Questions tagged [sun]
The Sun is an almost perfectly symmetric yellow dwarf star [spectral class G2V] which is at the center of our Solar System.
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Why the gravity of a black hole is so strong by the Bad Astronomer
In this bad astronomer video, Phil Plait says two things:
1) He first demonstrates the effect of gravity using paper, and he keeps a fixed mass and distance. However as he makes the paper smaller and ...
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35 views
Is the surface temperature of the sun constant?
I was just wondering that during the suns mains sequence would it maintain a constant temperature at the surface and only cool once the hydrogen in its core runs out, or is it always slowly decreasing?...
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2answers
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Calculation of the temperature of the Sun's core? Why is this value so low?
From the Stefan-Boltzmann Law ($j^*=\sigma T^4$), the luminosity of the Sun is $L_{sun}=j^*A=[\sigma T^4][4\pi R_{sun}^4]=3.85\times 10^{26}$ W.
If I assume the Sun to be in a steady state then the ...
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2answers
51 views
Is an obsidian plate safe to use as a Sun viewer? [closed]
Is a 0.5 cm thick obsidian plate good to see the Sun directly?
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1answer
42 views
Can RGB screen color exist in real physical world?
For example the bright royal blue color; R0 G10 B220, HEX: #000ae1. I know this color cannot be printed nor painted. But can this blue color exist in the real world other than on a digital screen? For ...
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2answers
50 views
Size of iron sphere with mass of our sun [closed]
What would be the diameter of a sphere of iron with the mass of our sun? Use standard density of metalic iron.
I realize it would then collapse into a star in its own right and become much smaller as ...
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1answer
131 views
What exactly is delta-14C and why are there periodic plateaus in the delta-14C curve?
I downloaded the IntCal13, IntCal09, and IntCal04 datasets (parent site), and when I plotted the last 24k years was surprised to see a plateau or even reversal appear every ~5300 years. Apparently we ...
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1answer
114 views
Where is nuclear fusion occuring in the Sun?
My understanding is that the sun is basically a sphere of hydrogen with a helium core, and that the hydrogen is undergoing nuclear fusion to produce helium.
There are many images and cross-sectional ...
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3answers
76 views
Radius of the Sun
Is it possible to calculate the radius of the sun with minimal amount of physics?
I couldn’t find resources on the internet that gives me an answer using a theoretical formula.
You are given values ...
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2answers
67 views
What is the reason for the emission of electromagnetic waves from the sun? [duplicate]
What is the reason for the emission of electromagnetic waves from the sun and why curve its in about the visible light is maximum?
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2answers
70 views
How much change in Earth's orbital distance to change average temperature by 1°C?
How much closer/farther would the Earth need to be to/from the Sun to effect a $1 \sideset{^{\circ}}{}{\mathrm{C}}$ increase/decrease in average temperature?
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Is it possible to approximate the solar radiation output for each hour of the day with the total output in a day?
If you know the total irradiance received by the sun during a single day, could you approximate how many irradiance each hour you get if you assume it was a clear day?
I am able to calculate the ...
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3answers
78 views
Is there a difference between the red sky in the morning and in the evening?
It certainly has a different feeling to it, but
does the temperature or earth's rotation or the clouds
or anything else really make it two different physical
phenomena or at least different colors?
...
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1answer
30 views
How much does time-dilation effect our observance of the most massive objects in our solar system?
Disclaimer: I'm kind of a newb, so I apologize if this question is not well formed. Please comment if anything is unclear, and I will do my best to make corrections.
Reading this post about time ...
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1answer
91 views
How many times do solar protons repeatedly fuse and fission before they form deuteron
In the proton-proton chain reaction in the Sun, the first step is
$$p + p \rightarrow \; ^2_2{\rm He} .$$
After this, the most likely thing to happen next is that the reverse reaction occurs: the $^...
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1answer
36 views
If the Sun had a larger surface temperature how would that affect its appearance to us in the sky?
I thought about this when I came across wiens displacement law which says the higher the temperature, the lower the peak wavelength. If the sun was a lot hotter, and its peak wavelength wasn't in the ...
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1answer
54 views
How much does temperature affect the time of sunrise?
Please forgive me if this is a dumb question, or if my understanding of basic physics is wrong. Please feel free to correct me.
