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Questions tagged [orbital-mechanics]

For questions dealing with how bodies interact with each other in space via gravitation.

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At what rate does my planet become tidally locked?

I am designing an alien planet for a speculative evolution project. It is slightly less massive than Earth and is orbiting around a red dwarf, within the Goldilocks zone. It takes 220 Earth days to ...
Ambjörn's user avatar
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3 votes
1 answer
200 views

Binary planets and dual moon alignment occurring once every 200 years

I am trying to figure out a 200 year cycle where Binary planets share 1 moon Planet 1 has its own moon that maintains orbit around it. The cycle would be as illustrated below. Moon 1 would belong to ...
Keith Hayes's user avatar
5 votes
2 answers
153 views

How would be a Lunisolar Calendar with 2 Moons?

The world I'm building it's a Super-Earth named Tempus, and it has 2 moons in an orbital resonance. One of the moons, named Tidra Moon, is closest to the planet and basically has the same influence on ...
JahJahs's user avatar
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3 votes
1 answer
341 views

How much mass could be added around the Earth before the Earth's orbit around the sun changed?

In the not too distant future Earth will enter its golden age of industrialization and construction. Pulling raw materials from other planets (not from Earth), humans begin building mega structures ...
JBH's user avatar
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2 votes
1 answer
93 views

Climate on a tidally Locked Moon

Im working on a world building Project that is based on a moon surrounding a gas giant. The moon in question is referred to in the simulation as "Melorn" and marked in yellow. There are ...
Zadai.Fehbiab's user avatar
6 votes
0 answers
122 views

How do Hill spheres work for binary planets?

A small moon is able to maintain a stable orbit around a planet at just under half the radius of the planet's Hill sphere. Most of Jupiter's moons are in this configuration, possibly made more stable ...
Charles Rogers's user avatar
1 vote
2 answers
210 views

I have a world with two moons, and I was wondering how often they would both be full at the same time

As I said in the title, I have a world with two moons. One has an orbital period of 17 days Earth days (Moon 1) while the other has an orbital period of 57 Earth days (Moon 2) and the planet they are ...
Jack Kibatsume's user avatar
1 vote
1 answer
112 views

What are some things to keep in mind while designing a binary planet system with a sun-like star? [closed]

My planets are both the same size as Earth, with about the same water:land ratio. They are tidally locked to each other, but not the star. I don’t know much about planets and orbits and other things ...
Zona C's user avatar
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5 votes
3 answers
875 views

How is this possible: a moon with A) large apparent size B) that spins C) spins in a 5:1 spin-orbit resonance?

I wanted to give my planet a moon that spins every SIX days and waxes-wanes every THIRTY days. The bad news: Luna always shows the same face to Terra because of something called tidal locking ...
wokopa's user avatar
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5 votes
0 answers
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What are the orbital perturbations needed to destabilize a system to the point of taking some bodies out of resonance and kicking out another?

I have a gas giant with a mass of $1.63314\times10^{27}kg$ and a radius of 66,559.052km and orbiting it are 4 moons. It orbits a star with 0.86M☉ at a distance of 5.03AU My question is what ...
Pointy Orb's user avatar
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2 answers
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Can you have a moon that rotates 21 times per orbit?

I want to avoid having my earthlike moon of a gas giant be tidally locked. Now I know that 3:2 or even 5:2 resonance is possible, but what about 21:1 for my moon? Is that too many rotations per orbit ...
www's user avatar
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3 votes
2 answers
86 views

How far apart ought my type-S binary stars be if each is to host a stable planetary system?

Consider a G-class star (0.9457 Msol) as the primary and a M-class dwarf star (0.4335 Msol) as the secondary. If I want a stable planetary system around each (particularly the G-class), then how many ...
Ylahris's user avatar
  • 487
1 vote
3 answers
231 views

How to build a world with magnetic levitation?

Picture this: Alpha Centauri Cb (AC) has 14% Earth's oxygen 110% Earth's gravity A 60-hour day/night cycle 240-hour orbit (10 Earth days = 1 AC year) Eccentricity produces all 4 seasons in 4 days ...
reiterwriter's user avatar
7 votes
1 answer
287 views

Is this a plausible way for an Earth-like exomoon to have earth-like seasons?

Imagine an earth-type world orbiting a Jupiter-like gas giant roughly within the habitable zone. If the plane on which the moon orbits the planet is tilted at an angle relative to the Solar System's ...
Indoordinosaur's user avatar
4 votes
3 answers
597 views

Is that an elliptical orbit gas giant?

Let's say there was a ship that went into orbit around a gas giant roughly the size of Jupiter. It's going to have a highly elliptical orbit so it's much closer to the sun during summer than in winter ...
Joe Smith's user avatar
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2 votes
1 answer
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Could one moon appear to always follow/lead another in the sky?

Is there any way a second moon would appear to hang out near the closer one in the sky? For example always appearing either ahead of or behind throughout the year, or even alternating between those ...
Syntal's user avatar
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2 votes
2 answers
351 views

Can this Star system exist?

