Sun Definition and 1000 Threads

This question was asked today in my physics examination. Sun Glasses do not have power. Why? I know that the main function of Sun Glasses is to reduce the intensity of light by polarisation. Therefore there no need for them to have power. Or is it something else.

Dear all, Can only the outter planet form rings? If Saturn were moved very close to the Sun, would it be able to maintain its ring system? I personally don't think so due to the fact the high tmperatures would vaporise a lot of the ice in the ring system but I would like to everyone else's...

Hi, Homework Statement I was just wondering, because the Earth follows an elliptical path around the sun and the gravitational force of the sun on the Earth is towards the sun, would the work done on the Earth be considered positive or negative? Homework Equations The Attempt at a Solution...

Homework Statement The gravitational attraction of the Sun and Moon on the Earth produces tides. The Sun's tidal effect is about half as great as the Moon's. The direct pull of the Sun on the Earth, however, is about 175 times that of the Moon. Why is it that the Moon causes larger tides...

I have no idea where this goes... But I have a question. Say if the sun was big enough to turn into a black hole, what will happen to the earth? Will it stay in the same orbital path or will it be suck in by the black hole? Thanks

Once again I have no idea what my physics professor is asking- I am not asking for direct answers necessarily but any help is much appreciated! http://www.physics.utah.edu/~cassiday/p1050/homework06.html

More sample exam problems... 2) The mass of our sun is ~ 2 x 10^30 kg. The mass of a planet is 6 x 10^24 kg. If the distance between the center-of-mass of each is 100 x 10^11 m, what is the distance in meters from the center-of-mass of the sun to the center-of-mass of the Sun- Earth...

If we could move the Earth, how far away from the Sun would it need to be to maintain a temperature similar to what we have now when it becomes a red giant? How large would the Sun apear in the sky? Would the sky still be blue? Would everything have a red tint to it? I was...

Homework Statement A spacecraft is initially in a circular orbit of the sun at the Earth's orbital radius. It uses a single brief rocket thrust parallel to it's velocity to put it in a new orbit with aphelion distance equal to the radius of Jupiter's orbit. What is the ratio of the...

Hi. I am curious about the following nuclear reaction: \nu_{e} + ^{71}_{31}Ga \rightarrow ^{71}_{32}Ge + e^{-}. Can anyone explain to me why this reaction has an energy threshold of approximatly 0.23 MeV? How does one calculate the minimum energy of the neutrino for this reaction to take...

does the fusion reaction in sun produce neutrons or neutrinos? i read websites of which one is saying neutron is produced but the other one says neutrino is produced..which one is correct..what other things would be produced when hydrogen fuses to produce helium in the core of sun?

does the fusion reaction in sun produce neutrons or neutrinos? i read websites of which one is saying neutron is produced but the other one says neutrino is produced..which one is correct..what other things would be produced when hydrogen fuses to produce helium in the core of sun?

http://www.wdc.rl.ac.uk/wdcc1/papers/nature.html It would be interesting to find out just what this doubling effects if anything. http://www.wdc.rl.ac.uk/wdcc1/papers/nature.html may be this. http://www.economist.com/world/displaystory.cfm?story_id=9071007 or this?

Homework Statement Derive the equation using Newton's Law of gravitation and the equation for circular motion. Homework Equations V = \sqrt{\stackrel{GM}{r}} Where G is the universal gravitational constant, M is the mass of the central body and r is the radius...

Homework Statement What is the acceleration due to gravity of the sun at the distance of the Earth's orbit? Homework Equations law of gravity = Gm/r^2 Sun's Mass: 1.99x10^30 kg, earth-sun distance: 150x10^6 km The Attempt at a Solution ((6.67*10^(-11)) * (1.99*10^30))/...

Is it conceivably possible that our orbit around the Sun is changing? Through unforeseen gravitational forces, Increases and decreases of mass, or the makeup of space itself, can the current way we measure time gradually get to the point where it's completely wrong?

The ratio of the mass of the Earth to the mass of the moon is 84.5. Assume that the radius of the Earth is about 6578.0 km and that the distance between the center of the Earth and the moon is 385815.0 km. Determine the distance of the center of mass of the earth-moon system from the center of...

I read a article describing the normality of the sun. It actually described that the sun is pouring the solar neutrino in less amount then predicted by the theory of particle physics. It is due because the sun is right now "boiled off" i.e. its rate of nuclear burning is decreased. If so then...

What is the capacitance of the sun? semms like a straigtforward question but I can't seem to find any information on what it is. I'm don't know if it has been measured, or if its even possible to measure, but I would have thought a body that big and active as the sun would have an ability to...

I'm having a hard time picturing this in my mind: Calculate the largest possible angle as viewed from Earth between the Sun and a hypothetical planet orbiting the Sun in a circular orbit with a=0.65 AU. Assume Earth's orbit is circular and that Earth and the hypothetical planet orbit the...

Distance from Sun to "outside" galaxy? Does anyone have a general figure regarding the distance from the Sun to the nearest place officially "outside" the Milky Way galaxy? Thnaks.

Hello, Here is my question: Just imagine the sun would stop shining, without exploding. It would just totally disappear without causing harm. How long would human race survive without the benefits of the sun? 10 minutes? 10 hours? 10 days? Could it stand the cold longer? How long would it...

I don't know what forum this belongs in. Move it at will. I have already posted this on the APOD discussion site. Today on the way home from work, I saw a pair of sun dogs. At first I could only see the left one which was in a location where there were some wispy clouds. On the right, I could...

I can "understand" the gravitational pull of the sun on the Earth and the Earth mass effect toward the moon, but what pull the sun? a neophyte.