As I understand it, if the Earth didn't have any atmosphere, then the ...
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0answers
27 views
What is angle between ray to center of the sun and its perimeter?
If I took a ray from a point on the earth P to the center of the sun. And another ray from the same point on the earth to the perimeter of the sun. What would the ...
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1answer
62 views
Will a black body placed somewhere around the Sun obtain (eventually) the same temperature as the Sun?
Suppose we look (above the Earth's atmosphere) at the wavelength ($=\frac c f)$ spectrum emitted by the Sun:
This shows that the Sun is approximately a black body with a temperature of about $5525(K)....
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1answer
73 views
Question about China's Artificial Sun
I have read recently in many websites dedicated to science that China has made an artificial sun hotter than the 'sun'. My question is how did they make a thing that can withstand such a high ...
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1answer
43 views
How does the Earth's radial acceleration affect it's velocity during orbit around Sun? [closed]
When the earth moves along its ellipse at $67,000mph $ it accelerates at $0.006m/s^2$ would it be correct to say it's speed at some points relatively increases by $0.006m/s$ every second
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1answer
55 views
What's the Earth's linear acceleration component around the Sun?
The earth's centripetal acceleration around the Sun is $0.006m/s^2$ does this mean one can say the earth's acceleration when it travels(revolves) at $670,000mph$ is simply equal to its centripetal ...
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0answers
19 views
How does brightness affect color? [duplicate]
How does brightness affect the color of light? For instance, the sun might be yellow because of the blue scattering when the light travels through the atmosphere - but if you look at it, it seems ...
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2answers
111 views
Why does the sun always have some whiteness? [duplicate]
So the atmosphere scatters light on its way to earth, making the color of our sky. For example, when the sky is blue on a clear, sunny day, the sunlight appears somewhat yellow because the blue light ...
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1answer
70 views
How does Sun's fusion output compare to its gravity?
How does the total solar energy output compare to the total energy required to keep it contained (i.e. Sun's total gravity).
In other words, is Sun's output "positive" if its gravity is factored in ...
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1answer
40 views
What is the incident power of the sun for different parts of the U.S over time?
I have seen number as low as $200\ \text{W}/\text{m}^2$ to $1000 \text{W}/\text{m}^2$.
I'm in California and looking for information on how much power my solar panels will pick up.
I have $4100\ \...
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1answer
57 views
Is the Earth orbiting an 'illusory' Sun, owing to the 'speed' of gravity? [duplicate]
We see the Sun about eight minutes after light left it. Presumably this means we are also experiencing the Sun's gravity 8 minutes after it 'left' the Sun.
So are we orbiting around the Sun we can ...
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1answer
86 views
Does the sun have nonzero electric charge? [duplicate]
The sun is a star, meaning it's a ball of gas undergoing nuclear fusion in its core. The sun, like any other star, experiences line-driven stellar winds due to the transport of ions from its interior ...
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2answers
40 views
How does the energy of a solar flare propagate?
Does it radiate outward, spherically, or is it more directed? Is there some opening angle? Is it more complex than this?
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1answer
54 views
What's the eccentricity of our sun's orbit around the center of the galaxy? [duplicate]
Just thinking about "galactic habitability zones." Is this even a valid question?
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3answers
2k views
How massive is the Sun compared to other stars?
I was just reading "Rare Earth" by Peter Ward and Donald Brownlee and they claim that $95\%$ of stars are less massive than the Sun. But, I was always told the Sun is an average star. Which is it?
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0answers
25 views
If the Earth would change into a ball of water, how wil its form develop, considering only the Sun's and Moon's influence? [duplicate]
Let's fantasize that the Earth changes in a non-rotating ball of water. And let's assume the only gravitational influences on it are those of the Sun and Moon.
What will happen to the form of the ...
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3answers
82 views
How to calculate weight of an object orbiting another object?
How do we calculate weight of an object which is orbiting another bigger object in the space?
For example, comparing the pair of Sun-Earth, Earth is orbiting Sun due to the force applied by Sun on ...
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1answer
27 views
Gravitational/electromagnetic effect of planets on solar activity?
Does the gravitational and/or electromagnetic influence of planets have any effect or correspondence to solar activities (e.g. solar flares/CMEs) - and if so, does the planetary position (where they ...
