All Questions
121 questions with no upvoted or accepted answers
12
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2
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384
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What's the cause of this gap in this simulation of the Nice model?
A previous question brought me to this video (which has a spectacular change at about 0:34). It shows the orbits of Jupiter, Saturn, Uranus, Neptune, and what appear to be trans-Neptunian objects.
...
- 10.9k
6
votes
0
answers
115
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are alignment of star systems' orbital planes with ours better than random?
It obviously helps our observation of exoplanets if they transit their star from our point-of-view. I would guess that the chances of this alignment are better than if their orbital plane was randomly ...
- 161
4
votes
0
answers
37
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How did the radiative flux of each gas giant planet change with respect to time (since their formation)?
We know that each gas giant planet was warmest when it was young. This warmth came from internal heating from both radioactive decay and from gravitational potential energy. This warmth, in turn, ...
- 3,662
3
votes
0
answers
69
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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 ...
- 12.6k
3
votes
0
answers
163
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The causes of the nodal precession of a satellite in Earth orbit?
All artificial satellites in Earth orbit between the polar orbit and the equatorial orbit are subject to a nodal precession caused by the equatorial bulge of the Earth at the equator.
How the ...
3
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0
answers
112
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Can we rule out life swimming in the oceans of Europa and Enceladus on the basis of a lack of available energy?
Jupiter's moon Europa and Saturn's moon Enceladus (and several other moons too) have large subsurface oceans of liquid water, an ingredient considered essential for life. These two moons occasionally ...
- 141
3
votes
0
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91
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Barycenter correction for inner planets in solar system?
I want to run simulations of the solar system, and I've read in some papers that to speed up the simulations it is useful to use the barycenter correction of the inner planets (from Mercury to Mars), ...
- 43
3
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0
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106
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How can a gas giant be said to have an atmosphere?
They are made of gas, right? So, there won't be a solid-gas or liquid-gas boundary that defines where the atmosphere starts. So, if there isn't a boundary, we can't define part of it to be an ...
- 1,296
2
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0
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37
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Can the rotation of the liquid layer of the core around the solid core stop a planet's overall spin rotation?
In some planets like Earth or Jupiter there is an external liquid or molten layer of the core which rotates around a more deeper solid core (partly due to the planet's spin itself). This dynamo effect ...
- 2,878
2
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0
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57
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Would ocean tides on the moon of a gas giant really be kilometers high?
I was reading an article on exomoon habitability constrained by illumination and tidal heating. The article imagines an Earth-like exomoon around Jupiter-like host planet. That got me thinking about ...
- 21
2
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0
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64
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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 ...
- 221
2
votes
1
answer
101
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Are there any types of winds or waves that are produced just by Earth's rotation?
Are there any types of wind or waves caused/produced only and exclusively by Earth's rotation? Not influenced by Earth rotation, but produced solely by it?
In the case of waves, are Rossby waves 1 and ...
- 2,878
2
votes
2
answers
157
views
A simple proof that under Newtonian gravity rotating massive bodies are ellipsoids?
Here is my attempt at deriving the shape of an idealized rotating massive body under Newtonian gravity, assuming that the gravity force points towards the center of mass and shape of the body is ...
- 523
2
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0
answers
117
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Inner and outer orbital limit of planets in single-star systems
I am trying to find a rough cut-off of the inner and outer orbits of native planets around a single star. I know about the Roche limit and Hill Sphere, but these are not the limits I am looking for. I ...
- 31
2
votes
2
answers
256
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Tidal forces between Moon and Earth
I started studying about gravitation recently and I came across the fact that when finding the gravitational force between the earth and some point mass in space, we can consider the mass of the earth ...
- 177
2
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0
answers
81
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Theoretical lower limit to the density of a planet
If a celestial body is too dense, hydrogen fusion will ignite and it will become a star. As such, there is an upper limit on the density a planet can have.
But is there a lower bound on the density ...
- 467
2
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0
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55
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Could a planet experiencing tidal locking have a habitable area?
I wonder if it would be possible that, on a planet that always shows the same face towards the sun, there is a habitable area for some life-form similar to that of the Earth. I guess, since one face ...
