The sun Definition and 634 Threads

AR2665 ... largest spot group for some time Canon 6D, 800mm, f11, 125th, ISO100 ( the 800mm is a 100-400mm L lens with a x2 teleconverter) With my eyesight going downhill, I have really been struggling of late to be able to get sharp manual focus Dave

If star start from a big ball of hidrogen and the all the neutron to make helium. Thx for help!

Homework Statement Consider the Earth's orbit around the sun orbit as circular. Suppose the sun slowly loses mass from mass M1 to mass M2. Suppose that the initial orbit is R1 and the final orbit is R2. Express R2 in terms of the other parameters. 2. The attempt at a solution The problem I'm...

Hi all, which sun has highest concentration of UVB, but least concentration of UVA (skin cancer culprit). Right now, I'm in equator area (Singapore) with only 2 seasons (just in case if geography has any effect local sun's UV ray distribution). I've heard a lot of people saying that morning sun...

according to professor Einstein's theory space and time are one entity and can be defined as space-time. it states that that the faster we move in the space, slower the time passes for us. so if we are traveling of speed of light, we won't move in time at all. so how is that light from the sun...

so, I was told that only Up and Down are stable Quarks in the nucleus, and the others are only explained by observations in particular decay.

What is the reason for this? Is it because of the Earth's rotation?

Eventually the Sun will go through its phases and cool down. Is it possible to calculate how long it will take for the surface to cool to 75 degrees Fahrenheit?

A big part of water on Earth come from comets at the very early ages of Earth so I suppose that the comets has same age as the Earth. The Earth and other objects come from a waste after creation of the Sun. The Sun come from cloud of hydrogen and helium mostly. It is star of 3rd-generation so I...

This has always been something that has interested me. 2 things that I have found from the internet is that 1.) The Sun viewed from Pluto is (150 or 250) times brighter than the full moon. It varies of course depending on where Pluto is in its orbit. 2.) The Sun is about 30 arcminutes viewed...

This question arose in the context of another thread. https://www.physicsforums.com/threads/q-re-article-constraints-on-dark-matter-in-the-solar-system.900573/#post-5669854 Wikipedia gives an estimated value for the DM density near the sun of 0.35 × GeV/cm3 = 6.2 ×10−25 g/cm3. The value of the...

Homework Statement My homework involves calculating the amount of energy the Earth receives from the Sun in a given year. I actually have the answer, but what I'm confused with is that the calculation says that the Sun "sees the cross section of the Earth, a circle". So in the calculation, we...

I'm in the 11th hour of studying, and have run into a problem I can't seem to tackle from an old exam. I may be making some foolish mistakes, as I've now been staring at this thing for entirely too long. 1. Homework Statement (a) Calculate the force due to radiation pressure experienced by an...

If the sun suddenly disappeared, we wouldn't know it for about eight minutes because that's how long it would take the light to travel the distance between the sun and the earth. But I've often wondered; if the sun suddenly disappeared, would the Earth continue in its orbital path around the...

Homework Statement At lunch, the Sun's thermal energy incident on the surface of the Earth is 1.4 kW/m^2. Given the radius of the Sun, R, distance from Earth, r, and treating the Sun like a perfect black body, calculate the total intensity of its radiation and determine its temperature...

Dear Forum, I am filmmaker from Berlin and despite physics focus back in high school I am really bad at it. I am trying to get my head around some ideas I am working on and would kindly ask you for some tiny calculations. I hope this is OK and maybe even fun for someone here? So my questions...

Homework Statement I know the moon does. I know it is because tidal forces fall off as 1/r3. But why? Mathematically, I mean. Homework Equations F = GMm/r2 The Attempt at a Solution None

Homework Statement Find the force exerted on a particle on the Earth by the sun. Homework Equations F = - GMm/r2 r = distance between sun and particle M = mass of sun G = Gravitational constant m = ? The Attempt at a Solution Should I be using the other mass as that of the earth, or that of...

I was watching a show on one of the science channels a couple of nights ago and I think I heard that Jupiter's gravitational pull on the sun is around half a million miles (or could have been kilometers). Now, depending on Jupiter's position in relationship to Earths, at any time does it...

Hi! I guess this question must be easy, but it's driving me crazy: in what time of the year does the Earth "trails" the Sun in its current galactic movement towards Vega? And, could you please confirm that during this period Vega is not visible because it's always facing the "day side" of the...

Hello Forum There are three different mechanisms to transfer thermal energy: conduction, convection and radiation. It is well known that when two objects having different temperatures T1 and T2 are in contact, they will eventually reach a common intermediate temperature (the weighted average...

Hi all, I want to understand how retinal irradiance (Watts per square centimeters) from the sun is calculated. Some sources calculate 11W/cm^2 like this one...

I am trying to create a model/simulation for a pair of binary asteroids in orbit around the sun and I'm wondering what would the best way to do this? The restricted 3-body problem doesn't work as I can't assume any of the 3 bodies as having negligible effect right? However the full 3 body...

Homework Statement The sun is a pretty typical star with a mass of 1.99x1030kg and a radius of 6.69x108 m. Since it isn't solid, it doesn't rotate uniformly, but has an average rotation rate of 1rev/25d. A star with a mass about about three times that of the Sun eventually explodes as a...

why Earth moves around sun forever and ever and ever. My attempt for answer: Earth wants to move in straight Line forever and ever and ever(as there is no ext. Force)but due to massive sun space get bends(according to GR) and moving Earth starts moves in circle(or not perfect circle) , as it...

