Questions tagged [planets]
Celestial body that orbits following an elliptical path around a star or stellar remnant.
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Issue while understanding gravity/radius of earth graph [closed]
I have following question.
What are my opinions?
1. Option 1 - This is incorrect. I think dotted line in option 1 from bottom to peak represents center to surface of earth. After the peak, line ...
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How to measure the ratio of a planet's radius to a star?
I was reading a physics problem related to astronomy, and upon re-reading it, I realized that it could be really indicated to extrapolate some really interesting physics-related information.
One of ...
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Potential energy with different heights [duplicate]
If system consists of earth and ball and ball is dropped from height $h_i$ to $h_f$, then:
$\Delta U = -(W_{earth} + W_{ball})$ ($W_{ball}$ can be neglected since it's small)
$\Delta U = -(-mg(h_f - ...
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Dynamic equilibrium of planets
We can describe statical equilibrium ( forces, moments ) in a cuboid $$ \Sigma F_x=0,\Sigma F_y=0,\Sigma F_z=0~$$ In dynamics can we describe similar dynamic equilibrium within an inertial ...
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Can gravity of planets besides Sun and Moon affect tides on Earth?
The tides in some places on Earth are over 50 feet. If the gravity from Venus had a ten thousandth the affect of the Sun and Moon on a 50 foot tide it would make a difference of one twentieth of an ...
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What does Newton's Theorem XXXIII in his book "Principia" mean?
If to the several points of a given sphere there tend equal centripetal forces decreasing in a duplicate ratio of the distances from the points; I say, that a corpuscle placed within the sphere is ...
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How would the volume of a drop of water on the Moon and other bodies compare to one on Earth? (indoors of course!)
Searching for "volume of a drop of water from an eyedropper", I ran across this answer on Quora:
It depends on the size of the dispensing tip, but generally for a Pasteur pipette it is ...
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What is the gravity in the center of Earth?
Let's suppose the earth is perfect sphere and let's ignore its rotation and movement.
What would happen if i would be in the center of the earth? Would the gravity be zero in any direction so i wouldn'...
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Very Basic Question about Kepler's Second Law of Planetary Motion
In order to derive Kepler's $2$nd law, in the lectures we have used the conservation of angular momentum, where we defined the trajectory of a planet in a two dimensional plane (the plane where the ...
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If another planet was opposite Earth, would we be able to observe it?
Imagine another Earth-sized planet, in the exact same orbit as Earth, but 180 degrees out-of-phase. In this arrangement, at all times, you would be able to draw a single straight line through space ...
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Why do the planets tend to spin in the same direction as they orbit the center sun?
I mean, why do the spin angular momentum and the orbit angular momentum of a planet tend to have the same direction?
As we all know, a planetesimal $m$ orbiting a sun with mass $M_{sun}$ at $r$ will ...
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Will Hawking radiation violate baryon number conservation around gravitating bodies other than black holes?
Numberous articles discussing a recent research paper suggest that even stars and planets will eventually radiate away their mass like hawking radiation. My question is will this violate baryon ...
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Does a planet's "equatorial bulge" induce any kind of motions or currents in the atmosphere?
Rotating planets, like the Earth, are not perfect spheres but are instead oblates. This affects both the crust and the atmosphere, creating a bulge in the equator 1.
I was wondering if there are ...
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Does air in the atmosphere get friction as a planet rotates?
Does air in the atmosphere suffer friction in some way due solely to the planet's rotation? I mean, if you took a rotating planet with an atmosphere (not being influenced or heated by its star, its ...
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Do only gas planets have discs or even rocky planets may have them orbiting around?
Do only gas planets have discs or even rocky planets may have them orbiting around? If rocky planets are great in volume is then a higher chance for an orbiting disc to exist in the planetary orbit?
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Is it possible to determine if a planet can have a moon based on its mass and gravitational pull?
