The sun Definition and 619 Threads

The Sun subtends an angle of about 0.5 degrees to us on the Earth, 150 million km away. What is the radius of the Sun? theta=l/R (2pi rad/360 degrees)0.5 degrees=2pi(150,000,000 km) This should be simple, but the answer I get seems to not sound right at all Have i set this up correctly?

Don't know how long they keep these linked, but it's a great shot! http://news.yahoo.com/photos/ss/photos_highlight_fp;_ylt=Atn756jNDFDUJDaq4wjpvw.s0NUE;_ylu=X3oDMTA2Y3J1dWFkBHNlYwNwaA--

We know, that photon change direction for 1.75'', when it flies close to the sun. This angle is proportional to radius of the sun. If we calculate clasically the angle is 0.82'' (arc second). Which is momentum, which is given to sun (or black hole) by the photon change of direction. Is the...

Does anyone else find this scary yet cool at the same time?:rolleyes:

How deeply into the Sun can we see? What are we actually seeing? Is wavelength related to how much we can see into the sun?

The Solar System is traveling around 155 miles a Second around the Milky way Galaxy. There are 31,556,926 seconds in a year. We will round off the Age of our sun from 4.76 Billion to 5 Billion Years for easier figuring. If we Multiply 31,556,926 seconds by 5 Billion Years we get...

Question says: Approximately how much energy would be required to ionize all the hydrogen in the Sun? How does this ionization energy compare with the thermal energy of the Sun? (Assume the uniform density approximation. The ionization energy of a single hydrogen atom is 2.18e−18 J.) Am...

http://www.acme.com/jef/singing_science/sun_shine-32.mp3

In about 5 billion years the sun will become a red giant. Would it be possible to stop with furtristic (super extrme) technology. Like by putting more hydorgen in the sun or somthing. It might be possible assuming that if were still alive that we could have the technology to that five...

Cornell's award-winning solar house to be auctioned April 7 By Susan S. Lang http://www.news.cornell.edu/stories/March06/solar.house.auction.ssl.html

If I am to understand correctly, light speed is the speed at which light travels through space. As I also am led to believe, our sun is some four lightyears away. I recall hearing that since it takes roughly four years for light to travel from the sun to us, the light we see during the day...

Nuclear Power Plants and the Sun I need some help again...:frown: 1. What are the fuel sources? 2. How is the fuel used to produce/release energy? 3. What are the similarities in the way they produce energy? 4. Are there any health hazards associated with the way they produce...

Now, the conventional way of viewing the solar system is that all the planets orbit the sun, but since you can declare anything at rest in space, can't you just as easily say that the sun is orbiting the earth, since it will appear that way if you hold the Earth at rest?

my evil teacher is making me and my friend to do a 12 page report. and the question is "how does the distance of a planet from the sun affect the temperature?" i would really apperciate it. thanks.

and does the sun also genrate the full EM spectrum? why does it do that and not a certain wavelength, is it possible to have certain ones, is that what dead stars do, like pulsars only emit radiowaves?

Does intensity of the sun affect this? I keep trying to do it, and when you have a square shape you should still see an image of the sun.. right? Well it is not working! I live in a place with VERY intense sun and no clouds... could this be the problem? Any help!? Thanks so much...

Why do total eclipses of the Sun by the Moon reach maximum eclipse about 40 seconds before the Sun and Moon's gravitational forces align? :bugeye:

I believe I have put together a pretty compelling case to demonstrate that the sun has a solid surface made of calcium ferrites that form structures and emit electrical arcs. This model is based on observations from the Sert program and SOHO, TRACE and YOHKOH satellite data. You can get the...

I believe that I have compiled compelling evidence from the TRACE, SOHO and YOHKOH satellite programs to suggest that the sun has a solid, electrically conductive surface that lies underneath the photosphere. You can find my website with lots of video and photographic evidence to support this...

is the sun moving simple harmonically up and down also?

My Professor posed a riddle in class today. He said "Question: Name two things that signify a trip around the sun". I not very good at riddles, but I know that Earth travels around the sun once a year. Thus the changing of seasons could be argued as signifiers (earth rotates on it's axis as...

The problem is this: Given sun of mass M and a body of mass m (M>>m) a distance r from the sun, find the time for the body to 'fall' into the sun (initially ignoring the radius of the sun). Our first equation is therefore \ddot{r} = \frac {GM}{r^2} . I am able to integrate this...

I am beyond lost with the question, so any help would be greatly appreciated. Consider a solid, rigid spherical shell with a thickness of 100 m and a density of 3900 kg/m^3. The sphere is centered around the sun so that its inner surface is at a distance of 1.5×1011 m from the center of the...

Orbits What does our galaxy orbit? more questions will follow once previous ones are answered

I have a question for you all. I asked my Physics teacher this in school not so long ago. I made an animation of it on a little art thing (which rocks btw, I suggest you all use it for your examples or theoreys) http://artpad.art.com/gallery/?idilmbnxbps In a nut shell: You're on a...

i have a feeling this was answered a while ago. however, my problem is, a shere of water (as it is in space) is launched into the sun from here, assuming it hits no graviational fields and continues on it's path into the sun, the following will happen: 1. the water, frozen from its trip...