Can this star system with this configuration plausibly exist or not? If not please explain why it can't exist or explain its issues. Planetary system Star A 1.1 M⊙ Planets types mass semi-major axis ...
user107608's user avatar
3 votes
1 answer
490 views

Is there a way to increase the orbital period of a tidally locked moon without changing the distance to its parent?

The internet tells me that the orbital period of a planet is calculated via Kepler's third law which, to my understanding, says Orbital period = semi-major axis3 I have a gas giant (radius of 1 ...
SaintDiabolus's user avatar
0 votes
2 answers
358 views

Implications of Venus and Mars having the same mass as Earth

Could anyone advise if there have been any simulations on the long term stability of our solar system if Venus and Mars both had the same mass as Earth ? If not, is this something that can be answered ...
Adrian's user avatar
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3 votes
1 answer
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How might seasons work on Alpha Centauri Cb?

(first post from a writer drafting a sci-fi novel, so please forgive any ignorance or missteps and TIA!) Let's say Alpha Centauri Cb is habitable, under these conditions: Air quality capable of ...
reiterwriter's user avatar
5 votes
0 answers
88 views

What is the largest apparent size a moon of a habitable planet can have? [duplicate]

Inspired by this question: How large can an apparent size of a moon be? I am looking for a moon that is: a terrestrial moon with properties vaguely similar to Luna (not a binary planet, but it can be ...
casualworldbuilder's user avatar
5 votes
2 answers
464 views

Is it possible to have stable system where the moon of earth-like planet is only visible part of the year from a fixed point on a surface?

Is it possible to have a stable system wherein the moon of an Earth-like planet is visible only during certain parts of the year (seasons) from a fixed point on the surface, mimicking the way some ...
byMaelstromer's user avatar
3 votes
2 answers
276 views

Could Moon Phases work in a Concave Hollow-Earth?

I'm trying to wrap my head around how phases of the moon(s) would operate in a hollow earth. For reference, I am picturing a situation like this: In this system, the center of the hollow earth has a ...
A Herrera's user avatar
14 votes
4 answers
3k views

What considerations would have to be made for a spacecraft with minimal-to-no digital computers on board?

I'm writing a sci-fi book where the main method of travel involves collapsing a star into a black hole by putting a satellite equipped with some sort of handwaving mechanism into orbit around the star....
FlightDeck0112's user avatar
9 votes
3 answers
3k views

What would it take for a spacecraft to travel to the sun's nadir and stop?

In a science fiction future universe, spacecraft routinely travel from a distance "above" a star's north or south pole to rendezvous with planets orbiting in the star system's orbital plane. ...
Scottoooooo's user avatar
5 votes
2 answers
236 views

Very large orbit binary/trinary star systems

In my universe, Ancient Aliens once visited Earth with consequences.1 At that time they left instructions2 that 5,000 years3 in the future something would happen.4 The instructions left behind a ...
JBH's user avatar
  • 124k
2 votes
2 answers
234 views

What astronomical situation could account for the PERCEPTION of a very erratic day / night cycle for a planetbound population with limited science?

I would like to create a world that is at a roughly medieval level of scientific understanding and which - as far as it appears to the inhabitants of that world - has a highly erratic day and night ...
Curious-7's user avatar
7 votes
3 answers
1k views

Could a planet realistically share an orbit with Jupiter?

So I've been working on a project where I modify the Solar System, and I originally had a small gas planet(like 5-10 earth massses) named Juno orbiting between Jupiter and Saturn. However, as it turns ...
Nip Dip's user avatar
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0 votes
2 answers
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Question about finding an exact lunar orbit

I am trying to find a precise orbit for a moon that would allow it to always be in an eclipse. So, basically, I need help finding a formula for the semi-major axis and mass ratio that would get the ...
DanceroftheStars's user avatar
2 votes
1 answer
87 views

Feasibility of a moon-planet orbiting an F star [closed]

I'm building an earth-type planet with typically human-like people, but a few differences. The human's particular area won't have much in the way of seasons being a large equatorial island. I'm ...
RedFrog's user avatar
  • 21
3 votes
2 answers
341 views

How do I change earth's orbit so it is tidally locked to the sun? [closed]

In my world, I need to change the earth's orbit so it is tidally locked to the sun. How can I do this? No matter how unrealistic the solution—whether it be magic or what not—anything that can explain ...
NEWWORLDBUILDER's user avatar
2 votes
1 answer
209 views

Partially tidally locked planed due to elliptical orbit... Possible?

Would it be possible for a planet with an elliptical orbit to be tidally locked to a star, only for a certain part of it's orbit? If this is possible, then: could the tidally locked side vary from ...
Jacco's user avatar
  • 704
1 vote
2 answers
153 views

Reverse engineering the Hill Sphere?

