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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How to project an arbitrary elliptical orbit onto the night sky plane?

An ellipse E is arbitrarily oriented in 3-D space with the origin at one of its foci. Use the standard elements provided in the figure. Assume the reference direction $\gamma$ or $\gamma'$ is the ...
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How large were the deviations of Uranus's positon from predicted which led to the discovery of Neptune?

After Uranus was discovered and its orbit calculated, its future orbit was calculated, and its future positions as seen from Earth were calculated. And observers of Uranus began to notice that Uranus ...
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Why is the Moon's orbit so complicated?

I like to think I have a good enough understanding of astrophysics but there's still one thing that I just can't explain. Why does the Moon orbit the Earth the way it does? Many other moons in the ...
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Keplerian Elements for Approximate Positions of the Major Planets

Simple question here. I am working on something that needs to compute an orbital path using Keplerian Elements. When doing some research I came across this JPL page: Click Here. Within that link is a ...
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Understanding the JPL Ephemerides

I'm working on an animation that replicates our Solar System. I know this has been done before, but I'm working on something that requires me to make one myself. With that being said, I'm having a ...
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Why does the Parker Solar Probe slow down as the distance from the Sun increases?

Why does the Parker Solar Probe slow down as the distance from the Sun increases? Image credit: Wikipedia user Phoenix777, CC BY-SA 4.0
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Can you create an orbit in a space station using balls?

Would it be possible to spin a ball in a space station, and for it to create its own orbit for a smaller ball to rotate around it?
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What kind of triangle is formed by three unequal masses in a circular restricted three body orbit?

This answer to Are the orbits of all triple star systems at least technically unstable? mentions: There are known solutions to the gravitational three body problem that can be shown to be stable. ...
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Have meteor showers been predicted for planets or solar-system bodies other than Earth? Have attempts been made to detect them?

Per the linked Q's and A's in Why do particles from a comet that result in meteor showers spread out mostly along the comet's orbit? and it's answer, meteor showers happen on Earth when it passes ...
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Roughly what fraction of comet orbits that intersect Earths' orbit result in known meteor showers?

Per the linked Q's and A's in Why do particles from a comet that result in meteor showers spread out mostly along the comet's orbit? and it's answer, meteor showers happen on Earth when it passes ...
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Why do particles from a comet that result in meteor showers spread out mostly along the comet's orbit?

My understanding of the meteor showers that repeat yearly is that the Earth passes through the orbit of a comet that is nowhere near us, and might not even exist anymore, yet it's orbit is filled with ...
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Do Astronomers really never call Lagrangian points “libration points”?

In this answer to Who called the Lagrangian points as “Libration” points and and why was the terminology “Libration” used? I described my feeling that Lagrangian points were also sometimes called &...
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Is the vernal equinox always in zenith somewhere on the equator?

I'm trying to visualize the satellit orbital parameter "right ascension of the ascending node" (RAAN). Measuring the angle from the vernal equinox to the point where the satellite's orbit crosses ...
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Why does the closest approach of star S2 to Sgr A* not appear to be near the focus of its elliptical orbit?

Phys.org's Very Large Telescope sees star dance around supermassive black hole, proves Einstein right links to several ESO videos, including The star S2 makes a close approach to the black hole at the ...
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What was that single file line formation of flashing plane lights flying in the sky at night? [duplicate]

It was here on the west coast at 5 am pacific standard time when I went outside for a smoke when out of the corner of my eye what looks like a plane with flashing lights going across the sky when all ...
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Comparing orbits between a planet and Red Dwarf

I have a MATLAB problem, so I have an earth like planet orbiting around a sun like star and then there is a red dwarf on an elliptical orbit around the star that passes close to the planet. I want to ...
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Is this a potential planetary setup for the Alpha Centauri System?