I'm curious, if based on what we know with Newton's law, can we determine if a random planet, knowing it's mass and gravitational pull, can hold a moon in it's orbit.
Or to phrase it another way, is ...
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Could rogue planets with cold nucleus have winds or water currents/waves due to the planet's rotation?
Are there any types of wind or waves caused and produced only and exclusively by a planet's rotation? Not influenced by the planet's rotation, but produced solely by it?
In the case of waves, are ...
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Does the Earth experience air resistance?
Consider the earth body excluding the atmosphere, undergoing circular motion around the sun. Does it experience air resistance due to the atmosphere?
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Why are distant planets illuminated like stars, but when approached closely (by a space telescope for example) it’s not illuminated? [closed]
when I look up into the night sky I see planets, not twinkling like the other stars, but still illuminated. However, when the Hubble or James Webb telescopes approach planets we see the local features ...
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What percentage of Mars' surface would be under the water if we dropped all of the water from moon Enceladus on it? [closed]
Enceladus, one of the Saturn's moons that is known for water geysers, is estimated to contain a body of water as big as a ball $220 ~\mathrm{km}$ in radius. That's about $\sim 4.46 \times 10^{7} ~\...
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How does Kepler's Second Law show that a planet further from the sun will move slower?
This is probably a very stupid question. We are told that due to Kepler's Second Law, which according to this very straightforward explanation:
"Kepler's second law of planetary motion describes ...
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If the Earth rotated slower about its axis, would your apparent weight increase or decrease?
The title above was a question on an exam that was marked wrong for me. I answered that if the Earth rotated slower (i.e. longer days), my apparent weight would increase. I based this on the ...
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On the tidal heating of a moon. What is the second Love number?
Years ago it was asked here how to calculate the tidal heating of a moon orbiting another body with a simple equation. The answer is very detailed. They explain the equation, its shortcomings, the ...
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Earth surface acceleration and inertial geodesics
I hope this is an appropriate question for this forum. It is one I have struggled with for a while.
I read that in GR gravity is not a force, and that the apparent force we feel and can measure (eg ...
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Is $F=mg$ derived from Newton's law of universal gravitation $F=Gm_1m_2/r^2$?
If so, that means gravity is only 9.8 m/s^2 at the surface of the earth?
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Gravitational field intensity
These are the two types of graphs between gravitational field strength $E$ and distance from the centre of the earth $r$. I found these two different graphs in two different books and I'm confused ...
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Change in $g$ effective due to rotation
$g$ effective at any latitude changes due to rotation of earth. Does it also change due to rotation when the body is at height or at depth or does it change only at the surface?
Edit: I am referring ...
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Correct explanation of tides [duplicate]
In the explanation of tides on earth there seem to be different versions for the second water bulge on the side opposite to the moon, while everybody seems to agree that the bulge on the moon side is ...
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Is Earth really flattened at the poles because of centrifugal force?
My question is pretty much all in the title. I was always told that our planet is flattened at its poles due to the centrifugal force generated by its own rotation. However I don’t see how centrifugal ...
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How does a gas giant planet hold it's spherical shape when it has tidally locked rotation in it's orbit around the Sun?
How does a gas giant planet hold its spherical shape when it has a tidally locked rotation in its orbit around its Sun? Wouldn't it fall apart without its gravitational pull from the rotation? How ...
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How the calculate the radiance of a planet?
In the last weeks I got interested in the topic of the irradiance of different planets in relation to their distance. Today I asked myself how could I calculate the radiance of a planet or moon if I ...
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Possible non-negligible physical effects that relate planetary/lunar geometry and seismic activity such as earthquakes?
Could any forces from the moon, the planets or the sun in orbit hypothetically influence seismic events on earth? And if yes how to approximately calculate and compare the magnitude of the forces?
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What are the Equations for Climate modeling of alien planet?
I am studying complex dynamic system and I would like to analyze the climating formation of a possible alien planet considering climate as a complex system .