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2answers
80 views
Why are clouds lighter than the sky during the day but darker at night
This is probably a very basic question but I couldn't find a good answer to it, most search results are about rain clouds or clouds appearing red at night (something I've never seen except for during ...
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1answer
36 views
Triangulating Sol's position from another star
Let me pose this question as a hypothetical.
Your ship makes a warp/jump through space. There's a malfunction. You're definitely not at your intended destination. You've warped to an unknown star, ...
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1answer
63 views
Living at the equator (Colombia), how to figure out the orientation towards north using the sun falling through a window?
The real life issue is this:
A friend is moving to a new apartment. What is bad here, is if the apartment is getting full sun in the morning or afternoon. So the Sun goes from east to west, right? If ...
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3answers
83 views
Ray sun heating
I recently got a curious question about the sun rays. Is there a material that can absorbs most of them and turn it into pure heat?
For example, we all know that dark material (black t-shirts) get ...
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1answer
339 views
Why are there dark lines in an absorption line spectrum from the Sun? [duplicate]
Consider this image and quotations from Basics of Radio Astronomy for the Green Bank Telescope:
When a continuous spectrum is viewed through some cool gas, dark spectral lines
(called absorption ...
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1answer
168 views
What would happen if gamma-ray burst from a supernova burst hit the sun? [closed]
What would happen if gamma-ray burst from a supernova burst hit the sun? Would the sun explode? Would the sun expand. Have a longer lifetime? Shorter Lifetime? Because people are nit-picky about stuff ...
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1answer
79 views
What is meant by “stable/unstable to convection” in the context of the solar atmosphere?
In studying the Schwarzschild stability criterion (for the solar atmosphere); $$\left\lvert\frac{dP}{dr} \right\rvert\lt\frac{\gamma P}{\rho}\left\lvert\frac{d\rho}{dr}\right\rvert$$ From my notes are ...
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4answers
71 views
Is there any way looking at Stars from that I can understand that we are revolving around the Sun?(Not caring about other planets for now)
I am learning Astronomy. I videos or lessons I look at are already biased over heliocentric math to explain the parallax concept. I am looking for an intuition to get myself a deeper understanding of ...
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2answers
85 views
Is the reason the sunshine is 'extra bright' after rain due to refraction of the additional water in the air?
Quite frequently after the sun comes out after rain I experience a 30 minute period where the sunshine is 'unusually bright'. Such that it makes my eyes water.
My question is: Is the reason the ...
2
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1answer
114 views
Why does the gas in Sun's outer layer not expand?
Since in the outer part of sun it consists gases. Why don't the gases expand due to heat? This was asked by my friend. And he said that the gases are attracted by the plasma layer by a force. So the ...
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1answer
63 views
Some Rayleigh Scattering questions
Last week I've heard about Rayleigh scattering for the first time, when the classic 'why is the sky blue?' question has crossed my mind and I must admit that it is fascinating!
However, I do have a ...
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2answers
51 views
What if the luminosity of Sunlight increased by 10% [closed]
If the luminosity of sunlight increased by 10%, would people be able to survive outside? Would such brightness of light be very harmful to them, for exemple as much as the Mercury Vapour Lamp without ...
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0answers
26 views
Radiative Forcing
In a first approximation the radiative forcing $RF$ is related to the temperature change by the linear relation
$$
\Delta T = \lambda \, RF
$$
where
$$
\lambda\approx 0.8 \, \frac{{\rm K}}{{\rm W}/{\...
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1answer
281 views
What is the difference between granulation and supergranulation in the Sun's photosphere?
Granulation and super granulation seem to be some sort confused topics as they are due to the heated particles coming out of the surface. What is the difference between the two?
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1answer
140 views
Speed of sound at the Sun surface [closed]
The gas velocity at the Sun's surface is subsonic and At 1 AU from the sun, the solar wind is supersonic. Like Parker wind solution.
Why the velocity at the Sun's surface is subsonic?
(In the ...
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1answer
69 views
What is an active region in sun's photosphere? Why sometimes there is an active region but no sunspots?
What is the theory behind an active region? If we check data in solar monitors, there are some cases where there is no sunspot but there is still an active region.
Why is that the case?
