Questions tagged [the-sun]

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

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0
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1answer
151 views

Sunrise - from earth - sun position or when sun rays reaches earth?

Time for the sun rays to reach earth is approximately 8 mins. If time of the sun rise is 7:30 - which time is this? Time when sun rays reaches earth or time when earth and sun comes into correct ...
8
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1answer
685 views

Can one detect from earth that angular momenta of its axial rotation and its orbital rotation are “almost parallel”?

I mean that the angle between these angular momenta is acute as opposed to obtuse (23.5 and not 180-23.5), so that the rotations are "roughly in the same direction". Related but distinct question -- ...
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1answer
98 views

What is a “semester series” for eclipse prediction? - Solar saros series 147 and 152

Yet again, I just stumbled across another baffling eclipse question (actually, two now). I was interested in two eclipses (Saros series 147 and 152) that will both be occurring in 2021. Each of these ...
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2answers
210 views

Remains of the progenitor of the Sun

It has been argued that it is not possible to trace back the remains of the progenitor star of the Sun (sometimes called Coatlicue), which, being estimated in the mass range of 30 $M_{\odot}$, should ...
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2answers
217 views

From what distance would our sun have an angular diameter of 7 arc seconds?

If an observer travels away from our sun, at what distance would our sun occupy 7 arc seconds of space?
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1answer
454 views

What is the orbital period of our sun around its barycenter?

In years, what is the time it takes our sun to orbit around our solar system's barycenter?
3
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1answer
80 views

What does it mean that the Sun`s rotation axis is: RA 286.13° , Dekl: 63.87°?

first post here. I found 1 related Question, which has not solved my Problem. SHORT QUESTIONs VERSION: Suns axis is 7,25° tilted from the ecliptic. But in which direction? LONG QUESTION: Nasa ...
2
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1answer
151 views

What is the planet relative to earth that shows the greatest change in apparent brightness?

What is the planet relative to earth that shows the greatest change in apparent brightness? I think the answer is Mars, and a quick google search reveals it is Mars. I have my reasoning here, but I ...
2
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3answers
416 views

Calculate position of the Sun in ECEF

I'm making a very basic orbit simulator in C# using the Helix Toolkit. I want to position the Helix lighting object at the sun, but also be able to calculate solar eclipse by the moon and earth for a ...
4
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0answers
72 views

“Pluto Time” for any solar system body

A while back NASA made a site called Pluto Time, where you can enter your address and find that "...moment near dawn and dusk each day, where the illumination on Earth matches that of high noon on ...
2
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1answer
106 views

How much more atmosphere is the sun passing through at sunset as opposed to at its peak in the sky?

I was looking at the sun during a sunset earlier today and wondered how much atmosphere you need to be able to look directly at the sun without damaging your eyes. The thought crossed my mind because ...
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3answers
70 views

Hypothetically, if our sun was yellow would we still see “white” colours?

Hypothetically,if our sun was yellow would we still be able to see white colour on objects like snow,cotton etc.? Would we have the phenomenon of rainbow?
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2answers
160 views

How do astronomers know when the Sun will die?

How it is possible for astronomers to find out when the end of the Sun's life will be?
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1answer
72 views

What phenomena was this video from SOHO actually showing?

My friend showed me a video of a CME that looked as if it was swirling into a gigantic circular "spaceship" or "UFO" and he explained it as "an alien ship potentially refueling". I did a bit of ...
3
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1answer
118 views

Why does the adiabatic exponent decrease at the ionization zones?

The context is the ionization zones in stellar atmospheres or interiors, the Sun, for instance. The adiabatic exponent is the heat capacity ratio: $$\gamma = \frac{c_P}{c_V} = \frac{C_P}{C_V}$$ And,...
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0answers
58 views

Erratic Sundial

My sundial shows real time until 11am when it will drop behind an hour until sunset. This is in keeping with daylight saving but why does it show real time before 11am? Am I missing something ...
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2answers
134 views

Movement of the Sun in space

Does the Sun undergo any cycles or revolutions approximately every 24,000 years or 8.6 million years? In Hinduism it is believed that the Sun revolves in an elliptical orbit around a large mass at ...
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0answers
35 views

What's the time in which the sun rises? [duplicate]

What's the time the sun takes in order to rise? (The time in which the solar disk crosses the horizon) How does this time depend on local latitude and the sun's declination? Assume that we're at sea ...
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2answers
298 views

How much magnetic attraction is there between the Sun and Earth?

