Sun Definition and 1000 Threads

  1. B

    Good wallpaper pics of our red sun from earth

    Hi Folks, Does anyone have a good source of space pictures in particular pictures of our sun in a few billion years viewed from earth? I tried google, not many good ones. Thanks
  2. N

    What is the relationship between pressure and depth in a scuba diver's lungs?

    Homework Statement If a scuba diver fills his lungs to full capasity of 5.5 L when 8.0 m below the surface, to what volume would his lungs expand if he quickly rose to the surface? Homework EquationsP=pg(H) The Attempt at a SolutionHeyguys! :) I know that P=pgh but I have volume...
  3. S

    What causes deviations between Sun and blackbody?

    Hello all, Does anybody have an idea why the solar spectrum, as measured above the Earth's atmosphere, has such bad agreement with the blackbody curve? I would think that any deviations such as sunspots would be averaged out because of the distance, and that in general (if any deviation)...
  4. P

    Physics of a satellite orbiting the sun

    One of the proposals for harnessing solar energy is to put solar panels in space. Either orbiting the Earth, or stationed on the moon, light waves could be converted into microwaves that pass through the atmosphere without losing any energy, then on to electricity on the ground. What I'm...
  5. L

    Observations versus Model-Based Statements about the Sun

    A solar model is used to calculate the expected temperature and density at all depths within the Sun. These results are then used to calculate the expected fusion rate within the Sun. We have confidence that the model is correct because it agrees with the observed characteristics of the Sun...
  6. W

    Angular Momentum and Angular kinetic energy about the center of the sun.

    Homework Statement The Earth is approximately 1.5x10^8 km from the sun. what is the Earth's angular momentum about the center of the sun. Note the mass of the Earth is 5.97x10^24. Homework Equations The Attempt at a Solution I got the answer, but my question is, when finding the...
  7. L

    Is our sun part of a star cluster?

    Because I was curious about this, I read here that, "Our own Sun is part of an open cluster than includes other nearby stars such as Alpha Centauri and Barnard's star." However, I cannot find any other pages claiming this, and the wikipedia entry on star clusters does not mention us being...
  8. C

    Volume of nebula needed to form a star with same number of atoms as sun

    1. Question: In one region of a nebula the mean separation of atoms is 2.3x10^-3 m. What volume of the nebula contains enough atoms to make a star, similar to the sun, of radius 7.0x10^8 m within which the mean distance between atoms is 1.0x10^-10m? 2. Volume of sphere 4/3(pi(r^3 ))...
  9. F

    Is All Religion Rooted in Sun Worship?

    This is a pretty compelling short documentary about how all major religion is based on ancient astrology and sun worship. There are many points in this video that cannot be argued with or debunked. Pt 1. Pt 2. Pt 3. What do you think?
  10. O

    Earth and Sun - Gravity problem

    Homework Statement Earth is a satellite of the sun with an orbit radius of approximately 1.5 x 10^11 m. a) What is the Sun's mass? **Answer:** 2.0 x 10^30 kg b) If the Sun's radius is 6.96 x 10^8 m, how does the Sun's density compare with Earth's density? **Answer:** Psun = 1/4 Pearth...
  11. Pattonias

    If ever there was a reason to destroy the sun

    I found this hilarious. This guy makes a pretty amusing argument for why we should destroy the Sun. http://destroythesun.com/" Surely, we should set aside our differences, band together and fight this threat.
  12. L

    Space Probe vs the Sun - Relativistic Frames of Reference

    I've had a good search through the archives and haven't found an answer to this question. Many apologies if this is old ground. . . Having read the threads on the Pioneer Anomaly a quick question to which I'm sure there is very simple answer (I just don't know what it is !): When...
  13. A

    How Can Spherical Trigonometry Help Calculate the Sun's Path?

    Last semester in my astronomy class, we tried to find an equation that would fit the path of the sun based on measurements we took, but we realized that due to the change in the tilt of the earth, it wouldn't be a simple sine or cosine graph, and we dropped the subject. I was wondering if there...
  14. A

    Hydrostatic equilibrium violated in the sun

    Hi there Problem is: if hydrostatic equilibrium were violated by .01% so that 0.01% of the gravitational force were imbalanced by the pressure gradient, estimate how long it would take the sun to change its radius by 10%. My attempts at solving problem: My feeling is that the...
  15. L

    What Happens if a Scale Model of the Sun Weighs as Much as the Real Sun?

    I'm writing an article in a plastic modeling magazine talking about scale weight. Plastic models come in many scales, i.e. 1/72 or 1/48, etc., so my article talks about what weight a model would be if it was also scaled properly for weight. For instance, a 2000 lb car, at 1/72 scale, would...
  16. S

    Do We Experience a Centrifugal Force from Earth's Orbit Around the Sun?

    Gday all, I was just wondering if we would experience a (very small) centrifugal force due to the Earth's rotation around the sun or not. I don't think there would be because the Earth and everything on it is in a state of free fall around the sun, but I have been told there would be a...
  17. Eagle9

    What the Sun will do with long rod?

