The Sun is an almost perfectly symmetric yellow dwarf star [spectral class G2V] which is at the center of our Solar System.
3
votes
2answers
150 views
How is the sun's equatorial circumference measured?
How is the sun's equatorial circumference measured by scientists?
2
votes
1answer
26 views
How does irradiance behave over time?
I am trying to clarify data on weather from the Royal Netherlands Meteorological Institute (KNMI); I have incorporated the Solar Position Algorithm (SPA), such that I can calculate sunset and sunrise ...
2
votes
1answer
58 views
Calculating the length of day at any time of the year? [duplicate]
Is it possible to calculate the length of the day at various location (distances) from the sun? I hear agricultural scientists are able to do that. To make calculations easier assume there is no axis ...
7
votes
2answers
233 views
Why don't we see solar and lunar eclipses often?
Since we see the new moon at least once in a month when the Moon gets in between of the Sun and the Moon at the night and as far as I know if this happens during the day, you'll get to see a solar ...
5
votes
1answer
307 views
Is there a simple yet accurate formula for where on Earth the Sun and Moon are directly overhead?
I'm trying to improve a site that shows the region of the Earth currently under daylight, and I
need a formula that, given the current time, tells where
(latitude/longitude) the sun and moon are ...
23
votes
3answers
2k views
Why is the sky not purple?
I realise the question of why this sky is blue is considered reasonably often here, one way or another. You can take that knowledge as given. What I'm wondering is, given that the spectrum of ...
2
votes
1answer
53 views
What is the sun's spectral series?
My physics book says that six colors can be distinctly seen in white light: red, orange, yellow, green, blue, and violet. Does solar light only use these six wavelengths and mix them additively, or ...
0
votes
0answers
49 views
How do you estimate colour temperature based on the position of the sun in the sky?
I'd like to estimate the colour-temperature of sunlight (as applied in photography) based on the position of the sun in the sky for a mobile phone app I'm working on (app link from a more appropriate ...
1
vote
1answer
99 views
Does brown but transparent swimming pool water heat significantly faster than western style highly chlorinated pools?
Eastern European swimming pools are often brown tinted water. i was told it was the color of the chemical to keep the pools clean, but who knows. These pools did not smell unsanitary and may have even ...
0
votes
0answers
15 views
How strong a solar flare needs to be to be easily seen on a projected white light image?
The first and the storgest solar flare so far is detected by simply projecting the Sun with optics on a paper. The flare was so intense that it was brighter than the photosphere beneath it.
Nowadays ...
1
vote
1answer
100 views
When should angles be expressed in degrees vs. radians?
I am trying to calculate the albedo of a given latitude by following the methods of Brutsaert (1982), I have copied the formula below:
3.6 Shortwave and long-wave radiative fluxes
Albedo ...
1
vote
0answers
89 views
Could Voyager 1 have entered a solar radiation belt?
We currently believe that the Sun has no radiation belts because the unstable magnetic field, which turns every 11 years, is not stable enough to sustain a solar radiation belt. But observations from ...
14
votes
1answer
116 views
What happens to the electron companions of cosmic ray protons?
If primary cosmic rays are made mostly of protons, where are the electrons lost, and does this mean that the Earth is positively charged?
Does the sun eject protons and electrons in equal number?
6
votes
2answers
143 views
Must a vertical sundial face exactly South?
I am a sundial. I'm prepared to bet
Your watch can't tell when the sun will set
I once heard Frank King talk about sundials in particular this very cool one, which measures Babylonian hours ...
0
votes
2answers
125 views
How can anything be hotter than the Sun?
I've heard that if a space shuttle enters the atmosphere from a bad angle its surface will become so hot that it will be hotter than the surface of the Sun.
How can that be? It seems to an uneducated ...
4
votes
2answers
64 views
Attenuation mass-thickness for sunset light
We are able to look directly at the sun near sunset and sunrise, which clearly demonstrates the fact that our atmosphere attenuates visible light. Let's imagine it follows the typical attenuation ...
