Tagged Questions
14
votes
1answer
115 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?
1
vote
3answers
133 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?
5
votes
3answers
351 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
0answers
27 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?
1
vote
1answer
99 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?
1
vote
1answer
144 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 ...
8
votes
2answers
615 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 ...
5
votes
3answers
261 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 ...
1
vote
1answer
727 views
What is the relationship between mass, speed and distance of a planet orbiting the sun?
After reading this fascinating story about a new exoplanet, I was wondering about how mass, speed and distance determine a circular orbit of a planet around a star.
Given the mass of the sun and ...
3
votes
1answer
70 views
Does the spectrum of Sol's emission change as it ages?
A follow-up to my earlier question How would one navigate interstellar space? that just occurred to me; albeit on a different tack.
Sol is probably in a state of continuous flux. The change of state ...
4
votes
2answers
153 views
The “official” mass of the sun as unit?
I'm searching for the "official" mass of the sun as a unit in astrophysics.
The mass of the sun can be calculated by:
$M_{\odot}=\frac{4\pi^2\times(1 \ \text{ua})^3}{G\times(1\ \text{year})^2}$
So ...
5
votes
2answers
229 views
Is dark matter really present around the sun?
Recently I read an article that there is dark matter around the sun but if it is so, than why can we see it clearly.
If it is called matter than it shall show some hindrance in radiation we receive ...
2
votes
1answer
148 views
Calculating the time of dawn
Knowing that astronomical twilight (i.e. astronomical dawn) is when the sun is 18 degrees below the horizon, I am calculating the astronomical twilight time this way:
...
1
vote
1answer
88 views
Is there anything special about the Sun's photosphere in terms of density?
The Earth has a definite boundary between rocky/ watery surface and gaseous atmosphere. The same cannot be said of the sun. Even though the photosphere gives an apparent "edge" to the sun via the ...
2
votes
2answers
141 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 ...
1
vote
2answers
458 views
Could a solar flare cause the Earth's magnetic poles to reverse?
With all the hype of the impending "2012 Mayan doomsday" I was thinking it might be interesting to see what principles of physics prevent the theories of doomsday from occurring. One overarching ...
7
votes
2answers
205 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 ...
1
vote
1answer
705 views
Why don't we see solar and lunar eclipses often? [duplicate]
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 ...
4
votes
2answers
343 views
What's the reason for the seasons?
In the diagram, it shows that the fundamental reason for different seasons is when the northern hemisphere is titled towards the sun there's summer in northern hemisphere and winter in southern ...
1
vote
1answer
121 views
How to calculate the amount of night time during a flight?
I have been asked to find a way to calculate the amount of time that a flight takes during night time.
So far, I have the departure latitude and longitude and the time of takeoff, the arrival ...
1
vote
1answer
500 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
5answers
199 views
sun-moon-earth anomaly
When one looks at the sun and the moon in the sky together, why is it that the illuminated crescent of the moon does NOT "point" at the sun?
(More correctly the perpendicular bisector of the straight ...
5
votes
1answer
43 views
Is there an Algorithm to find the time when the sun is X degrees above the horizon for a given latitude B at date C
Is there an accurate algorithm / method to determine the precise time of day/night when the sun is X degrees above (or below) the horizon for a given latitude Y at date Z?
Is this the same question ...
2
votes
1answer
58 views
Get time from sun Azimuth
I want to know if I can determine the time where the sun's azimuth is at a given value.
In other words, I want a function that takes the sun azimuth along with longitude or time zone and outputs the ...
4
votes
1answer
268 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 ...
8
votes
3answers
180 views
Are planetary orbits measured from the Sun's surface or centre?
I would imagine planetary orbits are measured from the Sun's centre and not its surface. Is that true?
I can't find anywhere that actually states this.
5
votes
3answers
497 views
Is a water world possible, and for how long could it be stable?
I have several questions regarding this topic.
First, could a water world be stable for thousands of years with most of its surface remaining covered in water. What would it take for this to be ...
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! ...
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 ...
2
votes
1answer
98 views
Solar Cycle UV Variation
The average energy we receive from the Sun is 1,366 w/m^2, and this only varies by 0.1% from the activity peak to trough of its 11 year cycle. About 9% of the energy comes from wavelengths less than ...
5
votes
3answers
472 views
Why does the light side of the moon appear not to line up correctly with the evening sun?
I live at roughly 52.4,-2.1. On a sunny evenings I've often looked at the moon and the sun and noticed that the light part of the moon does not appear to line up with the sun. For example, at about ...