I have been wondering about space time and how it works like satillites putting corrections in there clocks by a few nano seconds a day because of gravity or lack of it! But I have also wondered about the effects of being super close to the sun and time that we observe there looking back at...

I read the Jupiter is so big that it doesn't really orbit the sun. Is that true?

The sun we see has a measured surface temperature of 5800K. This is the temperature of the photosphere , a glowing layer of plasma radiating energy from the sun. But when there is a hole in this layer and we look deeper into the interior the temperature drops to 3800K. How can this possibly be...

Earth moves around the sun in an elliptical path. When it comes close to the sun it speeds up. When it goes far, it slows down. This is acceleration and deacceleration. Why don't we feel both of these? I have read about it but haven't got satisfactory explanation.

So this is kind of a crazy hypothetical, but what would happen if you surrounded the sun in an invulnerable, perfectly insulating sphere that prevents anything from leaving. I imagine that as the sun heats up, the rate of fusion increases and the life time of the sun decreases. But that's about...

I have read popular accounts about the future predictions (the far future--a billion or so years from now) for our sun, and they say that as the sun ages, it will begin to expand and get hotter, eventually making Earth too hot for life. Is there a simple explanation for why the sun, after being...

I live about 1/4 mile from the Interstate Highway. I am far enough away the traffic can not be heard until the sun is very low on the horizon. Every even for about 1 hour when the sun is very low it sounds like the interstate traffic is in my back yard. It is so loud it is just like standing...

Homework Statement A spacecraft is protected from the Sun’s radiation by a planar baffle whose size is much greater than that of the spacecraft itself. The baffle is aligned perpendicular to the direction of the Sun. Show that the equilibrium temperature of the baffle is...

I understand the difference between comets, asteroids, and meteoroids. I was just reading about asteroids recently, and it occurred to me that when I read anything about these three types of objects the implicit (and sometime explicit) assumption is that they only apply to things that orbit the...

Scientists have measured both the blackbody spectrum and also the atomic spectra of various elements in the Sun. How do they distinguish between the two and filter out the light from either one?

So I have heard that the Earth is spinning away from the sun at a slow rate. Is this rate fast enough to negate global warming by a significant amount, or is it too insignificant to effect anything?

What would happen if the Sun collided with an exact copy of itself? I can't find any information online about this exact scenario. So what would happen to the Sun? What would happen to the Earth and the rest of the planets? Any information or help would be greatly appreciated. Thanks so much!

As far as I know, the Earth orbits around the Sun because of the centripetal force , and as far as I know, friction and gravitation from other planets should affect the circular motion of the Earth and so the path of the Earth should not be necessary that perfect. In addition, there must be...

I was thinking about adding another page to my website concerning the nearest stars, the brightest stars, etc. In a list of the nearest stars, the vast majority are brighter than the Sun. (I looked for stars with an absolute magnitude that was greater than the Sun's (4.85) and had a visual...

why was Earth considered to revolve around the sun and nt the other way round? why is it wrong to analyze planetary motion from Earth frame?

Homework Statement What fraction of its "year" (i.e. the period of its orbit) does a planet spend traversing the half of its orbit closest to the sun? Give the answer in terms of the eccentricity ε of the planet's orbit. This is problem 15 from page 852 of Adam's Calculus 3ed. No detailed...

Homework Statement Hi, I know that this probably is easy to calculate, but I have the ability to thing the opposite about problems, therefore I'm stuck with this one. The question is Determine the number of times the magnetic field has wound around the Sun by a heliocentric distance of 70...

Hydrogen fusion as described by proton-proton chain reaction that dominates in the sun produces two positrons for each helium nucleus produced. These annihilate with free electrons while the number of protons remain the same. Over time the sun is supposed to become positively charged, yet the...

Homework Statement Hey! I have trouble with an exercise that I need help with. Here it is: The magnetic field lines for the average interplanetary magnetic field (IMF) follow Archimedean spirals. i) Find the heliocentric distance r in Astronomical Units (AU), where a field line has wrapped...

Homework Statement THe sun has a mass of 1.99x10*30 kg. Jupiter has a mass of 1.90x10*27 kg and a mean radius of orbit around the sun of 7.78x10*8 km what is the speed that Jupiter travels in its orbit around the sun? Homework Equations fg=(Gm1m2)/d*2 fc=(4pie*2mr)/T*2 The Attempt at a...

Does an object falling into the sun reach approximately the speed of light?

I've written a java program to model the solar system. All my planets move in very well defined, stable orbits. The sun, on the other hand, is doing some very weird stuff. I've attached a plot of its path, a very zoomed in and a very zoomed out one. It isn't spiralling gradually inwards or...

As I understand it a coordinate origin is just chosen for convenience. So how can we state the Earth revolves around the sun when you could make coordinate origin at any point in the universe??

1. Compute the Larmor radius for a typical electron in the K corona.2. , , m=9.11×10-31 kg, q=1.602×10-19 CThe Attempt at a Solution My problem is I don't know where to find the other two values that correspond specifically to the the K corona. Then it becomes a simple plug-and-chug problem...

Homework Statement An asteroid is knocked out of the Kuiper belt and starts to fall toward the sun. (Assume it's initial potential energy and kinetic energy is 0.) a. Write down the differential equation for r(t) giving the position of the asteroid as a function of time. b. Solve the...