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 was the Moon's “Evection Resonance”?

Ward et. al define the evection resonance of the Moon with the Earth and Sun as: occurring when the lunar perigee precession period equals one year. Does this simply mean that the angle formed by ...
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Precision in the space navigation [migrated]

I am curious about the precision NASA and other agencies have in the space navigation. Are they always accurate to the meter in position they aim for; in mission like the recent rover landing on the ...
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How to choose initial state vectors for a resonant orbit numerical simulation?

How do higher numbers affect orbital resonance? is a really interesting question, and I thought I would try to do a simple numerical simulation of various resonance ratios to see if some are ...
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Was Newton the first to mention the orbital barycenter?

A barycenter is the common center of mass of an orbiting system. Here is a illustrative gif from wikipedia: The first mention of something like a barycenter that I could find is in a translation of ...
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How to track orbit of an exoplanet?

I was wondering if there is an established method to keep track of the orbit of an exoplanet assuming we know a - the semi-major axis of the orbit, e - the eccentricity of the orbit, and i - the ...
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Galactic orbits and distance between stars

In the context of whether or not nearby stars were created from the same nebula, this answer states: imagine two stars with very similar orbits, one with a period of 200 million years and the other ...
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Do moons of rocky oblate planets migrate to low inclination over time? If so, does the time it takes depend on the Moon's size?

Discussions elsewhere suggest that this happens and that smaller moons would tend to low inclination with respect to the planet's equator faster than larger ones. For example, Mars' small moons are ...
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Do the orbits of planets change? Where is the data for this?

Everything in the space is moving all the time. Do the orbit of major Solar Systems planets, Mercury to Saturn change? Just like Moon's orbit around Earth changes. How often, how small or big is the ...
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What is the antonym of “closest approach”?

The distance from Earth to Mars, during their closest approach, is about 55 million kilometers. At their furthest apart, that distance would be about 401 million kilometers. Distance at closest ...
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Classical Mechanics : Interaction Sun Radiation Pressure - Gravitation

I have a theoretical problem that merges the effects of a gravitational field and the Sun radiation pressure. The problem goes as follows: A spacecraft orbits the Sun in absence of any other body ...
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Sun's and planets' inclination to the Invariable plane

What are the inclinations of all major Solar system planets (Mercury to Pluto) to the invariable plane? Looking for accurate data calculated on them. Also, What is the inclination of the Sun to the ...
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Moon's and nodes' inclination to the Invariable plane

Moon is inclined to the ecliptic 5.14 degrees. Earth's inclination to the invariable plane is 1.57869 degrees. What is the Moon's, and node's inclination to the invariable plane? Since the Moon has an ...
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What calculations show that Comet Shoemaker-Levy 9 orbited Jupiter for several decades before its spectacular impact? (Chodas, Sekanina & Yeomans)

This answer to A moon in eccentric orbit dipping below Roche limit includes the following about Comet Shoemaker–Levy 9 Here is a nice figure of its last passes: I looked up "fragment A" in ...
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Calculating the Angular Momentum of a planet

I want to calculate the Angular Momentum of any planet at any point on the orbit around the Sun. Example: I want to calculate the Angular Momentum of Pluto today, on Jan 27, 2021 00:00:00 Hrs Where ...
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Did Aliens make Oumuamua?

Dr. Avi Loeb, the distinguished astrophysicist and chair of Harvard's Astronomy Program, just published a book called Extraterrestrial: The First Sign of Intelligent Life Beyond Earth. In the book, Dr....
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Semi major axis of an hyperbolic orbit

The semi major axis (a) is not immediately visible with an hyperbolic trajectory but can be constructed as it is the distance from periapsis to the point where the two asymptotes cross. Usually, by ...
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Are there any stars that orbit perpendicular to the Milky Way's galactic plane?

Most stars orbit in the Milky Way's galactic disc. But is it possible for one to orbit perpendicular to it? Here on Earth since we're inside the galactic plane we can't get a good view of what the ...
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Why is dark matter required?