5
votes
3answers
288 views
How many percent of the visible light reaching the Earth are from other stars than the Sun?
How many percent of the whole visible light reaching the Earth are from other stars than the Sun?
Is it maybe 0,5 - 1% or is my guess already too much?
I am interested mainly in visible light, but ...
0
votes
1answer
60 views
Do particles in the solar core travel at the same speed as they would in vacuum?
I just read the Wikipedia article on the Sun. The section on Solar Core states
It has a density of up to 150 g/cm3[47][48] (about 150 times the density of water)
Do the particles (atomic, and ...
2
votes
4answers
247 views
Modeling incoming solar radiation
I want to write a model for estimating incoming solar radiation for a specific latitude on earth but I am struggling to find an appropriate source which shows the required equations for doing so. ...
28
votes
4answers
1k views
Does the sun rotate?
As implied from the question, does the sun rotate? If so, do other stars not including the sun also rotate? Would there be any consequences if the sun and other stars didn't rotate? Me and my friends ...
1
vote
3answers
140 views
How old is SUN ☉?
How do we know/calculate the exact age of sun ☉ ? ie. 4.57 billion years. What is the way to calculate it?
-1
votes
3answers
134 views
What cosmic event would cause Sun rising from the west?
I'm wondering what kind of astronomical or geological events would cause the reversal of Earth's rotation. For instance, Is a meteorite passing very close to Earth able to reverse its rotation?
Can ...
10
votes
1answer
123 views
Have general relativistic effects of the sun's rotation been measured?
I was wondering if general relativistic effects of the sun's rotation have also been measured, like gravity probes A and B measured GR effects from the earth.
0
votes
0answers
58 views
Bird clear sky model in matlab [closed]
I am attempting to write a clear sky solar radiation model in matlab following the methods of
A Simplified Clear Sky model for Direct and Diffuse Insolation on Horizontal Surfaces by R.E. Bird and ...
6
votes
2answers
369 views
1
vote
3answers
1k views
How long until the sun cannot sustain human life on earth?
The sun will last, at its current brightness for 9 billion more years. How long until the sun gets burned down to the point where it cannot sustain life on Earth anymore?
Updated: I am more concerned ...
5
votes
3answers
356 views
Why planets are rotating only in one plane? [duplicate]
Since gravity is three dimensional why planets are rotating only in one plane around sun.
0
votes
1answer
37 views
Produciton of EM waves with differing wavelengths
Sun is the major source of electromagnetic radiation. Then if the source is the same, how are different EM waves with differing wavelengths produced?
0
votes
0answers
28 views
What is the formula for calculating the length of any given day (sunrise to sunset)? [duplicate]
In a specific date what law gives us perfect measurements and how will we measure if latitude is given?
0
votes
1answer
55 views
How much energy is needed to curve the space so the Sun will come 1 meter closer to our planet? [closed]
How much energy/work will it take if our planet is:
5.9736×1024 kg
or
3.0×10−6 Suns
to move Sun and Earth 1 meter closer ...
10
votes
2answers
3k views
Why can there be fire in space while there is no oxygen?
The sun is made of fire but fire needs oxygen right? So..
Why can there be flames in space, while there's no oxygen?
Same idea as with the rocket engines of the spaceship, which also produce fire ...
3
votes
6answers
968 views
The Sun Can Make Stuff Hotter Than Itself
We intuitively understand the direction that energy travels -- from the thing with energy to the thing with less energy. That's why the second law of thermodynamics is among the first things you learn ...
3
votes
3answers
66 views
Distribution of each element and molecule as a function of distance from the Sun and as a function of time
Are there any graphs that show the distribution of each element and molecule as a function of distance from the Sun?
And maybe even the time-evolution of each distribution over the solar system's ...
3
votes
3answers
2k views
How fast will the sun become a red giant?
I've read many accounts of our sun's distant fate, but what I've never heard is on what time scale these events occur.
For instance, when the sun runs out of hydrogen, I presume it doesn't just WHAM! ...
