# Tagged Questions

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### Is it possible to calculate Lagrangian isolines for local stars?

Is it possible to calculate Lagrangian isolines for local stars? SciFi descriptions of 'hyperspace' always talk about travel routes between the stars following some sort of route. As a thought ...
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### What is the “associated scalar equation” of equations of motion?

In an essay I am reading on celestial mechanics the equations of motion for a 2 body problem is given as: $$\mathbf{r}''=\nabla(\frac{\mu}{r})=-\frac{\mu \mathbf{r}}{r^3}$$ Fine. Then it says the ...
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### What does an $n$-body system with constant $T$ and $U$ look like?

Can someone give an example of a system where the kinetic $T$ and potential $U$ energy are constant (but not zero)? Here's what I have in mind: Say you have $n-1$ satellites of negligible mass ...
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### Square Cube Law?

I've heard about something called the square cube law. What is it? All I know of it is that it has something to do with mass of large objects and their gravitational influence.
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### What are Lagrange points in gravitation fields? [closed]

What are Lagrange points in gravitation fields? Additionally, what are their properties? For example, if a satellite or asteroid rested at a Lagrange-point.
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### Why do the planets orbit the Sun? [duplicate]

Why do the planets orbit the Sun? If it's because the gravity of Sun then why don't they just fall in and burn up?
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### Convert constant of gravitation to days and AUs

I'm working on a problem with celestial bodies and for my purpose days and AUs are more appropriate units than seconds and meters. So I tried to convert the constant of gravitation, $G$, like this: ...
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### Finding sphere of influence in multibody system

I would like to draw a boundary illustrating the sphere of influence of each body in a 3 body system. What is the best way to find such a boundary? My understanding is at the edge an SoI is the ...
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### Can a very small portion of an ellipse be a parabola?

We consider that when a body is projected from any height from the earth surface with a speed lesser than the orbital speed ( tangentially to the earth surface at that point.) it follows an elliptical ...
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### Is tripleaxis planet possible?

Imagine. Our solar system. Our sun. Then earth and moon orbiting it. And you have "powers" to create any planet you want, any size, any density, any weight and any velocity. Would it be possible for ...
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### Why turning velocity of star towards point “A” makes it's satelites, change their apoapsis to side opposite of velocity vector?

Why turning velocity of star towards point "A" makes it's satelites, change their apoapsis to side opposite of velocity vector? Sentence above turned a bit crazy or not understandable (possible ...
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### How to find a hyperbolic escape orbit with a starting point and a desired velocity after sphere exit

How would you find an escape orbit which includes a given starting point (not assuming a circular starting orbit) and escapes the sphere of influence of the current body with a given remaining ...
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### How to derive “Anti-Lagrangian” $L_4$ and $L_5$ points

In this paper on co-orbital dynamics the authors discover, numerically, "Anti-Lagrangian" solutions to the restricted 3 body problem. These Anti-Lagrange $L_4$ and $L_5$ points are 120 degrees ahead ...
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### Why do orbital speeds decrease further away from the focus?

Why do orbital speeds decrease further away from the focus? A simple question, but I want to make sure I am understanding this correctly: Is it ONLY a function of the gravity well? As in, the ...
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### Interpretation of a quantity from the reduced three body problem [closed]

Consider two bodies $S$ and $J$ that gravitate about their center of mass $O$, under the influence of mutual attraction. A third massless body $P$ is moving in the same plane. What is the ...
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### Potential Energy tends to infinity on the N-Body Problem

I need help to solve this problem related with the N-Body problem, i dont understand quite well what I need to define or to express in order to solve it. We assume a particular solution to the N-Body ...
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### What would it be like if we had a planet very close to us?

My desktop background rotates through a bunch of space and nature scenes, and this one came up. What would be the effect on people walking around down here, if another earth was looming overhead ...
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### What is the typical orbital life of an artificial satellite?

The orbit of satellites around Earth eventually decays, or so I read. This is typically caused either by atmospheric drag, or by tides. I would assume most satellites have a limited service life in ...
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### Gravity on the International Space Station

We created a table in my physics class which contained the strength of gravity on different planet and objects in space. At altitude 0(earth), the gravitational strength is 100%. On the moon at ...
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### Gravitation in a space that is topologically toroidal

In my scant spare time I'm building an Asteroids game. You know - a little ship equipped with a pea shooter and a bunch of asteroids floating around everywhere waiting to be to blown up. But, I wanted ...
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### On the origin of the rotation of celestial bodies [duplicate]

Possible Duplicate: Why does Venus rotate the opposite direction as other planets? Why does every thing spin? As far as I can imagine, almost each celestial body, star, planet, ...