- 590
2
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0
answers
360
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Heat transfer on Mars
SCENARIO:
I have been tasked with finding the heat transfer across a composite wall on Mars.
On the left of the wall there is air maintained at Earth atmospheric conditions and room temperature (101 ...
- 21
2
votes
0
answers
55
views
Long-term fate of hydrogen atoms in a rogue planet
Imagine a rogue planet drifting in intergalactic space. For the sake of specificity, suppose that it is the size of Jupiter and composed of pure hydrogen. What will happen to it over the next $10^{...
- 4,110
2
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0
answers
55
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Jupiter's formation
Two days ago i went to a mathematics conference where there was a paper presented on Jupiter's formation via disk-instability model.
I know that there are two different theories for the formation ...
- 155
2
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0
answers
166
views
What happens when a planet's core freezes?
We know the Earth's interior is differentially rotating -- the core is rotating much more quickly than the crust. This is possible because the outer core is liquid and is presumably low enough ...
- 121
2
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0
answers
130
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How strong can tidal forces get?
I am imagining a planet the size of Earth being in close proximity to something of high mass such as a gas giant or a star, but ultimately I'd be more interested in how to figure this out myself.
So (...
- 121
2
votes
0
answers
82
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Could there be a planet just as the Earth, but bigger?
Could there be a planet twice or thrice the size of Earth but while being the same? and by the same I mean, hosting the same life as Earth, having a day last 24 hours and a year 365 days.
Basically, ...
2
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0
answers
249
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Only gravitation and Newton's $2^{\mathrm{nd}}$ law needed to derive Kepler's laws?
It is known that Kepler's laws of planetary motion can be derived from Newton's laws of motion and his law of universal gravitation. However, are all of Newton's laws of motion necessary?
According ...
- 143
2
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0
answers
60
views
What speed should have an alone planet to have a habitable zone due to relic radiation?
What speed should have an alone planet to have a habitable zone due to relic radiation, without any star involvement?
How much time the planet will be able to remain in the habitable zone before the ...
- 11.3k
2
votes
0
answers
113
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Stable planetary rotation states
In reading an article about theories as to how the slow retrograde rotation of Venus may have come into being, the article Why Venus Spins the Wrong Way (Franzen, 2001) stated that
it is bound to ...
user29350
2
votes
0
answers
854
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For two planets in a 2:1 mean motion resonance , where will their periastron and apastron points be?
I want to animate the changing orbits of planets when they enter a mean motion resonance. Using a 2:1 resonance, I want to show a low-mass inner planet and a low-mass outer planet being tugged by a ...
- 21
2
votes
0
answers
862
views
How do I find equations for the distance of the planets relative to one another?
I know I should be able to piece together some basic Newtonian equations for this, but I'm not sure where to start. I want to be able to choose one planet as the center and calculate its distance ...
1
vote
0
answers
66
views
Why does a moon's orbit get more circular with time?
I understand that there is a transfer of energy between a moon and a planet depending on whether the moon is orbiting faster or slower than the spin rate of the planet. This would obviously change the ...
- 257
1
vote
1
answer
169
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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 ...
- 11
1
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0
answers
29
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
0
answers
30
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How to obtain exoplanets transmission spectra from JWST's NIRISS data of WASP96?
I was having a look at JWST's NIRISS data of WASP96 (specifically at the x1dints fits file which should be already calibrated). From this, I would like to obtain a result in a fashion similar to the ...
- 69
1
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0
answers
48
views
Does the Lagrange Point $L_3$ exist in practice in the multi-body solar system?
Lagrange Points ($L_1$ through $L_5$) in a restricted 3-body system are well documented. Traditionally body 1 (M1) is the central object with a mass much greater than the other two objects. M2 is ...
- 111
1
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1
answer
72
views
How do we find the centripetal forces of 3 planets revolving around a point given that they have the same mass?
Let's say we have three planets revolving around a point. We know that the force of gravity acting on all of these planets can be taken from $g = G{m_1m_2 \over r^2}$. We can derive the velocity of ...
1
vote
0
answers
34
views
How would water pool on a disc-shaped planet of Earth mass?
