Questions tagged [the-sun]

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

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35
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 ...
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0answers
42 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, ...
2
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2answers
35 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
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0answers
27 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
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1answer
95 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 ...
2
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0answers
61 views

Could the magnetosphere of Mercury protect humans? [migrated]

In theory, we built a space station orbiting Mercury like the ISS on Earth. Will the magnetosphere of Mercury similarly protect humans from this radiation (despite being close to the sun)?
1
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1answer
53 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
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1answer
120 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
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2answers
176 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
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1answer
48 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 ...
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2answers
156 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 ...
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1answer
96 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
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1answer
122 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
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0answers
68 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 ...
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1answer
85 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
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1answer
836 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?...
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1answer
87 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
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1answer
85 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?...
19
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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
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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
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0answers
40 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
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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
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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 ...
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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
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2answers
293 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
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2answers
236 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
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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 ...
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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 ...
45
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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?
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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
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1answer
59 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
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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 ...
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0answers
79 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
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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
70 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
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1answer
136 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
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1answer
33 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
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1answer
106 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
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1answer
97 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
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1answer
133 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
65 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 ...
3
votes
2answers
118 views

Is the equinox absolutely true east everywhere?

I've read that only only in the equinoxes do you get to see the sun rise in the exact east regardless where you might happen to be. However I think this is not absolutely true everywhere, but only in ...
11
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1answer
2k views

Replenishing hydrogen in the core of the sun

How is hydrogen supplied to the core of the sun? Shouldn't the radiative zone prevent this? Shouldn't heavier helium fill the core? How much of the hydrogen can the sun fuse?
3
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2answers
1k views

Can you provide a visual description of the sun rise?

The Sun rises in the east only two times a year. The other days, the Sun rises in the east, but a little bit to the north, or to the south. How can you know the degree of how much north or south it is?...
3
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0answers
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 ...
2
votes
1answer
55 views

How close would the sun have to get to a supermassive black hole to have Jupiter stripped and slingshot into interstellar space?

Please make whatever assumptions are needed. Assume sun approaches black hole on some sort of hyperbolic trajectory. Assume size of supermassive black hole is same as the one at center of our galaxy....
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0answers
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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0answers
67 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?
60
votes
2answers
11k views

Is it dark inside the Sun?

This might sound like a strange question, but something got me thinking about it recently. The opacity of plasma in stellar interiors can get quite high, making for shorter free-paths for photons. In ...
2
votes
0answers
121 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 ...

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