    Here we have got a very long rod (100 million km length or so) built/placed on the lunar surface (near equator) and directed towards the Sun (imagine that Moon is in synchronous rotation with Sun and therefore that point (where this rod is built) is always looking at the Sun). The distance...
  18. D

    When the sun becomes a black dwarf

    Will the gas planets become solid? Since they are no longer receiving heat from the Sun?
  19. S

    Searching Neutralino Decay in the Sun w/ Amanda

    Hi so I am doing a presenation, on the indirect search for the neutralino from the sun at amanda In short: neutralinos are graviationally captured and settle int he sun.. they decay to produce neutrinos.. we detect the neutrinos at the amanda detector through muon productionSo what I am...
  20. K

    Did the Sun Go Dark Last Night?

    I've been reading this evening that the Sun went Dark last night for just about a min. Is this true or are people just blowing smoke?
  21. T

    How Did Scientists Explain the Sun's Energy Before Nuclear Fusion?

    The history of our understanding of the sun is a very rich area. Ancients believed the sun was a god while we now know the sun is an enormous body of fusion. What I would like to discuss is how the scientists thought the sun worked after the development of the basics of thermodynamics but...
  22. S

    Plotting Planets Orbits around Sun using Schwarzchild Metric

    Hello, I'm currently studying general relatively and am trying to plot orbits of planets around the sun using the schwarzchild metric. I've worked out the geodesic equations, working with c=1 to simplify things, and written a MATLAB script to plot trajectories, but I'm struggling to work out...
  23. B

    How much is space bended at the surface of the sun

    How much is space bended at the surface of the sun, only due to gravity? And how can it be calculated ?
  24. L

    How Does Increasing Solar Luminosity Impact the Inner Planets?

    I am currently researching how the sun's steady increase in luminosity is affecting the four inner planets. It's a fascinating subject. I haven't done any of the calculations yet (mostly because I am not that advanced in math yet), but I was watching a show called, "The Universe." On this...
  25. Khan Wolf

    Earth's position relative to the Sun.

    Would someone please correct my train of thought on this? I understood that the Earth's position in the Solar System is related to the gravitational attraction between the Earth and the Sun. If this thought is correct, then when the Sun enters its Red Giant phase, the Earth should be pushed...
  26. Evo

    Making diesel with sun, water, CO2

    It will be interesting to see if anything comes out of this. Sounds too good to be true. Continued... http://news.yahoo.com/s/ap/20110227/ap_on_bi_ge/us_growing_fuel
  27. M

    Sun Local Hour Angle and Latitude

    Homework Statement if: H = Local Hour Angle Lat = Latitude. Dec = Sun Declination. cos(H) = -sin(a)-sin(Lat)*sin(Dec) / cos(Lat)*cos(Dec) I wand to get The value of Lat . The Attempt at a Solution I Tried to make it simple By : 1 - multiply both sides by the denominator 1-...
  28. A

    What Would Happen if Our Sun Became a Pulsar?

    If our sun was replaced by a pulsar, would our solar system be sucked into it because of the increased gravity? How long would it take? Would we burn up because of the increased heat? How long would it take? Does it still emit visable light or only x-rays etc..? Would the light on Earth be...
  29. T

    Troubleshooting a Simple Sun Tracking Device: Tips and Solutions

    Hi friends! I have recently started a small project where I had hoped to build a simple sun tracker. My initial plan involved 2 Photovoltaic cells mounted at either end of a panel which was attached to a shaft which was then attached to a small DC motor. Both cells were hooked to the motor...
  30. S

    Understanding the Rotation of Stars: Origins and Processes

    Does sun rotate around itself? Do all of stars rotate around themsilves? If so, what is the origion of this rotation?
  31. R

    Calculate the energy from the sun.

    For my engineering class, my professor asked us to estimate the total energy output of the sun. The only tools we are allowed to use (for now) are: 1) A thermometer 2) A graduated cylinder 3) A container of water 4) An umbrella We are only allowed to use information that we ask for, or...
  32. MikeGomez

    Is the sun a black hole for low frequency radiation?

    Consider a photon of a certain frequency emitted from a distance slightly greater than the event horizon of a black hole. It seems possible that if a certain low frequency photon is not able to escape (due to becoming infinitely red-shifted), then a photon of a higher frequency emitted from the...
  33. B

    Calculating Time Deviation Inside the Sun

    How much slower is time ticking inside the Sun, compared to the surface, and how can it be calculated?
  34. R

    Why does the Moon orbit the Earth rather than the Sun?

    I was just wondering why, if the gravitational force exerted on it by the Sun is greater than the one exerted on it by the Earth, the Moon stays in orbit around the Earth? Is it due to angular momentum or are there any other factors?
  35. A

    Find the Mass of Sun if given are T and d?