I'm wondering if anyone has run into the issue of "I know the general idea of how big my moon is but not the parent planet" and how to sort of reverse engineer finding out the mass/radius of ...
Deep Stone Costco's user avatar
7 votes
1 answer
441 views

Zero energy transfer between Earth and Moon with space elevators

I'm asking this out of curiosity, mostly as a response to Space elevator from Earth to Moon with multiple temporary anchors and some of the comments and answers there. Suppose you're able to build ...
N. Virgo's user avatar
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1 vote
0 answers
27 views

When would two moons line up? [duplicate]

I am gearing up for a TTRPG (tabletop roleplaying game) and my world is a similar size to Earth with a smilier number of days. However it has two moons. One is slightly larger than our moon but it ...
Kevin Valentine Fischer's user avatar
1 vote
2 answers
419 views

Calculating distance of the frost- and ice line

To begin, my star is a K type star with 0.65 solar masses. I've inserted my star's mass in two different templates to calculate the frost line, yielding different results (2 AU and 2.68 AU). ...
Explunky's user avatar
  • 388
2 votes
1 answer
426 views

How could an Earthlike planet have two moons, one similar to the Earth's moon and the other primarily composed of carbon? [closed]

I am building an Earthlike planet that possesses two moons, one similar to the Earth's in terms of chemical composition and one primarily composed of carbon. How could these two moons form? Which moon ...
Galactic's user avatar
  • 4,454
5 votes
2 answers
1k views

Orbital Mechanics of a shell world

I've created a Neptune sized shell world with properties that I find are not typical of other shell worlds. Its gravity does not come from a gas giant or a black it was constructed around, but from ...
Seraphim's user avatar
  • 4,971
3 votes
1 answer
99 views

How do I approximate sunrise and sunset times in this simplified model of a solar system?

For a small game I'm working on I'm interested in simulating a basic celestial model for a planet, two moons and a sun. The main use is determining when specific eclipses happen and what type they are,...
Loid Thanead's user avatar
  • 1,363
4 votes
2 answers
252 views

Size of a gas giant with an Earth-sized moon

I am working on a world that is an Earth-sized planet that was captured by a gas giant planet moving inward in the solar system, then becoming a moon. Through magic and hand-waving mechanisms, the ...
tiluchi's user avatar
  • 121
2 votes
1 answer
92 views

How do I get the outer planets to meet in the night sky every 1-2 yrs on my planet?

One of the cultures in my story lives on the dark side of a tidally locked planet. I had an idea that they would mark longer spans of time by the appearance of the three outer planets in the system in ...
DMacc1917's user avatar
  • 956
3 votes
3 answers
1k views

How would an observer from a moon the mass of Earth orbiting a planet 81.3 time more massive be able to tell that they were orbiting with 1660's tech

For questions sake assume that this moon is a perfect recreation of Earth on January 1st 1660 and that the planet looks identical to our moon on the same day. The Planet would have a mass of 81.3 ...
KaiserVonMegalo's user avatar
2 votes
1 answer
98 views

How close could a gas giant be to my planet without it becoming a moon?

This is an M-type system. Let's take Trappist 1 as an example star (0.0898 Mass of the Sun) and Trappist 1e as an example planet (0.772 mass of the earth, approx 0.029 AU from the star). Assume for ...
DMacc1917's user avatar
  • 956
1 vote
1 answer
43 views

Distances needed to make this system stable

Let's take the Trappist-1 system, and specifically, I'm thinking about the star itself and Trappist 1e because it's the most habitable of the seven planets: Trappist 1 star is approximately 8.98% of ...
DMacc1917's user avatar
  • 956
0 votes
2 answers
128 views

Day/night cycle on an S-type planet

[Answered myself below] I've seen similar questions have been asked before, but the details are slightly different. Say you have a tidally-locked, roughly Earth-mass rocky planet in the habitable zone ...
DMacc1917's user avatar
  • 956
5 votes
1 answer
269 views

Could this sort of celestial system work?

I am attempting to create a pair of planets, both capable of harboring life. Which happens to also be quite colossal in design. We are talking about 10.13x the size of Earth. So the system I am ...
Bangerton's user avatar
6 votes
1 answer
361 views

What dictates whether an orbit gets disrupted or stabilised due to an orbital resonance?

Context: I've got an asteroid belt analogue situated between a Gas giant and a Super-earth. I knew about resonances, so I started calculating them and placing some of them in the belt, especially ones ...
Yulian's user avatar
  • 462
1 vote
1 answer
165 views

Could a terrestrial planet have a stable orbit of rings? [duplicate]

Planet Phileas, similar in size to Earth. Fourth star in a binary star system with a p-type orbit. Changes may be necessary and I'm open to constructive criticism. This question includes two parts. ...
raevynn's user avatar
  • 335
1 vote
2 answers
268 views

Can Integral Trees be Sailed?

In the book The Integral Trees by Larry Niven, he presents people living in a novel environment. There is a neutron star (quite old and so cooled off mostly) around a more ordinary star. And orbiting ...
Boba Fit's user avatar
  • 4,127
4 votes
3 answers
317 views

Can a rocky planet form between gas giants?

The Question I am working on filling in the planets of the Ilus system. I am setting up a strange, huge, low density, sort of habitable world in the gap between two gas giants. Is there a way for a ...
Sam Kitsune's user avatar
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