4
votes
2answers
115 views
What is the mass distribution within the sun?
Jupiter is roughly 1/1000 the total mass of the sun. To get some idea of what effect Jupiter's gravity may have on the sun I'd like to know the approximate mass distribution of the sun. (i.e) the ...
2
votes
2answers
144 views
Was Sun a part of a binary system?
I've read that many stars and other celestial bodies are found to constitute binary systems where the two bodies spin around each other. But our Sun is one of the exceptions. Could it be possible that ...
4
votes
1answer
670 views
Force on Earth due to Sun's radiation pressure
I have been asked by my Classical Electrodynamics professor to calculate the force that the Sun exerts in the Earth's surface due to its radiation pressure supposing that all radiation is absorbed and ...
3
votes
1answer
115 views
Finding radius of Earth through observation of Sun's motion
The question I'm about to pose is from a physics book I had recently bought. Since I am very interested in physics I am quite keen in understanding how this question can be solved. Before I present ...
0
votes
1answer
76 views
What is the relation between surface area and radiation, if any?
Basically I wonder what happens to emitted radiation by douubling a light e.g. twice the surface area of the sun will emit how much more radiation? 4 times more? Is there a formula?
6
votes
1answer
30 views
Refraction and scattered light for NLCs
For helping with judging NLC candidates (are they NLC or not) I have a set of formulas to calculate the minimum altitude (in km) of the candidate given an observed altitude (in degrees) of the ...
22
votes
4answers
2k views
Why is a new moon not the same as a solar eclipse?
Forgive the elementary nature of this question:
Because a new moon occurs when the moon is positioned between the earth and sun, doesn't this also mean that somewhere on the Earth, a solar eclipse ...
1
vote
0answers
21 views
Rosenberg-Coleman effect
I know only that it states some variations of the Sun's magnetic fields. What is the Rosenberg-Coleman effect specifically?
1
vote
1answer
101 views
If there was no Earth, what would be the acceleration of gravity from here from the Sun?
Suppose there were no Earth to pull us back and we're hanging in the solar system. Assuming no other force of gravity from other bodies, what would be the $g$ from the Sun?
4
votes
1answer
25 views
Are solar physics images of use to the night-time community?
I'm actually interested in cases of cross-discipline data re-use.
I know that the SOHO/LASCO coronographs are used for comet finding, that solar telescopes were used to get information about Venus's ...
1
vote
1answer
153 views
What is the apparent diameter of the sun as seen from earth?
I know this may not be physically accurate.
For my purposes, basically 3D renders, I am assuming the sun rays are parallel rays from an infinitely far lamp. If the sky is clear, what size would that ...
2
votes
1answer
517 views
How to determine day/night based on latitude, longitude and a date/time?
Is there a simple method of determining, given a UTC date/time, whether it is day or night at a given lat/long coordinate?
I am currently using a formula based on a Sunrise/Sunset Algorithm from the ...
8
votes
2answers
654 views
Do photons lose energy while travelling through space? Or why are planets closer to the sun warmer?
My train of thought was the following:
The Earth orbiting the Sun is at times 5 million kilometers closer to it than others, but this is almost irrelevant to the seasons.
Instead, the temperature ...
13
votes
2answers
255 views
Is the length of the day increasing?
In Frontiers of Astronomy, Fred Hoyle advanced an idea from E.E.R.Holmberg that although the Earth's day was originally much shorter than it is now, and has lengthened owing to tidal friction, that ...
2
votes
0answers
24 views
Surface UV exposure with cooler star
If the sun's surface was ~ 4000K (and earth closer to compensate), the UV component of the radiation would be less. However, UV makes ozone via photolysis of oxygen. Also, the stratosphere would ...
1
vote
2answers
660 views
Are dangerous rays emitted during Solar Eclipse?
It is said one should avoid staring at Sun as it can damage the eyes, but it is also said that one should not come out in sun during eclipse as it emits dangerous rays. Is that true? If yes, why?