For this I do not want to use a whole ...
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What would the nucleus of a water planet be like?
If we have a planet made out of water, would it be all solid? What about the nucleus? Would it depend on the size of the planet?
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Falling at the centre of the Earth
Let’s assume to drill a hole at Earth surface at the point P1. The hole passes throughout the centre of the Earth and finishes at the opposite side at the point P2. Let’s assume then that 1) Earth ...
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Solid surface of the gas giants [closed]
Given the gravities of gas giants and other similar celestial obejcts, I find it hard to believe that their centers aren't crushed to solid states.
If the gas giants and other similar objects have a ...
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Tholins color and scattering
One of the prevailing explanations for the reddish color of certain asteroids surfaces and planetary atmospheres, such as Jupiter's and Titan's, is the presence of complex polymeric molecules called ...
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Did Newton derive Titius-Bode Law of the planets in his Principia? [closed]
In college I was taught that no one knows why the planetary orbits conform to the Titius-Bode Law.
Recently I read that Newton HAD figured that out in his Principia.
Right Now I can’t even find a ...
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Why is mercury the closest planet to the Sun? [closed]
I just want a solid reasoning that why Mercury is the first planet away from the Sun, then Venus, then Earth, then Mars and so on.
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Calculating the excess radius of Earth in curved 3D space
This question is not a duplicate of Experimental measurement of the radial excess or How to derive exterior and/or interior Schwarzschild solution using Feynman excess radius equation?. The linked ...
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If the rock boundary exists, how did the planet Theia manage to collide with Earth? [closed]
Because it wasn't orbiting it, but in an errant orbit, but coinciding with that of the earth.
Much of its matter was absorbed by the Earth, and part was thrown into space, grouping together and ...
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High school thesis project about Jupiter's moon Europa [closed]
So basically, I have to write a thesis paper because I'm in the last year of high school. It is an independent research project and the culminating work of my studies in school, so it represents my ...
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Avarage velocity of a planet in a parabolic orbit
How the average velocity of a planet (over the entire time; $t = 0$ to $\infty$) orbiting a star in a parabolic orbit can be calculated?
If it's instantaneous velocity is $v$ (at distance '$r$' from ...
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How to calculate visible light part of black body spetrum?
So I was thinking about the formation of the Moon and currently the most accepted Giant Impact Hypothesis where the Moon formed as a result of a collision of proto-Earth and a Mars-sized protoplanet.
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Moist adiabatic lapse rate
Wikipedia gives the following equation to calculate the moist adiabatic lapse rate $\Gamma_w$, assuming that there is only one condensible gas (water vapour) mixed in the "dry air":
$\...
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Are moons always smaller than the planets they orbit?
I'm not a physicist, asking for knowledge. Is there any moon orbiting a planet, but bigger than that planet? If not, is it mathematically possible for a bigger object to orbit around a smaller object ...
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How can I calculate gravitational time dilation between two planets? [duplicate]
I am writing a school paper and chose to do it about gravitational time dilation. I wanted to calculate the time that passed on Mars when 1000 years on Earth went by. (probably a tiny difference). I ...
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Physics of a falling body within a spherically uniform system [duplicate]
I was reading The First Three Minutes and in the book it talked about how if a stone fell in a cave deep in the Earth we could calculate it's motion as if the surface of the Earth is the surface of ...
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Most stable shape if Newtonian gravity was proportional to $r^\alpha$
Consider lots of mass in isolated 3D space, close to each other. Consider that only the gravitational force (Newtonian) exists. Also consider that there is no rotational motion.
It is evident that a ...
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How can the cooling of Venus near the surface be explained during the time that the specific heat capacity of $\rm CO_2$ quadruples from 60 - 40⁰ C?
Imagine that a planet like Venus with an $\rm CO_2$ atmosphere of 92 bar near the surface could be cooled by shading it from the Sun.
The total heat content of the atmosphere with the initial 464⁰ C ...
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