I read somewhere that the galaxy is spinning too fast (in places). Therefore, there must be dark matter. What are the equations that explain how fast the galaxy should be moving, and how are they ...
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Are there any moons of minor planets that orbit at high inclination to the plane of rotation of the parent body?

It occurred to me that one of the ringed asteroids or minor planets may answer this question about the alignment of planetary rings. However, it appears that the rings of Chariklo, Haumea and Chiron (...
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Kepler's Law, focal points - Heliocentric or Barycentric?

It is known that all the mass in the Solar system moves around the Barycenter. For the two focal points in Kepler's law; is the first focal point $F_1$ a Heliocenter? Or is it actually a Barycenter? ...
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Trying to calculate terrestrial line of sight duration to a fictional satellite

Let me preface this with most of my understanding or orbital mechanics come from playing Kerbal Space Program. I understand most of the terminology, and a good chunk of the math, but not all of it. I'...
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When will Callisto be in orbital resonance with the rest of Jupiter's big moons?

The four Gallilean moons of Jupiter (from innermost) are Io, Europa, Ganymede, and Callisto. Io, Europa, and Ganymede are in a 1:2:4 orbital resonance. Callisto's orbital period is 16.689 days, which ...
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Semi-major axis vs. apogee and perigee of orbit

This article on Wikipedia about Sedna states that its aphelion is 937 AU, its perihelion is 76 AU and its semi-major axis is 484 AU. I would have expected the SMA to be half of the sum of the aphelion ...
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Problem with Tychonian model of geocentric universe?

Just like other proposed models of universe in history, Since Tycho's aren't being used, there MUST be any flaws in compare with widely agreed today understanding Is there any detailed reference ...
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Why are asteroids with circular orbits rare?

Regarding this excellent question by Swike: Why are asteroids with zero orbital inclination rare?, I recently proposed that orbits with zero inclination are rare as a natural result of the statistical ...
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Moons with curlicue paths around our Sun?

I naively believed that since our Moon orbits Earth, and since Earth orbits the Sun, the path our Moon might take around the Sun would be this type of epitrochoid curve: I was surprised and delighted ...
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Does anything orbit the Sun faster than Mercury?

Mercury's orbital period around the Sun is about 88 days. Comets and other things have gotten closer to the Sun than Mercury does. But has there ever been an asteroid or some other body discovered ...
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Are there any bodies in the solar system whose rotation is almost tidally locked or barely tidally locked?

The Moon's rotation is firmly tidally locked to the Earth and the Earth's rotation is firmly tidally unlocked with respect to the Moon. I gather that Mercury's rotation is tidally locked in a 3:2 ...
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Is a double quasi-binary system valid?

I was messing around with 4-body problems, and discovered a system where a close binary and a regular binary pair orbit each other. The regular binary gets disrupted every few orbits and one star ...
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Constants of three body problem(2 fixed centers)

I was solving two fixed centers problem and got answer in quadratures. After that i want to find constants of motion. First one is full energy - E. Second is $p_{\varphi}$. And third one comes from ...
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“Periapsis” or “Periastron”?

I was taught from Bate Mueller and White, that the proper terms for the closest and furthest points and distances from a body in orbit around another unspecified body are "periapsis" and &...
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Callisto's orbit: circular vs JPL is periodic 4 degree error, why?

I am approximating the azimuthal angle of Callisto from Jupiter or the Jupiter+moons barycenter using a constant angular speed circular orbit. This differs from the JPL ephemerides by only about 4 ...
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How to derive Kepler's 1st Law?

I was going through the derivation of Kepler's 1st Law in the textbook "An Introduction to Modern Astrophysics" by Carroll and Ostlie. From there, I got stuck in a few places in their ...
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How small could an orbital system be in our solar system?

Answers to How does the Sun's gravity have so much force and pull on the solar system? How does it scale? Newton's law of gravity scales on orbits so that we can theorize very small orbits with very ...
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How does the Sun's gravity have so much force and pull on the solar system? How does it scale?

