Questions tagged [planets]
Celestial body that orbits following an elliptical path around a star or stellar remnant.
922
questions
0
votes
0
answers
19
views
How to calculate equilibrium height of tidal bulge?
I am trying to model the shape of the tidal bulge caused by the moon.
I asked GPT for a formula and it gave me equilibrium tidal bulge height as
$$\frac{2 R_{earth} G M_{moon}}{3 r^3 \Delta g}$$
and ...
0
votes
4
answers
75
views
What is the real shape of Earth? [duplicate]
As it now widely dicussed and accepted that Earth is not a 'perfectly round sphere/ball but more a 'oblate spheroid' why then do NASA have 'photographs' of a ROUND Earth?
4
votes
2
answers
258
views
Exact analytical solution for the surface gravity of an oblate spheroid
I would like to know if an exact solution for the surface gravity force components of an oblate spheroid has been published and if not can anyone derive it here?
Assume an ideal rigid oblate sphere of ...
0
votes
0
answers
28
views
Highly rare, dangerous for human health and efficient sources of energy? [closed]
I'm building lore for a human community for the sci-fi mech rpg called Lancer, inspired by Armored Core, and the criminal communities and aesthetics of Bomb Rush Cyberfunk. The idea is to make up an ...
0
votes
0
answers
38
views
Why is Earth a sphere? [duplicate]
Physicists and Physics enthusiasts . I am new to this platform. And I wanted to post a question . Since I have nothing in my mind. I wanted to ask , Why is the earth a sphere and not other shape?
...
0
votes
1
answer
55
views
What is the hydrostatic shape of an ideal rotating planet? [duplicate]
It is a well-known fact that rotating planets have a flattened spheroidal shape. However, the NASA site says about Haumea:
The fast spin distorts Haumea's shape, making this dwarf planet look like a ...
0
votes
0
answers
35
views
Is either Geocentrism/Heliocentrism more "correct" than the other? [duplicate]
Yesterday there was a casual discussion of the findings of the scientist Galileo in my German class. It was mentioned that his breakthrough was that, he found a convincing explanation that earth ...
0
votes
0
answers
34
views
Why does a total solar eclipse happen every 18 Months?
What is the math involved in calculating how often a total solar eclipse happens. Can you predict it by just looking at the period of the moon around the earth and the period of the earth around the ...
1
vote
0
answers
25
views
Holsapple simple scaling law [closed]
Could someone explain Holsapple's simple scaling law?
Furthermore, is Holsapple simple scaling law able to be used on Earth in the context of dropping an object and measuring the impact crater size?
...
0
votes
1
answer
98
views
Estimate Saturn's mass [closed]
How can you estimate Saturn's mass using data from Cassini's final moments in September 2017 (apoapsis on September 12 at 1:27 a.m. EDT Saturn time at a distance of about $1.3*10^6$ km from Saturn, ...
0
votes
0
answers
43
views
Gravity formula inside a planetary core
I am trying to work through this problem so that I can understand how to convert from pressure values to radius values inside a planetary core in a code. The core has variable density depending on ...
1
vote
1
answer
109
views
Atmosphere of a hypothetical planet
A hypothetical planet is 2/3 the radius of earth but has 1g surface gravity. Given the planet has the same surface gravity as earth, the atmospheric pressure would be the same. This would also mean ...
3
votes
0
answers
56
views
Why is sunset in mars blue?
This is the Martian sunset, as captured by the Spirit rover of NASA. Notice the colors are inverted, i.e. the direct rays blue and diffused rays red, which is exactly the opposite of what you would ...
0
votes
1
answer
59
views
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 ...
2
votes
2
answers
234
views
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 ...
-2
votes
1
answer
65
views
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 - ...
0
votes
0
answers
57
views
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 ...
0
votes
1
answer
91
views
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 ...
2
votes
1
answer
1k
views
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 ...
8
votes
2
answers
775
views
How would the volume of a drop of water (from a dropper) 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 ...
5
votes
2
answers
151
views
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'...
1
vote
1
answer
49
views
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 ...
16
votes
6
answers
4k
views
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 ...
3
votes
3
answers
155
views
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 ...
4
votes
1
answer
91
views
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 ...
3
votes
1
answer
50
views
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 ...
0
votes
2
answers
95
views
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 ...
0
votes
1
answer
35
views
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?
0
votes
2
answers
43
views
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 ...
1
vote
1
answer
59
views
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 ...
6
votes
5
answers
3k
views
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?
2
votes
3
answers
576
views
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 ...
1
vote
0
answers
32
views
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} ~\...
0
votes
2
answers
226
views
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 ...
0
votes
3
answers
271
views
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 ...
2
votes
1
answer
60
views
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 ...
1
vote
1
answer
91
views
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 ...
2
votes
2
answers
272
views
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?
0
votes
0
answers
53
views
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 ...
0
votes
1
answer
80
views
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 ...
1
vote
2
answers
332
views
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 ...
14
votes
9
answers
7k
views
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 ...
-1
votes
1
answer
76
views
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 ...
6
votes
2
answers
2k
views
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?
...
1
vote
0
answers
23
views
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 ...
1
vote
1
answer
69
views
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?
1
vote
1
answer
69
views
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 ...
0
votes
1
answer
59
views
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 ...
3
votes
1
answer
42
views
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 ...
1
vote
0
answers
40
views
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 ...