Sun Definition and 1000 Threads

I understand that the sun is made of 91% hydrogen, 8.7% Helium, and 0.3% other stuff. I looked up the atomic spectrum for helium and hydrogen [within the visible portion] and they leave most of the spectrum blank, albeit few lines of colour here and there, yet the white light that reaches us has...

astronomy-particle density/interior temp of sun Homework Statement The goal is to estimate the interior temperature of the Sun from its mass and particle density. a)What is the average number density of particles within the Sun, given that the average mass per particle is about 10-24 gram...

We know that heat is transferred from the sun to the Earth via electromagnetic radiation, right? Since no other form of heat transfer can occur in a vacuum that must be the case. We also know (?) that electromagnetic radiation does not dissipate over distance (could be wrong here). If that is...

Homework Statement The Sun is presently about 20 pc out of the midplane of the disk, and moving away from the midplane at about 7.4 km s−1. Using these as the current position, z(tnow), and velocity, vz(tnow), what is the maximum height zmax (in pc) the Sun will reach before turning around...

Why does sun appear elliptical during sunset and sunrise? I have read that when the Sun (or Moon) is near the horizon, the rays from the lower edge are bent more than the rays from the upper edge. This produces a shortening of the vertical diameter, causing the Sun to...

Hello, My Question is: What is speed of moon relative to Earth without the gravitational pull of the sun and hence the isolated length of the lunar orbit? :wink: Thank you.

Lets say all the helium in the sun fused to make oxygen, if that and the hydrogen combined to make water, even though it doesn't work out perfectly, let's say it did, and the sun turned completely to water, would it freeze because of temperature cause it to freeze, or the pressure cause it to boil?

(imagining a perfect Earth without rotation around its own axis etc) In which way does it; and which way doesn't it?

u all might have heard of sun storms, the news abt which was recently flashed on approx all news channels.' I don't understand what's the reason bhind these storms...? How do their intensities vary over a time period? whats the time period after which sun usually have storms?

Hello! I moved this at the recommendation of another mamber (namely, Andre). I have a question regarding the position of the sun in the sky. Since it depends on where you are, I am thinking of the Northern hemisphere above the Tropic of Cancer. Say, Northern Europe, Canada, etc. As the sun...

I need to calculate the radial velocity of the sun. Every time I try using Newton's Laws of Gravitation, I end up getting a value of 0.733 m/s. Apparently the actual value is 220000 m/s. Mass of Sun = 1.99 x 10^30 kg (3sf) G = 6.67 x 10^-11 Nm^2kg^-2 r = distance of Sun from galactic centre...

Homework Statement Find the maximum (aphelion) distance from the Sun for extreme elliptical orbit. (Semi-Major axis = 26) Homework Equations Eccentricity = Distance between foci/Length of major axis Major Axis = 2 * Semi-Major Axis Major Axis = Perihelion + Aphelion The Attempt at a...

Hello! I have a question regarding the position of the sun in the sky. Since it depends on where you are, I am thinking of the Northern hemisphere above the Tropic of Cancer. Say, Northern Europe, Canada, etc. As the sun moves across the sky, at noon the sun is often referred to as being...

Homework Statement How fast must a plane fly at a latitude of 26.3° so that the sun stands still relative to the passengers? Homework Equations I have no idea how I can solve this question. I would like to draw a free-body diagram, but I don't know how to do that either. If I could...

Television shows about astronomy explain the formation of our solar system as a result of remnants of a supernova. Gravity pulled everything together to form our sun and planets. The explanation given for the sun to shine was that hydrogen atoms at the core were being fused together to create...

Each month a different zodiac constellation follows around the sun day and night. The constellation is in the house of the zodiac sign but the actual constellation is the zodiac before. Example: the constellation of date is Libra but the constellation that follows the sun around is...

If we lived around a blue colored sun, or one of any different color, how would we perceive our world? Neglecting the effects of humans evolving around our G2 sun, how would the color of the sky or anything else change if helios were not its current reddish tinge? As well as this, if we had...

Lets say for a place that is at a latitude of 55 degrees, how high above the horizon the sun would be on the vernal equinox, summer solstice and winter solstice. Any hints on how to figure this out would be helpful I Know Vernal Equinox-When the sun crosses the Celestial Equator moving...

Homework Statement What is the totaly power emitted by the sun over all wavelengths (frequencies) according to the (incorrect) classical Rayliegh-Jeans expression for ρt(v) Homework Equations ρt(v)dv=8piv^2kT/c^3 dv The Attempt at a Solution I'm not sure how to start this one...

Homework Statement A asteroid is approaching our solar system from a great distance (r->infinity) and is headed straight for the Sun. Because of the gravitational pull of the Sun the asteroid is constantly accelerating. Radius of Earth's Orbit around the Sun (R_{e}) 1.5*10^11 Venus is given...

Several years ago Tethered experiment demonstrated that current can be produced by a long wire moving in Earh orbit, due to Earth magnetism. Being Earth inside Sun magnetosphere, wouldn't it be possibile to accomplish same task in a long wire properly positioned on Earth surface? Possibly at...

When did humanity realize that the Sun is similar to the night-time stars? I can find no reference to this in Wikipedia or anywhere else. It seems that ancient man thought that the Sun was unique of it's kind (similar to how we perceived the Moon before Galileo observed Jupiter in his...

Greetings, I've stumbled upon some peculiar images of our sun that appear to have extremely large objects in orbit which don't appear to be planets. The images are from the following NASA database. Each image is taken every ~10 minutes...