Homework Statement Using the data on the solar wind given in this chapter, compute the averagerate of mass loss of our Sun(M(sun)/year) from: a)the solar wind b)energy generation Homework Equations possible equations: Energy density =(#density)*(energy per particle)= n*(3kT/2)...

A comet is in an elliptical orbit around the Sun. Its closest approach to the Sun is a distance of 4.5 1010 m (inside the orbit of Mercury), at which point its speed is 8.9 104 m/s. Its farthest distance from the Sun is far beyond the orbit of Pluto. What is its speed when it is 6 1012 m from...

Homework Statement The flux from the Sun above the Earth's atmosphere is about 1370 watts/m^2. This quantity is called the solar constant S and equals pi*f(sun). Use the angular radius of the sun as seen from the Eart to find pi*F , the surface flux of the sun. Homework Equations...

I know that it took approximately 3 minutes for lights to travel from sun to earth. Let say the sun is gone now. Like erased, click-n-drag out of the universe in an instant! So until 3 minutes later, no one on Earth would realize it, because nothing travel faster than light! But, could I argue...

I am not an astronomer or astrophysicist but lately, I have been reading a lot of books to upgrade my knowledge in cosmology. I have encountered two issues that I am baffled about and wonder if anyone can help me throw some light on them (1) If the planets are parts of the sun or came from...

Homework Statement How does the temperature of the Earth change when the sun suddenly stop radiating?:confused: how will the temperature vary with time? Please help me solve this one. can we answer this one using models or simply through theories? can you explain how? Homework Equations...

I might already know the answer to this but i just need to make sure. Does a suns mass reflect its volume? I ask because... The formation of a star simply put is: a planet gathers mass there-by gathering gravity there-by igniting and becoming a star…it becomes a star with x amount of mass...

I was trying to come up with a solution to the timeline when hypothetically speaking the sun would stop shining ( or emitting radiation). Now, gravitational issues aside (the sun as a body still there), how long would it take for median temperature to drop beyond freezing point around the globe...

Sun is an "ordinary" star I've read in different books the Sun is an "ordinary" star, and an "atypical" star. Anyone know which description is the correct one?

How do plants grow towards the sun? Thanks.

Homework Statement On October 15, 2001, a planet was discovered orbiting around the star HD68988. Its orbital distance was measured to be 10.5 million kilometers from the center of the star, and its orbital period was estimated at 6.3 days. Question A: What is the mass of HD68988? -- I...

Hello everyone, I've been on Electrical Engineering for a little while but new to this aspect of science. I'm not sure of course but when sunlight travels through space, would it be the approximate temperature of its' surrounding area, pretty cool? And when it hits our oxygenated atmosphere...

Homework Statement How long does it take the Sun to melt a block of ice at 0°C with an area of 1.10 m2 and thickness 1.07 cm? Assume that the Sun's rays make an angle of 31.1° with the normal to the area, and that the emissivity of ice is 0.0400. Homework Equations Q/t = IeAcos(theta)...

Why does the sun appear to have such low surface gravity? Most would say the the nuclear reactions inside the sun continually pushes matter outward against the force of gravity, but this does not account for the slow fall of solar flares and speed of solar wind. According to the current...

Hi. I'm really not sure if I'm posting this in the right place. If not, I'm sorry. Anyway, here's the thing: I'm doing research for a fantasy novel I'm writing. I know virtually nothing about any kind of science, so I need help with the following question: if the sun were to rise in the west and...

I'm going nuts trying to figure this out... in textbooks and online, everything i read says that the moon and Earth have a much stronger gravitational force between them than the sun and the earth, and this is why the moon has greater effect on tides than the sun. They all say that this is...

How much does the moons mass contribute to the Earth's orbital distance and characteristics around the sun. If the mass of moon and the Earth were not joined At the hip or say the moon magically disappeared :rolleyes: would the Earth's orbit around the sun still be within the habitable zone...

Could one design an effective sun block which passes the spectrum necessary for Vitamin D synthesis?

I'm building a solar powered project to light a room. From what I find on the internet, the average of sun light is given. It seems like to make my calculations I need to know what the minimum amount of sunlight could be. I haven't been able to find a website that shows the min and max sun light...

Hello everyone, I was wondering where I could get complete ecliptic longitude/latitude data over the course of as many years as possible of the Sun and Moon. Of course, by definition the ecliptic latitude of the Sun would be zero. The equatorial coordinates would be fine. Thank you for...

this just appeared in the peer-review journal Physical Review Letters. I noticed the preprint of it on arxiv last year and thought it was pretty far out. Here is the revised October 2006 preprint: http://arxiv.org/abs/astro-ph/0610844 Shining light through the Sun Malcolm Fairbairn, Timur...

Hi, Will a sun sensor work if the satellite is in the Earth's shadow? thanks!

Hi, Earth follws a straight path in 4-d space time.ok.now the Earth moves over the geodesic formed by the sun's gravity.now we also have other 7 planets.So does it mean that the sun forms different geodesic for differnt planets. if my question does make some logic than please explain me.

I recently did a school project about Copernicus, and after researching him, I have found that he believed the Sun was the center of the Universe, rather than the solar system. So, I was wondering: who was the person who discovered that the Sun was actually just the center of the Solar System -...

I have three questions. 1. Why are galaxies disk shaped and not spherical? 2. Theoretically speaking, if there were a hollow sphere at the exact center of the Earth and you were in it then what would you feel from a gravitational point of view? Would you hover and be able to bounce from...

Homework Statement The Earth's orbit around the sun is very nearly circular, with an average radius of 1.5x10^11 m. What is the average speed of the Earth in orbit around sun.Homework Equations d/t= 2pi/tThe Attempt at a Solution 2pi*1.5x10^11/ 31556926 it comes out to be 29865.95 answer is...