How much magnetism is there between the Earth and Sun? Would the distance from the Sun differ for not the Earth iron core and how much?
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1answer
247 views

Why does the sky look like it has three suns in this video? [closed]

Check out @natalie9280’s Tweet: long story short, friday morning at around 6:40am i looked outside and i saw three suns. i checked to see if there was an eclipse and i could[n't] find anything. ...
2
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1answer
109 views

How would a flat mirror on the Moon reflect sunlight

I was solving a task that said (paraphrasing): There is a flat mirror on the Moon, whose reflection coefficient is 100%, and observers on the Earth observe it as a star whose apparent magnitude is $...
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1answer
72 views

Why is the shadow of the earth not visible during sunsets?

I would imagine that during a sunset, for a brief moment of time, there would be a shadow of the earth seen in the clouds but I have never seen this. Why does it not happen?
26
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3answers
6k views

Where did the Sun get hydrogen to work with if it is in the 3rd generation of stars?

As I see here, the Sun belongs to the Population I group of stars, which is the 3rd generation of the stars in our universe. 1st generation stars are Population III, 2nd generation are Population II, ...
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1answer
37 views

Recognising lunar month only by looking the sky

Suppose somebody went on an island and don't have sense about time, dates, months. The only thing he has is seeing the sky. Is it possible to recognise which lunar month it is by just looking the sky? ...
3
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3answers
1k views

How did the solar system get its angular momentum? Why did Earth not fall into the Sun at the start? [duplicate]

I know that Earth is always falling towards the Sun, but due to its sideways momentum it just misses always. But how did it all start? To go into detail, when the gas cloud with zero angular ...
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2answers
175 views

Why is sunset on 21st of June not the latest?

Why is the sunset not the latest on 21 June, but only on 27 June. Purely geometrically regarding the orbit of the two celestial bodies this should not be like this? Is there somewhere a good source, ...
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1answer
49 views

The total number of solar eclipses in a century repeats roughly every 6th century

We know that on a longer time scale (millions of years) the orbits of planes are unstable and it is impossible to make predictions about eclipses millions of years into the future. But on a shorter ...
4
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2answers
108 views

Is there a name for the star/supernova hypothesized to have been a precursor to the Solar System?

I found an article suggesting a supernova injected debris which helped nudge the formation of the Solar System 4.5 billion years ago. I couldn't find a name for this hypothetical star/supernova after ...
5
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0answers
100 views

Which astronomer set his beard on fire because he left the cap off his telescopes finder?

There is a famous story of an experienced astronomer setting his beard on fire because he left the cap off his telescopes finder. I know it's said to be true of Galileo, but I thing it's relatively ...
2
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2answers
184 views

Old star vs New star

We know that with the passage of time, hydrogen inside (near or at the core) a star is converted to helium and other heavy elements via fusion. We can then deduce that the old sun contains heavier ...
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9answers
11k views

Simple experimental evidence that Earth revolves around Sun

What are the simplest experiments or calculations that give evidence that the earth revolves around the sun? Can you please explain them and reference the history? Many simple explanations such as ...
3
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0answers
70 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 ...
5
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1answer
118 views

How to calculate the time for the solar disk to pass the horizon and transit's lines

For a given date, longitude, and latitude: Popular apps and websites give the time when the sun's center or edge is on the horizon (i.e., the time of sunrise and sunset) or its transit (i.e., ...
4
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1answer
98 views

How to compute the sun's (upper) transit

As detailed in https://physics.stackexchange.com/questions/41450/is-there-a-simple-accurate-formula-for-calculating-transit-times-from-rise-and, the sunrise, and set times can accurately be used to ...
4
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1answer
165 views

How can heavy elements exist when the universe is young compared to the lifetime of a star? [duplicate]

Our sun is said to be incapable of producing heavier elements, and these are thought to originate from older stars dying and going supernova. If our sun is 4-5 billion years old, and has a lifetime of ...
2
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1answer
51 views

How is magnetic field is generated over the sun?

