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Questions tagged [orbital-mechanics]

The application of ballistics and celestial mechanics to the practical problems concerning the motion of rockets and other spacecraft.

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What exactly are the “ν6 secular Sun-Jupiter-Saturn” and the “1:4 Sun-Jupiter” resonances?

In the recent Acta Astronautica article The edge of space: Revisiting the Karman Line, Harvard-Smithsonian Center for Astrophysics astronomer, Space SE contributor and "inverse namesake" of asteroid (...
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What are Kepler's laws (as he wrote them)?

There are of course many, many sources that quote Kepler's laws of planetary motion. This is preventing me from finding out what I really want to know: which is - what are Kepler's laws as he wrote ...
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Do all orbiting objects have barycenters?

From the simple perspective of someone like myself, it appears that our sun is "fixed in place" (from the perspective of the solar system itself) and that everything else of lower mass orbits around ...
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Calculating obital velocity from radial velocity

I'm not really a physicist so I don't know if it's possible to get the real orbital velocity of a star from its radial velocity. I'm working on a paper for school and I want to get the mean velocity ...
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Can Two Stars of One Same Type Orbit Each Other?

This is a simple, textbook definition of a binary star orbit. One low-mass star orbits a higher-mass star in a narrow but definitive center. For example, the high-mass star would be our own sun--a G-...
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Calculate eccentricity from apside altitudes? [closed]

I need to calculate the eccentricity of a satellite orbit with only the apside altitudes (height above the surface of the Earth), 400 and 1500 km. However, I don't know the semi-major axis ($a$) or ...
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1:1 resonance of two planets around a star in close proximity - approximate perturbative mathematical treatments?

This question is primarily about the mathematics of orbital mechanics. The circular restricted 3 body problem (in 3 dimensions) assumes two massive bodies in circular orbits around their center of ...
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horseshoe orbits

I'm designing a moon system for a fictional setting, and recently came across the idea of horseshoe orbits. The gist of my question is how many objects can share a horseshoe orbital at a time? I ...
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Why does the Earth's orbital eccentricity oscillate with a period of about 100,000 years?

This answer says: Earth's orbital eccentricity varies over time from being nearly circular (low eccentricity of 0.0034) and mildly elliptical (high eccentricity of 0.058). It takes roughly 100,000 ...
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How can Earth-Sun Lagrange points L1 & L2 even be semi stable considering the moon?

I know that the Earth-Sun Lagrange L1, L2, and L3 points are not considered stable over longer periods, especially when compared to L4 and L5... But, with the moon orbiting the Earth in the general ...
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Can a solar system exist where the second planet rotates fast, and the third planet is tidally locked to their star?

Today I read about the Romulan home star system and it looks like it might be impossible for such a star system to exist. Memory Alpha describes Remus: Remus was tidally locked, with one ...
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Do other planets affect the Earth?

Let say Mercury, Venus, the Moon were all in alignment between the Earth and Sun. They are all closest to each other in respective elliptical orbit. On the other side of the Sun you have the rest of ...
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How much are Neptune's and Uranus' orbits perturbed by Pluto and other KBOs?

Reading another question, I came across the argument that inconsistencies in Neptune's and Uranus' orbits lead to the discovery of Pluto. This brief write-up mentions Percival Lowell and William H. ...
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How can tidal heating lower Io's orbit?

This answer to the question Is Io a magic energy machine? suggests that the energy from the internal heating of Io due to tidal "squishing" as it moves cyclically closer and farther from Jupiter in ...
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Is Io a magic energy machine?

Io gets its volcanic heat from being flexed by Jupiter's gravity, and this seems to go on forever. That sounds like a magic energy source, since Jovian gravity is perpetual and Io seems to remain in ...
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Does anybody know how to get Sun-Jupiter Lagrangian points L4 and L5 RA and Dec?