I originally posted this on the World Building SE, but I was suggested to post it here for a better answer. I am attempting to create a [semi]plausible star system in Alpha Centauri for a series. The ...
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Determining the area of Lagrange Points

I have looked into Lagrange points a decent amount and I see many images that show the L4 and L5 locations as wide sweeping areas. Jupiter's Trojan asteroids are a good example of this. As well, L3 ...
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Planetary phase angle of Hohmann transfer

This is Question 23 from USAAAO First Round 2015. The answer is D. Can someone show how to get the answer? Calculate the planetary phase angle (counterclockwise from Earth, a = 1.0 AU) that a probe ...
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Combined mass of binary stars

This is Question 17 from USAAAO Practice Round 2015. The answer is D. It would be best if someone can detail out the workings. In a nearby star system, two stars are seen to orbit each other every ...
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How close would the sun have to get to a supermassive black hole to have Jupiter stripped and slingshot into interstellar space?

Please make whatever assumptions are needed. Assume sun approaches black hole on some sort of hyperbolic trajectory. Assume size of supermassive black hole is same as the one at center of our galaxy....
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Is a year really 365.24 days, or is it 365.2564 days like I remember?

The NPR News item and podcast Spring Starts Today All Over America, Which Is Weird includes the following: But why isn't the time of the equinox the same each year? The short answer is that the time ...
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Why are asteroids with zero orbital inclination rare?

This is a plot of orbital inclination ($i_p$) vs. semi-major axis ($a_p$) of 96944 asteroids in the Main Belt, done by Piotr Deuar. Some structure can be seen in this diagram; clumps are asteroidal ...
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How feasible would it be to get to a planet orbiting directly opposite Earth?

Imagine that in addition to Earth, there was a second planet, say of one Earth mass, orbiting the sun - but on the opposite side of the Sun, and at the same orbital radius. My question is - given ...
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Binary star system effects at the barycenter

I haven't been able to find anything on this so far. Using Alpha Centauri as the study, what events/effects ( if any ) would happen between the two stars? More specifically, between the gravitational ...
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Binary planet orbital distance

From reading various sources online, I see that some people talk about binary planets in very tight orbits (around 1 or 2 planet radii). I am wondering if it is possible for a binary planet (Double ...
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Why is there no concavity in the orbit of the moon around the Sun?

Such questions have been asked here and I have read the answers some of which are quite informative. However, I want an answer that's straightforward. I have gone through the following paper by A B ...
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How is the Sun tilted to its orbit around the Milky Way's center?

We know how the Sun is tilted in reference to its planets but how is it tilted to Sagittarius A or its orbit around it? Or isn't it tilted at all?
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Why is the asteroid belt shaped like a triangle?

So, in this question, the user JollyJoker posted this image depicting the orbits of the asteroids in the asteroid field in the comments: [ In this image, you can see that while the individual ...
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What would happen if the earth's orbit were slightly perturbed?

Suppose a rogue planet came zipping through the solar system and changed the earth's orbit a little, including the plane of the orbit. I have the idea that, in a complex system, orbits would tend ...
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Is there a verification of the solar system barycenter as it is theoretically determined?

The barycenter of our solar system is not the sun, but a changeable location outside of the center point of the sun. A often used diagram of that relation is shown below, originated from the Wikipedia ...
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What is the cycle for when the maximum amount of the Moon's apparent area is sunlit?

The Moon is defined as full when its ecliptic longitude is 180$^{\circ}$ distant from the Sun's. But what is the cycle for when the maximum proportion of the moon's apparent area is sunlit, and for ...
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Kepler's equation and eccentric anomaly

From the wiki article about eccentric anomaly follows: $$\cos E = \frac{x}{a}$$ $$\sin E = \frac{y}{b}$$ where E - eccentric anomaly, a - semi-major axis, b - semi-minor axis, P = P(x,y) a point on ...
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Scientific possibility of stationary moons for a writer of fiction

I tried to do some research to find an answer for this question before posting this but didn't find anything that I could sink my teeth into. I was wondering: if it would be possible for a planet to ...
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Can Kepler's 3rd Law be applied in higher dimensions to describe orbits (quadric surfaces)?