Could it be that all the stars we see in the sky no longer exist?

We all know that stars, for example the sun, are made up of particles such as hydrogen, but a friend challenged me recenlty asking HOW we know this, and I was forced to admit that I didn't know the answer... so how do we know? probably a simple question, but my so-called "expertise" is more...

Can somebody explain how to calculate the sun's angle in the sky at a certain time of day? It is wanted to calculate the length of an object by it's shadow.

Was the sun ever a blue star in the early stages of its life? does this mean for a proportion of the time of the 5 initial billion years of the suns lifetime, the planets were cooking because of the suns initial powerful (blue) heat?

Hi everyone, I am fairly new to PF. So I start off with a rather strange idea, derived from SR. According to the first postulate of Special Relativity, it would be more accurate to say that the sun revolves around the earth, because we are stationary relevant to the earth, right? Correct...

Alright. Now, I understand that the Sun is 1/2 way through its complete H-He fusion cycle, and I realize that after this fusion cycle, it will pass through all the elements until Fe, (i don't know whether it passes through each element in 7 seconds, or it takes 7 seconds for each element). My...

I can't seem to obtain the right answer using the escape velocity formula. I think my problem is with the gravitational constant. I would like to find the escape velocity of the sun. v_e=\sqrt{\frac{2GM}{r}} or v_e=\sqrt{\frac{2\mu}{r}} v_e_\odot=617.54(km/s)...

Why isn't there a more pronounced effect from the Sun on tides? The distance from the Earth to the Sun seems negligible considering the mass of the Sun. While typing this out and thinking about it, the most reasonable explanation I can come up with is that the Sun has so much mass that the...

Why does a bight object like the sun have negative magnitude? TY

Could someone help me start this problem. My mind it in the angular momentum mode and I am having trouble seeing where to start on this one. :confused: The sun's radius is 6.96E8m and it rotates with a period of 25.3d. Estimate the new period of rotation of the sun if it collapses with no...

The Earth has an orbit of radius 148 million km around the sun. What is the speed of the Earth on this orbit? dont know how to do it i have used a couple of different formulas and haven't gotten it right can anyone help?

hey there, i am having trouble with what should be a really easy question! ********* calculate the mass of the sun assuming that the Earth's orbit is circular and with a radius of 1.5 * 10^8 km i got the period of the Earth's orbit around the sun in seconds: 60*60*24*365.25 then used...

What is the acceleration due to gravity of the sun at the distance of the Earth's orbit? i have no idea where to begin. Help

Ok, I keep trying to do the following problem: ----The asteroid Icarus orbits the Sun like the other planets. Its period is about 410 days. What is its mean distance from the Sun? (Hint: You can derive the mean distance with the paramters known for the Earth: Period of the Earth = 365 days...

The following site shows that when a sail is orientated so that it faces away from the sun, the net force is pushing outwards from the sun and is also opposing the orbit. http://solarsail.jpl.nasa.gov/introduction/how-sails-work.html It makes sense that the craft should slow down, but why...

I fear that I am way out of my depth here, being a mere mathematics student but anyway... We have been asked by our mathematical modelling lecturer to calculate the quantity of water required to extinguish the sun. I'm pretty sure that the exact physics and processes of the sun are not...

We're asked how long would it take for the sun to cool down if nuclear energy production suddenly came to a hault This is the question asked in one of my lecture courses given that the radius of the sun is ~ 10^9m, mass ~ 10^30 kg, luminosity ~ 10^26, and G = 6.7x10^-11 Am i correct in...

Dear reader, here is a neat problem, but kindof over the edge. when it is about the same distance from the Sun as is Jupiter, a spacecraft on a mission to the outer planets has a speed that is 1.5 times the speed of Jupiter in its orbit. Which of the following describes the orbit of the...

I know that when your skin is exposed to a lot of sunlight it turns darker in order to try to absorb some of the light's energy, which can help avoid burns, but why does your hair become blonde?

Through nuclear fusion the Sun slowly losses mass as it is converted to energy. The Sun also losses mass through coronal mass ejections. So after a large amount of time would this change in mass of the sun create a measurable change in the gravitational influence the Sun has on bodies in the...

Why is the spectrum of sunligt similar to that of a blackbody?

whats up guys. help me out NASA is giving serious consideration to the concept of solar sailing. A solar sailcraft uses a large, low-mass sail and the energy and momentum of sunlight for propulsion. The total power output of the sun is . How large a sail necessary to propel a 10,000-kg...

Currently the Earth has two extreme distances from the sun: Apogee and Perigee (one minimal, one maximal). Shouldn’t there be four extreme distances between the sun and the earth: pair of opposite minimums and pair of opposite maximums? Both the sun and the Earth have mass. So, there must be...

So I was playing around with Celestia and watching last year's transit of Mercury and this year's transit of Venus. They seemed pretty accurate to diagrams I've seen for ingress/egress locations. Then I got an idea. I flew to Mars and went looking for a transit of Earth, and to my surprise I...