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.

Filter by
Sorted by
Tagged with
0
votes
2answers
90 views

Stars with same colour

This is the problem I'm trying to solve. When it says they have the same colour, does that mean that they have the same temperature?
1
vote
2answers
1k views

What are the differences between light from the sun and light from a laser?

The sun and the laser both give off photons, but there is clearly going to be a difference(s) in the light I receive from both sources. What are those differences (energy, intensity, orientation of ...
-4
votes
1answer
492 views

Gamma ray energy efficiency

How could we collect energy from gamma/x-rays instead of visible light which can be millions of times less efficient (compared to gamma/x-radiation)? Since ...
6
votes
2answers
1k views

Why does the temperature of an object rise to a certain level and stop under sunlight?

Suppose we put a jar in front of a lamp (which mimics sunlight) and wait for the jar to heat up. When the temperature of the jar increases by few degrees, it stops increasing. My thought is that as ...
11
votes
3answers
369 views

Why aren’t sunsets red when viewed from low earth orbit?

So “Why are sunsets red?” seems to be a pretty common question and it has to do with Rayleigh scattering in the atmosphere. I’m following some game dev tutorials (example implementation) on how to ...
1
vote
2answers
115 views

what is meant by solar spectrum?

How can we get absorption lines in solar spectrum instead of emissions lines at such high temperature? Is solar spectrum contains emission lines?
0
votes
1answer
1k views

How do I estimate the probability of a Carrington-level coronal mass ejection (CME) hitting the Earth?

I have seen some material which estimates the probability of Earth being struck by a Carrington-level CME over some time into the future. These estimates seem to be derived from historical data of CME ...
1
vote
5answers
411 views

Does the sun have both types of angular momentum?

Does the sun have both types of angular momentum, 1. spin angular momentum 2. orbital angular momentum?
1
vote
2answers
2k views

Does the sun have angular momentum?

The sun was formed like this: Clouds of dust and gas were moving and so this cloud of gas and dust pulled together its particles by the gravity of these particles. Since this cloud used to move in ...
33
votes
6answers
17k views

Is the light from the Sun the same as the light from a bulb?

I'm arguing with a friend of mine on whether the light emitted from the sun is of the same type of that emitted by a bulb. Her insistent ignorance is laughable, unless I'm wrong... She's talking ...
1
vote
0answers
50 views

Sun constant formula derivation using Kepler's laws of planetary motion [duplicate]

Well, my previous question was re-asked at the Mathematics StackExchange. It was about the derivation of this formula: $$\text{G}_\text{sc}\left(\text{A}\right)=1367\cdot\left(1+0.03\cos\left(\frac{...
4
votes
0answers
365 views

Don't we know how the magnetic field of the Sun is created?

This is how Wikipedia explains stellar magnetic fields: Stellar magnetic fields, according to solar dynamo theory, are caused within the convective zone of the star. The convective circulation of ...
4
votes
1answer
274 views

Color of sun during sunset on moon

I just learned that sunset on earth is orange because of the Rayleigh Scattering effect. The dust particles in the atmosphere scatters the sunlight during the sunset. However, since the moon has no ...
-1
votes
1answer
347 views

Coronal heating problem -How deep does it go?

On the top of the list of problems in solar physics we find the coronal heating problem. The Corona is the outer plasma atmosphere of the Sun, with a temperature of 1-5 millions of degrees Kelvin, ...
-4
votes
1answer
197 views

Hydrogen fusion in the Sun-neutrino

One of the ways nuclear fusion happens in the sun is deuterium and tritium fusion which forms a Helium-4 atom and a neutrino. What flavor of neutrino is created - a tau, muon, or electron neutrino?
2
votes
1answer
52 views

Sun's photosphere slowing down

In this video https://www.youtube.com/watch?v=IbpiovW507M I heard that the sun's photosphere is slowing down because photons from the sun's core hit it. But wouldn't the other layers of the sun slow ...
21
votes
3answers
6k views

Why do materials change color when exposed to the sun for a long time?

I have a lot of solid objects that were exposed to the sun for many years and "obviously" they changed their color. I write obviously because I know it empirically and from other people, but what is ...
35
votes
6answers
10k views

If the moon had a mirror surface, would the earth be equally illuminated as by the sun during full moon, or would it require a different mirror shape?