Motivation for asking: The 2-D orbital path of a celestial body revolving around another celestial body due to the force of gravity can be described by a conic section; this is the curve formed by ...
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In binary systems, does the speed of the objects vary as they adjust to the movement of the other object?

The speed of objects orbiting in a binary system, like Pluto and Charon, is the speed and direction of the objects smooth, or, do the objects make adjustments that are in some ways like a "tug of war" ...
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Do planets orbit the sun in ellipses because of sun movement vector?

The assumption is made that the planets of our solar system all have elliptical orbits elongated in the same direction. Further, generalized to that orbits around any object with its own orbital ...
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Could the barycenter orbit of our sun be greatly underestimated?

The radius of the suns orbit around the barycenter of the solar system is often measured to be roughly the radius of the sun. Based on the same type of bias that has made humans miss things about ...
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Could a gas giant orbit a star with a 30 year period at a distance of just 1 AU?

Assuming a star with similar properties to our sun, could a gas giant orbit it with an orbital period similar to that of Saturn, but, at a much closer orbital distance, more similar to 1 AU?
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How do I calculate the Hill radius of a star in a binary system?

Is there an easy way to calculate the Hill radius of a star in a binary system at different orbital radii where both stars are of the same mass and in circular orbit around one another’s centre of ...
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Is Earth's Surface “In orbit”?

I'm having trouble understanding relative angular/tangential speeds at increasing altitudes above Earth's surface. In particular, I find this comparison of tangential velocities on Wikipedia very ...
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What exactly is the relationship between the orbits of Neptune's moons Naiad and Thalassa?

Scitechdaily's Wild Orbits of Neptune Moons a ‘Dance of Avoidance’ [Video] links to the YouTube video Neptune Moon Dance (Naiad and Thalassa) and says: In this perpetual choreography, Naiad swirls ...
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Are the orbits of all triple star systems at least technically unstable?

Background: In the Circular Restricted Three Body Problem (CR3BP, CRTBP) some halo orbits are mathematically stable. That means that the orbit of the third body is closed, periodic, and stable ...
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How to find the Orbital Period of two Binary Planets around a Single Star?

This is kind of a weird one. Bare with me! :) Background: (Skip to the math below if you just want to answer questions) In my favorite game, Elite: Dangerous, I "own", or occupy I guess, a system ...
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Given that Kepler's Third Law as stated on most websites doesn't include mass, how does it work for planets in other star systems? [duplicate]

Kepler's Third Law as stated on websites I found while searching for "how to convert between a planet's orbital period and semi major axis" is $P^2 = A^3$ where P is the orbital period in years and A ...
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Orbital speed is (vector) sum of tangential and normal speed?

Orbital speed definition in wiki does not state clearly - it is just tangential speed component or square root of squares of normal and tangential speed (full speed vector). When we say that moon ...
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Could someone please explain to me how I can extract velocity component values from Stellarium, for a given planet?

For a project that I am currently working on, I would like to know how one could extract velocity component values ($v_x$, $v_y$ and $v_z$) for a planet from the Stellarium software. The current ...
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Would an object shot from earth fall into the sun?

Would an object shot from earth fall into the sun? If an object is shot at 107,000 km/h via rocket or otherwise, in the opposite direction to our orbit about the sun, it will be traveling at 0 km/h ...
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Propagate Earth trajectory for 1 Myr

What is the most accurate way of propagation of Earth trajectory relatively to the Sun? I need to calculate the Earth-Sun distance. Is there any library on Python? I've used before JPL Horizons, ...
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Would two Earth-like planets on opposite sides of a Sol-like star at about 1 AU be a stable configuration?

Would two Earth-like planets on opposite sides of a Sol-like star at about 1 AU be a relatively stable configuration? I understand that there are tadpole-like orbits and the two planets may not stay ...