The sun Definition and 634 Threads

In this video, around 2:28 He explains Earth maintain its same angular momentum even after sun disappears. I didn't get it. How Earth maintain its same angular momentum even after sun disappears?

I watched a documentary where it's said that light coming from the core of the sun takes thousend of years to reach the surface of the sun. Why is this so?

Suppose a sphere were to be placed around our Sun with a radius equal to the radius of the orbit of Earth, it would have a volume of 6.266x1022 m3. At any instant in time there would be 3.846x1027 Watts of energy within this volume in the form of photons from the Sun. Since...

How does GR predict the Earth's orbit around the sun? Newtonian mechanics predict a gravitational force that is a function of the two masses. Is the geodesic path of the Earth a function of both the sun's and Earth's curvature of space?

Since the Sun orbits the Solar Systems' Barycenter about once in every 12 Earth years, wouldn't it make sense to say the sun has a "year" - at least in a casual way? After all, although the sun has a lot more mass that the Earth, it orbits the Barycenter no less than the Earth does. We talk...

<Moderator's note: Yellow press link and headline deleted.> Scientists have theorized that a planet (or planets) may have collided with our sun in the solar systems past...

Homework Statement Assuming you know the core mass, and other data about the sun, such as temperatures and pressures. Find the density at the very center of a star. Homework Equations I think this may be involved. P(r) = p(r)/µmH kT(r) The Attempt at a Solution [/B] I don't know where to...

Sun is constantly producing energy from the particles inside it. It is not using the energy from out. So if this is true, as lots of energy is coming to the universe every day, isn't it dangerous as on day energy in the universe will be soo great to burst the universe as energy is entering but...

If we have 2 atomic clocks on Earth's orbit around the Sun, one on Earth's surface, at one pole, and the other on a spaceship, far from Earth, but traveling with the same speed around the Sun, the clocks would suffer the same kinematic time dilation or not? I'm asking this because the clock on...

I was interested in whether it would be possible to move the Earth away from the Sun by using two ion drives on the Moon. One Ion drive on the far side of the Moon would operate briefly while the Moon was exactly between the Sun and the Earth. The other ion drive on the side facing the...

Hi, I'm looking for some help please. I'm struggling to find an equation of the Earth orbiting around the sun. I don't need to include the mass of the sun and the gravity laws, etc. Just the equation to calculate a position in x and y. Can anybody help me please? My idea is to put the orbit...

Homework Statement The focal length of a concave mirror is f=20 cm. It is directed towards the sun and the sun makes an angle= 1° at the pole of the mirror. What is the size of the image of the sun? Homework Equations 1/u +1/v =1/f ...(i) ,magnification= v/u= l2/l1 where l1 =size of the sun,l2...

Moved into a house with some solar panels facing due south and some facing due west. Our latitude is 33.8 North in California. We are in the Mojave desert with very little cloud cover. The angle of the roof is 22 degrees from horizontal. What is the equation that will accept the azimuth and...

Black bodies are objects that don't reflect radiation. But If I shoot light beams to the sun, it doesn't reflect it , so does that mean the sun is a black body(or at least very close to a theoretical one)?

Blackbody radiation spectra of hot light sources ( stars in this case) should have the full visible light spectrum and still stars less massive than the Sun emit reddish light while stars more massive than the Sun emit blue light. How is the blackbody radiation spectrum altered by the star mass?

Homework Statement Homework Equations The Attempt at a Solution it looks like I got too big numbers for the uncertainty

Hi, there has been much media excitement about the launch of the Parker probe and some rather unhelpful attempts at dumbing down the language to the point where it no longer makes sense, or because science correspondence do not even understand the subject before they try to paraphrase PR...

The question “how do we know the composition of the sun” falls shorts everywhere I look. 1. There is the spectral absorption lines. Explanations given how that works, indicate how we know the elements, but fails to tell us how we know about the preponderance of Hydrogen and Helium...

If it takes anywhere between 5,000 to a couple of hundred thousand years (various internet sources have various values) for photons generated in the sun’s core to reach its surface and radiate out, what is the estimated mass equivalence of all these photons making their way out from the core to...

Homework Statement A new unit of length is chosen such that the speed of light in a vacuum is unity. What is the distance between the sun and the Earth in terms of the new unit, if light takes 8 mins and 20 sec to cover this distance? Homework Equations A new unit of length is chosen such...

I noticed HF radio waves travel farther and easier when the sun is out rather then during the night. Why?

Hi All, I would like to know if the following statement is true or false: The nuclear processes that happen inside the Sun can produce at least one unity of each of the known chemical elements. Best Regards, DaTario

When a cloud of gas reaches a critical density, thermonuclear reaction occurs and a star is born. all other gas is blown away by the staller wind. So how do we get stars so much more massive then the sun?

I had always thought that the Sun was about midway through its regular lifetime (i.e., before it becomes a red giant), but this article seems to say that instead of having another 5 Gy until then, it will be another 10 Gy. https://www.yahoo.com/news/scientists-sun-apos-death-even-164400014.html...

Red dwarf stars are main sequence stars but they have such low mass that they’re much ' cooler' than stars like our Sun. Then Simple question here : Sun is cool or hot??

Hi all, I have some difficulties understanding a formula for calculating the incidence angle for incoming solar radiation on a sloping surface. I found that: angle of incidence calculated as cos(j) = sin((pi/2)-surface slope)*sin(altitude angle) + cos((pi/2)-surface slope)*cos(altitude...

Greg Bernhardt submitted a new PF Insights post Either the Sun Is Getting Smaller or Gravity Is Getting Weaker Continue reading the Original PF Insights Post.

