All Questions
Tagged with celestial-mechanics planets
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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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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?