I wanted to point at the L4 and L5 of Sun-Jupiter to find Trojan asteroids but I don't know how to calculate the RA and Dec of these. Do you know of any software that does it for you or how to ...
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Maximum distance for earth eclipse

First of all sorry if this question was already asked, but I made a small search here and on google and I couldn't find any answer, so.. Here I am. I was reading NASA's webpage about the Webb ...
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Aaditya L1 mission ISRO

ISRO's next mission to the Sun is Aditya-L1, (also here), which will be placed at the Sun-Earth Lagrangian point L-1. Why it is not placed near L-4 or L-5, since these are stable equilibrium point ...
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snapshot of solar system

I am working on a little project where I want to simulate the solar system to teach myself working with python and OOP. I want to calculate the orbits "real", from tangential velocities and ...
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Orbit of Mercury

As observed from the earth, the sun appears to move in an approximate circular orbit. For the motion of another planet like mercury as observed from the earth, would this be true? If not, why? What ...
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Eventual outcome of tidal acceleration and deceleration

So, I know the Moon experiences tidal acceleration from the Earth. And, from what I've read, if not for the fact that the sun would boil away the oceans and engulf both of them first, about 50 billion ...
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Can one approximate the semi-major axis of an orbit as the average orbital distance for eccentric orbits?

Kepler's 3rd Law (regarding the relation between orbital period and the semi-major axis of an orbit) applies to all elliptical orbits. But as I understand it, the only reason it is safe to use the ...
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How do comets and other solar system bodies gain energy to exit the solar system?

I recently learnt that some comets like C/1980 E1 (Bowell) interacted with objects like gas giants in the solar system and gained enough energy to exit the solar system. But from Physics, I know that ...
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How much could Earth's orbit shift without causing an ecological catastrophe?

Seeing the news about A/2017 U1 made me wonder what would happen if a similar object, but with a mass close to Earth's, had a close call with Earth. Could it shift Earth's orbit enough to quickly and ...
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When the Moon formed and early on, did it orbit over the Earth's equator?

Or was it always at about 5.14 degrees inclination or has the inclination changed over time? See diagram. James K's answer to this question got me thinking about this, and I don't mean to call him ...
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If the moon's orbit decays- how would it effect the moon's phases? [closed]

If a planet passed near the moon and caused its orbit to decay down to earth- how long could it take and how would that effect the visible phases of the moon on earth?
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Moments of inertia of planets

The three principal moments of inertia of Earth and Moon are reported, for example, in T. J. Ahrens, Global Earth Physics - A handbook of Physical Constants. I have found reports of the moment of ...
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If you lived on the far side of the Moon, how could you infer the existence of Earth?

Suppose that you deposit an astronomer, armed with our current knowledge of orbital mechanics, on a dome on the far side of the Moon, so that the Earth is perpetually hidden from them. (And, of ...
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Why do certain moons have their rotational period equal to their orbital period?

Our moon and Saturn's moon, Titan, have this feature. Because of this we only observe one side (hemispere) of our moon. Why is this? What is the Newtonian or astrophysics that would explain this? ...
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Could Earth Sustain a Ring? [closed]

Unlike Saturn's moons our moon is relatively much larger in ratio to the size of the Earth. Earth's moon's orbit is also elliptical and is at a tilt to its equator because of this would a ring last ...
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If I had a horseshoe orbit of two moons…

Consider an Earth-like planet, with two moons. I guess the two moons would have to be smaller than our own, for the system to be stable. Is that stable? I did some research, and apparently Janus and ...
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Orbits using Newtons laws

I am making a small orbit simulator. I figured out Kepler's laws and know how to work with them to "update" an orbit based on time. So now I want to know how I can describe orbits with newton laws. ...
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How large are the effects of nongravitational forces on comet Halley?

The effects of outgassing on comet orbits can be noticeable. Yeomans, in Cometary orbit determination and nongravitational forces, 2004, wrote: As the astrometric datasets improve and lengthen and ...
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How to find Greenwich Mean Sideral Time?