Watched this video: https://fb.watch/1U0vCFBr0L/ Ok, so the distances are huge. And the sizes are much different. But I wonder how then the sun keeps the planets etc. orbiting it. If we swap out all ...
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Throwing a baseball from orbit to the earth

I just read a thought piece about what a war in space may look like, and it changed my thoughts on what orbit actually is. From what I read about orbits, it sounds like going faster in the velocity ...
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what would the mass and density of Sirius A be if the mass of Sirius B is roughly the same as the Earth?

I am writing a blog post and while I am interested in astronomy I havent done any physics like this since high school. My question is: what would the mass and density of Sirius A be if the mass of ...
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If suddenly “knocked” or perturbed from its orbit, would gravity eventually return the Earth to its original orbit?

If suddenly "knocked" or perturbed from its orbit, would gravity eventually return the Earth to its original orbit? I am curious as to whether this is even possible. It seems to me that ...
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How does an object at L1 stay at L1?

I've recently been reading about the DSCOVR satellite, and I'm confused about it's orbit. According to NOAA A million miles away, DSCOVR orbits a unique location called Lagrange point 1, or L1. This ...
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Does the Honey moon have a precession problem?

In Steven Colbert's interview with Neil deGrasse Tyson after about 03:16 the following is explained: But wait, all the moons - all the full moons of the year have ...
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Will the United States Presidential Election (day asteroid) be back soon?

My google news feed is awash with mono-themed articles, including a near Earth asteroid that passed by around election day 2020 in the US. We can all hope that neither will lead to an extinction level ...
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What are “non-Keplerian” orbits? What are some familiar examples in our solar system, and can some still be closed?

This excellent answer to Forms of stellar orbits around the galactic center invokes the following concepts: non-Keplerian orbits closed orbits I have a fairly good idea what these mean and so might ...
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Help understanding why these two sub-Hill sphere moon stability limits are so different?

Comments under this answer to What orbital period would produce one New Moon (and one Full Moon) each year? What other effects would this produce? link to Stable satellites around extrasolar giant ...
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Why doesn't Earth's leading tidal bulge cause the Moon to start spinning in the opposite direction than its original spin?

Please refer to the image below: My question is, why doesn't Earth's leading tidal bulge (encircled in the green circle 1) pull on the moon's tidal bulge (encircled in green circle 2), leading to a ...
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Easy interactive visualization of orbital elements

To get a grip on orbital elements, I'd like to play with a ready interactive visualization like in Universe Sandbox. E.g. drag the inclination slider and see immediately what happens to the satellite ...
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Orbital Mechanics: where can I find initial conditions for orientations and angular rates of planets in our solar system?

I am looking to write the equations of motion (EOMs) for a 6DOF analysis of our solar system. I want to integrate the equations forward in time, and need a complete set of initial conditions to do so....
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How do different formulas for calculating the mean anomaly of an elliptic orbit correlate?

I need to calculate the mean anomaly of an elliptic orbit at a specific point in time. I found two different formulas for $M(t)$ and I'd like to know how they correlate and if they result in different ...
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Why doesn't sunrise shift as we revolve around the sun (ignoring seasonal variations - so at the equator) [duplicate]

If the Earth rotates at a constant speed why doesn't sunrise change as we orbit the Sun? For example if viewing the Earth's orbit from above at time N let's assume the Earth is at the 3 'o' clock ...
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Cannot identify mistake in calculating orbital eccentricity vector; magnitude equals one instead of zero (with python code)

I have a gravitational nbody simulation, for which I would like to determine various orbital parameters. For each body, I have 3-D vectors (x,y,z -space) for position, velocity, and acceleration. I am ...
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Small changes to Earth's orbit caused by a large impact on the Moon

Is there any scenario where a large impactor striking the far side of the Moon would perturb the Earth's orbit enough to reduce the distance from the Earth to the Sun and still remain within the ...

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