All this flat-earthism stuff is best ignored (although that is sometimes difficult) but it did get me wondering about the physics behind the pooling of water on a disc-shaped planet. Not for the sake ...
- 1,319
1
vote
2
answers
267
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Simplest expression for gravitational flattening of Earth-like planet, from zero rotation rate to Earth rate, to within 10 percent error
Richard Fitzpatrick discusses the rotational flattening of a celestial body. A model that assumes homogenous density arrives at a difference between the Earth's equatorial and polar radii of 27.5 ...
- 22.6k
1
vote
0
answers
42
views
Atmospheres and oceans on lower gravity planets
Using Earth as an example, how much less gravity could the planet exert and still retain its atmosphere and oceans? Or is it a matter of size, mass, magnetosphere, place in the solar system, all of ...
- 111
1
vote
2
answers
96
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How are the locations of solar system planets expressed in their orbits?
and where can I find the data about the locations of the solar system planets during their entire year?
I would like to find the data on the orbits of solar system plantes. Also I would like to know ...
1
vote
0
answers
79
views
Find minimum radius of an asteroid before it becomes round using bulk modulus and hydrostatic equilibrium
How big must an asteroid be before gravity makes it round and hydrostatic equilibrium comes into the equation? Let's say that being a round planet requires a radius error of $\frac{\delta R}{R}$ that ...
- 11
1
vote
2
answers
133
views
Is there a smooth transition from inverse quadratic gravity to linear gravity?
I can't remember exactly what it was, but I remember going through a problem in physics related to gravity on and inside a sphere, and found that inside, gravity acts linearly as a result of some ...
1
vote
0
answers
44
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When do planets formed via core accretion in a proto-planetary disk stop gaining mass?
I was just trying to go over some of the contents in my exo planets course and wanted to know that if all the planets that form via core accretion continue to attract all the dust in a proto-planetary ...
- 1,545
1
vote
1
answer
46
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Which planets of our solar system could be discovered from another solar system with present technology?
Recently many exoplanets have been found orbiting nearby stars. Assume there is a civilization with identical technology residing in a nearby (< 100 light years) solar system. Could they discover ...
- 1,251
1
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1
answer
55
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Between Mercury and Venus, which planet produces a longer transit? Assuming both planets describe same path on the solar disk
Is it even possible to give a definite answer to this question? There are a lot of factors involved in this like Earth's position and motion relative to the planets and of course their own motion and ...
- 11
1
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0
answers
20
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How does the NASA InSight lander determine the depth of a Marsquake?
With only one lander with this type of equipment at one location, how can the InSight lander's investigators be so sure of the depth of the Marsquakes it detects?
- 4,709
1
vote
0
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118
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Does frame-dragging affect planets?
The question has come up many times as to why the planets in our solar system lie in essentially the same plane. The most common answer is that they started out that way due to the accretion disk ...
- 15
1
vote
0
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163
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On a planet with winds faster than sound, what would it sound like?
I'm watching a Youtube video of the strangest planets and some of them have atmospheres/winds that constantly go at like 20x the speed of sound, ex: HD 189733-b .On earth, fast winds is actually ...
- 121
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0
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22
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How severe would the consequences be if the earth's moon were wrenched from orbit?
The old TV series Space 1999 from the early 1970s seems to have resurfaced on Youtube reminding me of something I watched as a child.
It is one of those obviously ridiculous SciFi series (from the ...
- 2,592
1
vote
0
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140
views
Gravity train and fastest path
As a fun exercise to kill some time, I have been thinking in the gravity train. For a point mass falling through a tunnel dug from pole to pole in an spherically symmetric planet of radius $R$, the ...
- 940
1
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0
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60
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Why does a starshade have to be put so far away from the telescope?
I understand why starshades have the shape they do, but i don't seem to understand why they have to be put so far away from the telescope. Why can't we keep the same apodization function, but just ...
- 141
1
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0
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48
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Which planets would be visible from the Saturn system using the Naked Eye?
I was wondering which planets would be visible using the Naked Eye from Saturn? Would these planets always be visible or disappear as they got further from Saturn? Plus which planets wouldn't visible ...