Dynamo theory suggest how magnetic field generated on Earth. Due to flowing magma which contains molten iron generates magnetic field on earth. But how magnetic field is generated over sun?
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2answers
150 views

Is Limb Darkening because at centre we are directly looking core, whereas at limbs we are seeing only photospheric part?

Is limb darkening of the Sun because at centre we are directly looking the core and different zones, whereas at limbs we are seeing only the photospheric part (and less beneath photospheric part)? Or ...
50
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5answers
11k views

Why is moon light not the same color as sunlight?

The light from the moon is light being reflected from the sun. The sun, in space, is white. But on Earth, when the light is filtered through an atmosphere, the light appears yellow. So then, why is ...
3
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3answers
222 views

Will the Sun's solar wind push a permanent magnet out of our solar system?

If you were place a strong permanent magnet into the solar wind, like a 1 inch cube neodymium magnet, would the charged particles of the solar wind colliding with the magnet's magnetic field push the ...
21
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2answers
8k views

Is our sun in a star cluster?

Sorry for the absolute begginer question here, but is our sun a part of some globular cluster? It is something related to Virgo supercluster?
3
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2answers
107 views

Will stars live longer if they consume more hydrogen?

I heard that stars would live longer if they consumed more hydrogen and material from their 'environment'. Is that true? For example, if the sun consumed all of the gas giants, would it live a little ...
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1answer
76 views

Where will the atmosphere of our Earth go if our sun blows it away completely?

What will happen?Will our atmosphere head to the next gravity dominant body?Will our moon hold a part of our atmosphere or is too weak to hold it?Where all those gases are supposed to go?
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1answer
118 views

What types of star do we know are hostile to life (like ours)?

Certainly all stars have enough energy for a planet to host life. But a more magnetically active star is not preferred because solar ejection could strip planets of their atmosphere. What's the right ...
6
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1answer
321 views

Why does the Sun's surface contain lithium?

As far as I was aware, stars don't usually have lithium, but it has been observed that there is plenty of lithium on our star's surface. In addition, a team lead by Garik Israelian took a census of ...
1
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1answer
523 views

How was the distance from the Earth to the Sun determined

How was the Earth to sun distance measured. How do we know how far from the Earth the Sun actually is.
3
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1answer
66 views

Apart from Io, will any Galilean moons have oceans and land if their ice melts

When our sun expands earthlings, if still alive, will have to leave. The Galilean moons offer a lot of water but we would also need land. As far as I can tell there will be no land for earthlings to ...
2
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1answer
43 views

Ancient greeks know about leap day? [closed]

I'm reading about Antikythera machine and its functions. So I read about solar cycle and moon cycle and how they used 19 solar years to compare with 235 lunar cycles. So this is my question: They ...
3
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1answer
148 views

Given sunrise, noon, sunset, longitude and latitude can I calculate the “hight” or “ascension” of the sun?

I'm trying to make a simple app for my own use to be able to check which of my favorit restaurants have outdoor seating sun and for how long etc. Given the data in the title (sunrise, noon, sunset, ...
2
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2answers
332 views

Computation of mean sidereal time at Greenwich using solar position algorithm

Using Equation 28 in Section 3.8.1 of Solar Position Algorithm (Reda, I. and A. Andreas, Jan. 2008), I computed the mean sidereal time at Greenwich for 2003 October 17 for four different times (UT), ...
4
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1answer
139 views

What makes an exoplanet to orbit around its star backwards?And why did we consider our orbital movement to be forward?

I read somewhere that an exoplanet in the name of HAT-P-7B orbits its star backwards.Why? And why did we consider our orbital movement to be forward?Is there some scientific reason to consider the ...