All Questions
Tagged with celestial-mechanics planets
70
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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, ...
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2
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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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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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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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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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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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Why are the orbit of planets usually ellipses? [duplicate]
There has been a similar question about planets' orbits being ellipses but the answer circulates around how the circle is a special type of orbit which doesn't really answer my question.
Elaborate ...
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Angular momentum of a planet about apogee
Angular momentum of a planet about its apogee is maximum at __________
Now, I do know that
Angular momentum of a planet around the focus of the elliptical orbit (the sun) is conserved due to gravity ...
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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 ...
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Why is the shape of the orbit of the Earth as it is?
My View: I think that if the sun were only force acting on earth (as a centripetal force), the earth would have a circular orbit. Since other planets also exist , there also exists gravitational force ...
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Could a moon keep orbiting a planet forever?
Our Moon orbits the Earth further away each year due to the tidal forces but could there be a moon orbiting a planet where somehow keeps going further away by the tidal forces but its attracted again ...
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Help finding the eccentricity of an orbit
I am trying to find the eccentricity of a planet in order to be able to calculate perihelion and aphelion distances. I can get a lot of the equation, but am having issues with the angular momentum, ...
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How to represent orbital velocity of a planet on an elliptical path in terms of time?
Before reading this long message, please know that this is question is posted to know whether there is a method to find the relation between between the orbital velocity of a planet on an elliptical ...
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Does the formula $v = \sqrt{GM/r}$ work for elliptical planetary orbits?
Suppose we have a central mass $M$ and a smaller mass $m$ orbiting around the central mass in an ellipse:
The other point is the other focus. We know that elliptical orbits have the central mass in ...
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Simulating solar system with Newton's law
I made a simulation in C++ with Newtons law and test it comparing the planets positions with the position from Solar system Calculator Don Cross (which I converted from JavaScript to C++)
http://...
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Understanding the third Kepler law [closed]
Consider a system of two masse $M$ and $m$ with $m<<M$ and the mass $m$ orbiting around $M$. Then $m$ describes a elliptic orbit with period $P$ and the third Kepler law states that:
$$\frac{P^2}...
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What's the actual path of the planets?
I read about Kepler's Laws and in one of them he mentions that the path of a planet is an ellipse, with the sun as one of its foci (I'm narrowing down this to only our solar system).
However though I'...
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Orbit eccentricity and initial velocity
I was thinking about orbital velocities, and came across this question (Velocity of satellites greater than required velocity). Does the answer to this question imply that for planets going round the ...
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How do scientists calculate the orbital period of a planet?
It is known that you can calculate the distance to a planet using parallax, but how do scientists calculate the orbital period of a planet?
(Assuming they don't know the distance and can't use Kepler'...
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What determines if an object will stay in a planet's orbit? [duplicate]
Say you threw an object 10 AU from a planet at a certain speed, would this object stay orbiting around the planet or would it shoot off into space? And does it depend of the speed the object when it ...
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Lorenz System in reference to Astrophysics / Planetary orbits
From my research I have found that there are a system of ordinary differential equations for atmospheric convection.
What I am seeking are any Lorenz equations that apply to any areas of Astrophysics ...
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Validity of the two-body system approximation in astrophysics
I'm taking an intro course in astrophysics and studying Kepler's Laws of planetary motion - all of which are built over the assumption that we can approximate our system to one where there's only two ...
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How Can I Calculate the Speed Required for an Orbiting Planet to Pass Through a Given Point in Space?
I've been trying to derive an equation for this for a while now, but I haven't had much success.
Let us set up the equation. There is a star with mass $M$ and a planet that is distance $d$ from the ...
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Why are planet's maximal/minimal angular speed ratio harmonic?
See this Wikipedia page for Harmonices Mundi, a book by Kepler (yes, he was the one to discover the three Kepler's laws). The author writes:
He found that the difference between the maximum and ...
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Motions of planets from a non-rotating earth frame
Suppose you are hovering just above the earth at a fixed distance such that you are not rotating with it (the earth is obviously rotating about its own diametrical axis) but you are orbiting the sun ...
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Where does the radial velocity component come from?
Any object under the influence of a central force will have two components of velocities: Radial and rotational
I understand that the rotational velocity is there due to the centripetal force.
But ...
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Can dark matter explain the unusual orbit of transnettunian objects? [closed]
While we are struggling to find an hypothetical planet 9 to explain the unusual orbit of transnettunian objects, I was wondering if it could be just dark matter.
We know that the universe is mostly ...
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Is space-time fabric around Uranus tilted?
I am completely new in this field, so please pardon me if I am asking something which makes no sense at all :)
The Situation:
According to Einstein's theory of relativity, there is a 4th dimension ...