I'm writing a program that converts position in the ECI (CIS, EPOCH JD2000.0) coordinate system to WGS 84 (CTS, ECEF) coordinates. To do so, I'm following what's described in this document and ...
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Is there a connection between Jupiter's orbital period and the Sun's solar cycles? [duplicate]

The cycle of solar maximums and solar minimums are each about 11 years, which is close to the orbital period of Jupiter. I thought it was a numerical coincidence, until google turned up some results ...
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How do tadpole, horseshoe co-orbital states arise and how are they stable?

A recent paper in Nature "Planetary science: Reckless orbiting in the Solar System" (Morais & Namouni, 2017) presents the following series of four co-orbital states: While I understand the ...
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Why are these objects moving at Vastly Different Speeds along the same orbit?

UPDATE: The on-line simulation seems to be working beautifully now! I'd recommend anyone to go back and take another look to enjoy both the mathematical beauty of orbital mechanics, and the aesthetics ...
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Problem about orbiting of a satelite

Problem: There is an satellite that orbits the Earth. Its orbit is circular and its orbital plane is perpendicular to Earth's Equatorial Plane. It orbits is such that a person who is on equator see ...
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What stabilizes rings or accretion disks?

We think, more or less, that our Moon was formed from an accretion disk caused by a Mars-sized impactor. Cool. Tidal forces can break apart a moon, causing rings. Ashes to ashes, dust to dust: the ...
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What effect does time dilation have on bodies orbiting close to Black Holes?

As far as my (somewhat basic) knowledge of astrophysics goes in general the closer to a star your orbit gets smaller (because you travel less distance) and faster (because you're deeper in the gravity ...
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Can a bullet be fired on the moon and sent it into orbit?

I know you need oxygen for the ignition, but presumably, if the bullet is impervious (or water-tight) and if there is a little air enclosed in the bullet case, wouldn't that be sufficient to fire it ? ...
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Are the Trappist-1 planets in stable orbits?

The Trappist-1 planets all orbit very close to each other. During NASA's press release, they mentioned that these planets are close enough to disturb each others orbits. Is this system stable over a ...
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What is $\phi '$ in orbital mechanics?

For the last week or so, I have been teaching myself orbital mechanics within the context of Braeunig's Rocket and Space Technology. I noticed a symbol, $\phi '$, and was wondering what context that ...
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What defines a stable orbit?

While looking for a way to prolong an orbit via moon power I was faced with the parameters of what would be a stable orbit by length of time an object stayed in orbit, What is the definition of a ...
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J2 perturbations and orbits

I am trying to solve a problem where I need to calculate a satellite's orbit, but first I would like to ask for some clarifications from someone here that might know this stuff. I need to design an ...
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On orbital mechanics of evaporating planets

A planet orbits around its sun on an elliptic orbit, and loses mass slowly due to evaporation. How will the parameters of the orbital ellipse change as a function of time? Could we do a generalisation ...
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Calculate eccentricity with altitude and semiminor axes

Following on from this question, I wish to know how to find the reverse - how to find eccentricity given a Semi-minor axis & altitude. I want to use something based on $$b=a\sqrt{1−e^2}$$ but ...
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Intercept a NEO trajectory

I need help with an exercise in the book that I can't tackle. I need to calculate how much time we have to intercept and eliminate a NEO. I got the following orbital parameters: a=-2791.44 km (semi-...
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Effects of the solar tide on planets

It’s well known that (lunar) tides on Earth result in a transfer of angular momentum from Earth proper to the Earth–Moon orbital motion. That’s why the Moon resides now in a high Earth orbit, and ...
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Is the Sun in our solar system moving or stationary?

When I was small, I read that Sun is fixed at the center of the solar system and that all the other planets rotate around it. But later I heard that even the Sun is not fixed; it moves. Is this true? ...