to elevation

Me and my friend were watching the sunset on the same location (at my country the latitude is approximately 40 degrees). I am at sea level and my friend is at an elevation. He observed the sunset with ...
1
vote
1answer
101 views

A Noob's question on declination

The Sun's position at noon is perpendicular to the local x-y plane on the equator during equinox. So the declination of Sun on that day is 0. Today the declination of Sun is close to 23, can this be ...
1
vote
0answers
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 ...
47
votes
4answers
14k views

How did Astronomers deduce that the Sun was not a ball of fire?

Its common knowledge that people used to think that the sun is a ball of fire or molten metal, but when did science start to prove otherwise?
-2
votes
1answer
98 views

What are the necessary steps required for calculating the size of a star? [closed]

Title pretty much says it all. Basically, what exact variables are used, and what steps need to be taken, in the calculation of the size of a star? Preferably, some example data for how a the size of ...
0
votes
1answer
62 views

Position of the Sun in the constellation Pisces around the year 1500

I am reading a book on ancient astronomy and it claims that around the year 1500 the position of the sun, at the time of the spring equinox, was on the tail end of the second fish in the constellation ...
32
votes
10answers
8k views

Why doesn’t the Sun fill the sky on Mercury?

I’ve seen a lot of photos showing Mercury in front of the Sun when it passes by and you can see just how tiny it is in comparison. Here’s a great example: So I’d expect if I was travelling towards ...
1
vote
0answers
80 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 ...
2
votes
1answer
52 views

What kind of halo is this?

My friend sent me a video of a kind of a halo phenomenon and asked me what kind of halo it is. There is a 22 degree circular halo around the sun. But there is also a ring which seems to go ...
4
votes
2answers
79 views

Where is the sun relative to my lunar rover?

I'm a robotics researcher writing orienteering code for a solar-powered lunar rover. I have two similar problems: Given the position of a robot on the moon in lunar latitude/longitude, where is the ...
0
votes
1answer
138 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 ...
1
vote
1answer
34 views

Any active solar X-ray imager in orbit?

NOAA GOES-14 & 15 went very recently in storage mode. With those also went the solar X-ray imagers (SXI), as GOES-16 & 17 do not have such instruments on board. Hence, my question: Are there ...
1
vote
1answer
109 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 ...
0
votes
1answer
122 views

RA and Dec of the Sun at J2000

I'm in the somewhat awkward position of asking something that, despite me thinking there should be hundreds and hundreds of web pages and datasets showing this particular value, I've been unable to ...
5
votes
1answer
136 views

Sun, Moon: Relative Distance from Crescent?

This is more a question about the history of astronomy. It recently occurred to me that you can estimate the ratio of earth-moon and earth-sun distance in the following way: We can look at the ...
3
votes
1answer
69 views

How accurate should sun\moon ephemeris be for calculating eclipses?

I am writing a program to simulate eclipses for about -2000 to 6000. My question is, how accurate does my ephemeris for the sun and moon have to be to get a decent accuracy for eclipses? I currently ...

1
2 3 4 5
13