Suppose the apparent diameters of the sun and the moon are exactly the same (which in fact very close to the real situation). If the moon had a perfect mirror surface, would the reflected visible ...
1
vote
1answer
179 views

Tunneling for hydrogen fusion

So I'm trying to find a rough estimate of the temperature required for Hydrogen to turn into Helium through quantum tunneling. In the lecture we were presented with the following: $$\frac{p^{2}}{2\mu}=...
2
votes
2answers
2k views

Sun constant formula derivation

In a book, I've to read for a class at my university, called 'Duurzame Energietechniek' (Dutch, translated: renewable energy) they gave a formula that looks like: $$\text{G}_\text{sc}\left(\text{n}\...
55
votes
1answer
4k views

What causes the Sun to appear to be in front of a building in this picture?

I took this photograph a few days ago, during sunrise, using my smartphone camera and digital zoom: It seems that the sun is in front of the building. How is this explained?
1
vote
1answer
3k views

Moon vs Sun size and distance 400 times

I have seen below statement, and it doesn't sound right: The Sun and Moon seem to have the same size because of this amazing coincidence: the moon is 400 times smaller than the Sun and 400 closer ...
0
votes
1answer
632 views

Apparent size of sun

During a morning walk when I see Sun rising in the east it is quite large. Why? It is known that in the morning sun is at a greater distance than that in noon, so why it is larger? and red?
-3
votes
1answer
233 views

Paradox about the arrival of light from the Sun to our Earth

I recently watched a documentary which said that the sun is 8 light minutes away from the earth. I know that at the rise of the sun we actually see it a few minutes ago, say 2 minutes before it is ...
9
votes
1answer
1k views

When was today's radar measurement of the Earth-Sun distance made and by who?

I have seen other similar questions and someone mentioned radar measurements made in the 1960's. Who did that and when and where? I am not interested in ancient measurements. Only the currently ...
1
vote
3answers
1k views

How does the sun really produce light in terms of waves?

Electromagnetic waves are caused by changing electric and magnetic fields, and these are caused by a charge possible oscillating like an antenna or a varying current etc. My question is, with the ...
1
vote
1answer
412 views

Are coronal hole magnetic field lines open?

It is often said that the plasma exiting the coronal hole (of the Sun, obviously) follows the open magnetic field line. E.g. a direct quote: "Coronal holes are regions of low-density plasma on the ...
0
votes
1answer
573 views

How much Sun is expected to curve spacetime? [duplicate]

Is there any proper way of calculating that how much a space time will curve for any object.
3
votes
3answers
160 views

Is it possible to cook meat using starlight and multiple magnifying instruments

So you can burn a piece of paper with magnifying glass and sunlight. Light from stars are similar to that emitted by the sun, just much, much weaker. Theoretically, is it possible to cook a thinly ...
40
votes
3answers
8k views

Why wouldn't the part of the Earth facing the Sun a half year before be facing away from it now at noon?

The Earth takes 24 hours to spin around its own axis and 365 days to spin around the Sun. So in approximately half a year the Earth will have spun around its axis 182.5 times. Now take a look at the ...
55
votes
8answers
12k views

Is it possible to send all nuclear waste on Earth to the Sun?

If we neglect the danger of unsuccessful lift-off of the rocket and the cost, would it be physically possible to send all nuclear waste on Earth to the Sun? Will there be an obstacle that prevents ...
20
votes
4answers
10k views

How come the Sun's gravity can hold distant planets in orbit, but cannot rip humans off Earth?

The sun is strong enough to keep gas giants close, but why not people?
2
votes
2answers
392 views

Solar prominence

I'm preparing for an upcoming school speech about solar flares and am wondering whether or not the "loop" in the following video is an example of "solar prominence" and what will eventually result in ...
2
votes
1answer
335 views

What does this symbol $\odot$ mean?

While reading through a physics textbook, I came across the use of sub-scripted ☉s. Here's the context: Stars between 0.5M☉ and 10M☉ will evolve into red giants... I'm assuming it's to do with the ...
0
votes
1answer
87 views

Will 100 km body impact with Sun produce burn for people on Earth?