When the sun's rays break through a cloud there appears a radiating pattern but if one drew a line through these rays they would meet much closer than the distance to the sun. How come?

This question came up at another forum. The delta-v of potential guns is limited to the range 3 km/s to 11 km/s (hydrogen gun). Assume the astronaut is either on the moon or orbiting the moon. I'm wondering if a single impulse followed by gravity assists (and ideal planet alignment) could result...

Struggling a bit in my astronomy class. Trying to understand ..Is there a way to make a 90 degree angle between Earth, Mars, and the Sun? Mars would be the vertex. Is there a simple basic answer? TIA

Is the sun's magnetic field generated by a double dynamo? https://www.ras.org.uk/news-and-press/2680-irregular-heartbeat-of-the-sun-driven-by-double-dynamo Sorry if it was discussed yet but I couldn't find it.

The Earth is 1.50 × 1011 m from the sun. The earth’'s mass is 5.98 × 1024 kg, while the mass of the sun is 1.99 × 1030 kg. What is Earth's acceleration toward the sun? I'm really clueless how do this at all? I'm assuming it involves f=ma and GMm/r^2 formulas, but I really don't know. Help please...

How much smaller would the sun be if all it's hydrogen and helium turned to liquid? I can't figure out how to calculate this. But I thought it would be fun to visualize how much smaller in size a frozen sun would be compared to it's gas/plasma state. Anyone?

Homework Statement It's not a piece of homework, I'm doing a project and I've been wondering how I may be able to show it mathematically. I've covered the material before but it was a long long time ago... Homework EquationsThe Attempt at a Solution [/B] A-Thinking about modelling my "ship"...

Homework Statement 14.102 A comet at its closest approach is 125 x 106 km from the center of the sun (between the orbits of the Earth and Venus), where its speed is 45.5 km/s. (a) Show that the comet has an elliptical orbit around the sun. (b) Determine the period of the orbit in years (1 year...

So, I have heard that the deflection of starlight using Newtonian gravity is only half of the deflection predicted by Einstein. NE1 know where I can find an example of the former calculation? thanks

Hello everyone! I am a moderator over at the VS Battles Wiki, and I have some questions I believe one of y'all can answer. Basically the question is: how much energy does it take to destroy a star? We find this with GBE, but I have some questions as to calculating this value. As far as I am...

The discussion here https://www.physicsforums.com/threads/general-relativity-the-sun-revolves-around-the-earth.245334/ concludes that in general relativity there are no privileged reference frames so that, for example, it would be valid to use the Earth as a reference frame and say that...

Homework Statement Homework EquationsThe Attempt at a Solution If P is the power radiated by sun and R is the radius of the planet then power per unit area at a distance d will be P/4πd2 . I am not sure about how to calculate the power received by the planet .Do I need to multiply the above...

Homework Statement (a) What is the escape speed from the sun for an object in the Earth's orbit (of orbital radius R) but far from the Earth? (b) If an object already has a speed equal to the Earth's orbital speed, what additional speed must it be given to escape as in (a)? (c) Suppose an...

Hello, Orbital mechanics is a bit of mystery to me. Let us have a particle with mass m orbiting the Sun (with mass M)in a circular orbit with radius R. The velocity vector V is always tangential to the orbit. Let us also have a weak, constant ("drag") force Fd that is always pointing in the...

I'm confused by these pictures. I understand that the picture on the right has had color "assigned" to it because we can see uv light but the picture on the left is supposed to be taken in the visible spectrum. why is it yellow/orange and not white? isn't the sun white? both of these images...

The reason I made an account is to ask about the effect of gravity from an extra planet hiding behnd the sun. I think that if this was the case we would see much great impacts¿ say like the tides. Would they not be extremely high and low? Nonstop quakes that would be felt across the world? I...

Hello. 1. Homework Statement I have to find formula for effective cross-section (σ) of catching a comet with the Sun. I know mass of the Sun (M), radious of the Sun (R) and initial velocity (v) of the comet (at a big distance from the Sun). Homework Equations σ=πb^2, where b is on the...

Hello. 1. Homework Statement I have to find formula for effective cross-section (σ) of catching a comet with the Sun. I know mass of the Sun (M), radious of the Sun (R) and initial velocity (v) of the comet (at a big distance from the Sun). Homework Equations σ=πb^2, where b is on the...

How much would time pass between watching the sun set from ground level and then watching it set again from the top of a sky scraper? I heard once that this could be done using one of the towers of the World Trade Center. So I assume one could also do this using the Sears / Willis Tower in...

Sometimes it looks like there is a message here. Sun on 9/8/2017 - wavelengths 211, 193, 171 from http://sdowww.lmsal.com/suntoday/index.html?suntoday_date=2017-09-08 Beautiful!

Saving Earth - for a while: Could we shade the Earth from the Sun at a rate that keeps up with the Sun’s increase in Luminosity? There is a theoretical Dyson’s Ring that could be built around the Sun that would be used to tap the energy of the Sun. Could we construct something like that to...

1. The problem statement, all variables, and given/known data Venus is sometimes described as either the “Morning Star” or the “Evening Star”, since it can only be seen near sunrise and sunset, very close to the Sun in the sky. Why does Venus always appear close to the Sun in the sky for an...

Hi all, According to the sunrise equation, the hour angle of the sun at sunset is: cos H = -tan(a)tan(d) where H = the hour angle, a = latitude and d = solar declination angle. This equation says that H at sunset = -H at sunrise. Now, I have a few questions concerning that: 1) I was...