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Do all the planets in our solar system orbit the sun in the same direction and in the same plane?
Do all the planets in our solar system orbit the sun in the same direction and in the same plane? (as in a flat orbit if you are looking from "above")
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Ever looming shadow
If I'm not mistaken the reason the moon eclipses the sun is because the ratio of distance to size, in regards to the moon and sun, is 1:1. And is it not also true that the reason we only ever see one ...
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2
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Ptolemaic system parameters
I recently learned about the Ptolemaic system, which seems pretty accurate. There is even a simulator on the Internet: https://astro.unl.edu/naap/ssm/animations/ptolemaic.html
You can see that there ...
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Mars longitude reference?
Platforms like NASA's JPL HORIZONS web-interface for solar system dynamics often have obtainable parameters like sub-solar or sub-terrestrial longitude for a given time and celestial object. (example: ...
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Is there a maximum distance from a planet that a moon can orbit?
Given a planet that orbits a star, and a moon that orbits that planet, is it possible to define a maximum orbital radius of that moon, beyond which the moon would no longer orbit the planet, but the ...
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How come planets with different masses can orbit at the same velocity at the same altitudes?
Angular momentum is equal to r × p and angular momentum is also what gives planets with lower orbits a higher speed (because angular momentum is conserved). So as r decreases either m or v (p=mv) has ...
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How can I determine a planet's mass based only off of information about its orbit and its parent star?
I'm coding a video game with procedurally generated planetary systems and I want some and I want to make sure I'm at least somewhat scientifically correct. I've reached the part in my code where I ...
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Why does angular momentum being constant prove Kepler's first law?
So I was watching this video and this video on Kepler's first law in order to understand the proof of Kepler's first law. He started off by saying that for an ellipse, the distance from a focus point ...
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What is the second $r$ in this equation for the Two Body Problem?
$$r=\frac{r^2\frac{\mathrm d\theta^2}{\mathrm dt}}{\frac{Gm_2^3}{\left(m_1+m_2\right)^2}\left(1+e\cos\theta\right)}$$
I have this equation for the radial distance of a planet from the barycenter. But ...
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Can a planet have multiple significant sized moons?
The Earth has one moon at about 1/80 of Earth's mass. Is it possible to have two moons large enough each to subtend a >30 minute disk as viewed from the surface?
I have tried with various ...
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How do astronomers explain trajectories of planets?
I'm wondering how astronomers can explain the trajectories of planets because:
planets spin, so have angular kinetic energy. Thanks to the mass-energy relationship this means space-time curvature.
...
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Force on moon & what will happen next?
The moon is rotating around the earth. It is feeling a force by earth due to gravity. So if I some how manage to exert some force into moon, what is be the scenerio? I can think of:
The moon will go ...
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Speed at the perihelion [closed]
Hale Bopp has a period of 2400 days, with a mean distance from the sun at 174 AU and 1AU away in perihelion and 357 AU away in aphelion, what is its speed at the perihelion?
what formulas do you need ...
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Mercury's precession
I read in an article about Mercury's precession that Newton's law of gravitation predicts such precession of planets ;but fails to caluclate the precession of Mercury.But most of popular science ...
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Could a 'pulsar-like' planet exist due to the following properties?
A planet has been discovered with a composition believed to be made up of diamond. If such a planet were to host a massive satellite of high eccentricity, it seems possible that the large tidal forces ...
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How is the precession rate of planets calculated? For which planets do we know the precession rates?
From what I've read, precession rates of Earth, Mars and Moon are known. Why is that?
And how is it calculated?
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Shape of planetary orbits
What makes Venus' orbit almost circular, though mercury's is highly elliptical,even though it is closer to sun ? Further, Why is mercury's orbit most elliptical right after Pluto ?
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Is it possible to find the mass of a planet and its moon from only their diameter and the distance between them?
For example, a planet has a diameter of 200,000 km and its moon has a diameter of 20,000 km, the distance between them is 100,000 km. Would it be possible to find their masses?
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Would it be possible to pull Mars and Earth closer each other?
The burden of travelling between Mars and Earth comes from the distance. If the planets were closer, life could spread to Mars more easily, ensuring the survival of the intelligent lifeforms. What ...
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How deep does a gravity well need to be to remove particles from a planetary body?
I almost considered asking this question on WorldBuilding, however I wanted the brute mathematics on the subject, so please excuse the theoretical nature of this question.
I understand the basic ...
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Would a celestial body in a horseshoe orbit be tidally locked to the planet?
A smaller celestial body like a moon or an asteroid can be in a horseshoe orbit around a planet.
Since it might go inside the tidal lock radius (but does not stay inside it all the time), during the ...