I think yes, but I need someone to look and check my reasoning: If 100 km size body will fall on the Sun it would produce the flash 1000 times stronger than the Sun’s luminosity for 1 second, which ...
1
vote
2answers
121 views

Is an ionized hydrogen a boson or fermion? Does that mean the Saha equation is capable of describing a compound of both bosons and fermions?

My teacher asked me to calculate the ratio of hydrogen atoms in the chromosphere $(T=6000K)$ at $n1, n2, etc$. energy level, so I think I'll have to use the Saha equation. Is my intuition is correct? ...
6
votes
1answer
428 views

How does the 11-year solar cycle alter the cosmic ray flux?

Looking at a flux vs. time graph of secondary cosmic rays (e.g. from a neutron station: www.nmdb.eu/nest/search.php can plot you some. I just tried for example Moscow, from 14 Oct 1951 to today, ...
-2
votes
4answers
694 views

Why do Moon have different shapes/phases on the night sky but Sun doesn't?

We know that each day the shapes/phases of the Moon differs from its previous day and it is periodic with a period of 29 days. So, why it isn't the case in Sun? Or why do we have these different ...
21
votes
7answers
4k views

What can we deduce by the fact that mirrors cannot get a ray hotter than Sun's surface?

I think it is quite counter-intuitive that some lenses or mirrors focusing sunlight to a single spot cannot produce a temperature higher than Sun's Surface. What could a scientist deduce from that ...
2
votes
0answers
92 views

Why the radiative zone of the sun rotates uniformly, while the convective zone of the sun rotates differentially?

Wikipedia says this about the tachocline This is a region where the sharp regime change between the uniform rotation of the radiative zone and the differential rotation of the convection zone ...
8
votes
4answers
4k views

How do neutrinos pass through the sun so quickly?

If it takes thousands of years for light to escape our sun then how can neutrinos generated in the very center of the sun reach earth in just 8 minutes? Why is their speed so great that they can ...
26
votes
3answers
3k views

What causes our Sun to oscillate around its mean Galactic orbit?

According to this answer on Astronomy.SE, The Sun executes oscillations around its mean orbit in the Galaxy, periodically crossing the Galactic plane. I borrowed this illustration (not to scale!) ...
0
votes
2answers
675 views

Why is the moon not full?

Was out running this morning and noticed the both the sun and the moon in the sky. The part that has me stumped is that both the sun and the moon were up at around 60 degrees relative to the horizon ...
2
votes
1answer
625 views

Why do only red dwarf stars have convective currents?

Stellar models indicate that red dwarfs less than 0.35 M☉ are fully convective.[3] Hence the helium produced by the thermonuclear fusion of hydrogen is constantly remixed throughout the star, avoiding ...
2
votes
3answers
200 views

why do hypergiants shed mass before death?

I'm reading on this website here and will be using lots of quotes from it. Hypergiant Star Seen Shedding Mass Ahead Of Explosive Death As Supernova Astronomers using a telescope in Chile have ...
14
votes
2answers
413 views

How long does a positron last in the Sun's core?

Kicking off of this question, I have a short follow-up. The fusion of hydrogen into helium in the Sun's core requires the emission of two positrons per final helium nucleus, because we start off with ...
9
votes
1answer
981 views

How does our sun create positrons in it?

How does our sun create positrons? And does the sun emit said positrons after their creation? I read that the sun creates positrons at it's center but I couldn't find how they form. Is it a ...
1
vote
2answers
971 views

Calculating Temperature Inside Greenhouse

According to this forum I can calculate the internal temperature of a greenhouse with the Stefan-Boltzmann Law via the following variables: Outside Temperature 273.15K Solar Radiation 1000 watts ...
-1
votes
1answer
114 views

Joules of Energy Striking a Window Sill Daily [closed]

Roughly how many joules of energy (through sunlight) will strike a 20 centimetre tall cylindrical bottle on the 10th floor of a building daily, if the bottle is placed on a window sill facing the East?...
3
votes
1answer
103 views

Could heat detected from Jupiter's red spot explain the temperature of the Sun's corona?

This is an excerpt from BBC Infrared Telescope, published 27th July 2016 Jupiter's Great Red Spot - a hurricane three times bigger than Earth - is blasting the planet's upper atmosphere with heat, ...