I want to make an order-of-magnitude estimate of the Sun's present-day luminosity. For this, I want to use just the following two pieces of information in a simple idealised model of (the mechanism of energy production in a star): 1) the mass of a helium nucleus is about 1 percent less...

The Earth rotating on its equitorial axis spinning on its poles. The Sun has its orbit on the ecliptic 23 degrees away from the spin if the Earth. Is the time frame different at the Earth on the Ecliptic plane rather than the Equitorial?

why is the light from the sun a continuous spectrum in the visible range , and of course it emits other frequencies of light . But if the sun is made mostly of Hydrogen and helium , in the nuclear reactions and all the high temperatures in the sun , are we oscillating electrons and...

Homework Statement 1. (a) Given that the distances to the sun and the moon are approximately 150 million km and 400,000 km respectively. and that the radius of the moon is 1740 km , estimate the radius of the sun.[Hint:k=9*10^9 Nm^2/C^2, g=10ms^-2) ] (b) Ancient astronomers knew that the...

I always hear people saying "Ptolemy thought that the Sun moved around the Earth, but it is the other way around: the Earth moves around the Sun". I think that's wrong. I think that Copernicus's theory is not "truer" than Ptolemy's. It is just that Copernicus's theory is simpler! But both...

In classical general relativity it is known that angle of deflection is proportional to radius-1 from the center of the sun. If radius is large, this angle is very small, what happens already at the radius of the sun. But what happens to this photon, when we include quantum gravity (QG)? I know...

How much dark matter is in the Sun, and does it have any effect on any process in the Sun? What percent of the total mass and volume of the Sun is DM by weight, and by volume? Does the high density of the Sun impede movement of DM? Is there a lot of DM trapped by the Sun's gravitational...

Me and a friend have been wondering if it would be possible for a person to outrace the sun. more accurately, in a plane. One of us is argueing that we would need to outrace the Earth's rotational velocity, the other is argueing that we could calculate the velocity of the sun by assuming that...

i've read some article about sun exposure to help body produce vitamin D, but, just out of curiosity, which part of body that should be exposed? is only head and hand will be suffice?

This was shown in a textbook about the two body problem, and they compared it to the energy potential of two atoms, but the sun and comet don't experience charge so that 'when it gets too close the nuclei repel each other'. It mentioned something about centrifugal force, but I don't understand...

I've read that along with the moon, the sun also has an effect on our tides. I understand how the moon would have an effect on tides, but I don't quite get why the sun would. According to my physics book, when something is in orbit, it's really just in free fall around the thing it's...

Bear with me, I am not even sure if I know how to properly word the question. Few days ago there was summer solstice - that means Sun was visible all day north of arctic circle. My question is - when will the Sun set down at 71°11'? Now, Sun is not a point, so perhaps better question is -...

I have viewed other threads regarding this thought experiment but have not seen any that answer my question. "If" the sun disappeared, the Earth would just continue on in a straight line, I understand that. But what about our moon? Would it continue to orbit the Earth as the Earth traveled...

for ease of explanation, imagine that the barycenter of two planets is the center of a wheel and that the planets revolve around the edges of the tire. the center of the tire (barycenter) is in orbit around sun, as if the wheel is rolling around in its orbit. my question is, is this possible? of...

We did an experiment to find out how water is heated as a result of sunlight. We had a bowl of water which we heated with a copper plate on the water surface, through which we sent a sinusoidal current. We didn't use a lamp, because water doesn't absorb visible light very well and since our bowl...

I'm witnessing an argument elsewhere about whether a vacuum is a good insulator in space. Person 1 said this: Person 2 said this: I said this: what would really happen if the vacuum between us and the sun were replaced with steel?

I'm looking into putting a "roof" over my pool. I wish to ensure that the roof does not obstruct the sun. You heard me. I wish to build the opposite of a shade roof. The roof is intended to protect my pool from detritus falling from surrounding trees (no, cutting them down is not an...

I have only taken my high school Physics course so excuse me if I don't understand some things right away. I looked at the two stickies and neither seemed to explain my question. I have been trying to understand why the moon's orbit's apogee moves around Earth over a period of time. The...

Homework Statement how many photons does the sun generate to knock one electron across the bandgap in a PV panel? I am doing a college level night school course on Photovoltaics and I have to do a short presentation on photons and how they produce useable energy. I thought it would be...

Sounds a bit crazy. But you have an almost infinite energy supply on tap. Easy to get to as well.

G'day. i'm a 2nd year Aero engineer student from Australia. I've had this question on my mind for the past few days now and can't seem to find much material on it. i was just wondering how the lightest elements (hydrogen and some helium) managed to come together in the center of the solar...

This coursework question I am faced with is very specific and quite difficult to explain so I have attached the question. The writing on the side is not that important so don't try and make sense of it. The question asks to find the angular velocity of 2 planetary gears (which are connected...

Hello, I am trying to revise for my Solar System exam and going through a past paper i have a question relating to something that we don't seem to have covered: "By estimating the energy output of the Sun's corona (in watts), comment on whether can be treated as a blackbody radiator...

Why does the Moon keep the same face toward the Earth but the Earth not keep the same face toward the Sun?

I have a question about the gravitational model used to describe tides: Is it correct to simply add the tide potentials respectively due to Earth and sun as most people do? (see for instance a good example of this approach in Eq 9 of: http://arxiv.org/PS_cache/physics/pdf/0701/0701301v1.pdf)...

Homework Statement What types of energy does the sun produce? Homework Equations N/A The Attempt at a Solution I feel stupid..but I think it produces Light energy as well as Solar Energy? Does it produce Light Energy?

How much more of less would you weigh (same as force) at the surface of the sun than on earth?