    Homework Statement Knowing that the Earth spins around the Sun for 365 days and the distance Earth->Sun is 1.5x10^11 m, what's the mass of the Sun? Homework Equations F=G Me x Ms/distance^2 where Me - Mass of Earth, and Ms - Mass of Sun In some literature, I noticed that for...
  36. FtlIsAwesome

    Extraterrestrial sky color based on atmospheric composition and sun color

    How can one determine the color of another planet's sky from its atmosphere composition and parent star color? Earth's atmosphere is blue for most of the day, then turns red at sunset. Mars is sort of the opposite: it has a red sky which turns to a bluish hue at sunset. Until someone tells me...
  37. M

    From what frame of reference does the Earth orbit the sun?

    I have been doing some study on the theory of relativity and it has got me thinking. We say that the Earth revolves around the Sun but from what reference frame? From the reference frame of Earch, we are stationery and the Sun simply spins. Why is any reference frame more accurate than another...
  38. S

    Force on Earth by the radiation pressure of Sun

    Homework Statement Estimate the force on Earth due to the pressure of the radiation on Earth by the Sun. (At Earth's orbit, the intensity of sunlight is 1.37 kW/m^2.)Homework Equations Radiation Pressure=I/c Pressure=F/A Using SA of earth=510,072,000 km2 The Attempt at a Solution So I have...
  39. R

    Thermonuclear fusion in the Sun

    Q. Our present theory of the sun and the mechanism of thermonuclear fusion inside it predicts that the following reactions occur in the sun. 1H + 1H --> 2H + antielectron + neutrino 1H + 1H --> 2H + antielectron + neutrino electron + antielectron --> photon + photon electron +...
  40. A

    Thermonuclear fusion in the Sun

    Homework Statement Our present theory of the sun and the mechanism of thermonuclear fusion inside it predicts that the following reactions occur in the sun. 1H + 1H --> 2H + antielectron + neutrino 1H + 1H --> 2H + antielectron + neutrino electron + antielectron --> photon + photon...
  41. M

    Calculating Earth's Distance from the Sun in One Year

    Homework Statement Assuming that the Earth describes in one year a circle, of 92500000 mile radius, whose center is the sun, how many miles does the Earth travel in a year? The Attempt at a Solution How does knowing the radius of the Earth help me with this problem? I don't need...
  42. N

    Does the Sun's composition of hydrogen make it prone to explosion?

    I've recreated one of the first experiments I did in Chemistry many times - Water electrolysis to split it into Hydrogen and Oxygen, and prove the existence of hydrogen with a burning splint that goes "pop" in the test tube. The Sun is a massive ball of hydrogen, that uses Nuclear fusion to turn...
  43. B

    What Is the Significance of the Frost Line in the Asteroid Belt?

    What is the effect and what is the significance of the frost line that is presently located in the middle of the asteroid Belt? What Coincidence is there pertaining to the separation between Gas Giants and terrestrial planets. I know that it is the point where ice was able to freeze during the...
  44. M

    What Are the Best Books to Learn About the Sun?

    Hy. I need to read about the sun. What do you recommed ? Also i found some bibliography here but couldn't find. http://solar-center.stanford.edu/magnetism/bibliography.html
  45. L

    Does the Earth get bigger from the sun?

    I ran into a theory that stated that the Earth is actually expanding due to added mass from the sun's energy. Is this true and if true by how much?
  46. N

    NASA NASA Photos: Global Eruption Rocks the Sun

    "Dec. 13, 2010: On August 1, 2010, an entire hemisphere of the sun erupted. Filaments of magnetism snapped and exploded, shock waves raced across the stellar surface, billion-ton clouds of hot gas billowed into space. Astronomers knew they had witnessed something big. It was so big, it may...
  47. C

    Speed of the Sun in the Milky Way Galaxy

    Homework Statement The Milk Way galaxy rotates about its center with a period of about 200 million yr. The Sun is 2 X 10^20 m from the center of the galaxy. How fast is the Sun moving with respect to the center of the galaxy?
  48. S

    Is Work Done by the Sun in a Circular Earth Orbit?

    Okay, this is not a homework question, but a conceptual question already answered in the book. Problem: Suppose the Earth's orbit around the sun is perfectly circular. What is the work done by the gravitational force of the sun on the Earth through a small displacement over a small time...
  49. R

    What is the relationship between proton energy and temperature in the Sun?

    Hi I'm trying to calculate the energy of a proton in the sun. I know the temperature so I thought to use the equation E=3/2kT but in my textbook it says that I should only use E=kT. I don't understand why this is because surely each proton has 3 degrees of freedom? Thanks
  50. V

    Why the Sun Doesn't Move: Debunking Common Misconceptions About Solar Motion

    It is often safely assumed that the sun and the orbits remain relatively stationary(let's not consider precession) and the motion of the sun around the barycenter (without which the sun would be pulled towards the planets) can be neglected, but the resultant force of gravity on the sun is always...
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