Questions tagged [orbital-mechanics]

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

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3
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4answers
72 views

Earth-sized Moon with Host Planet launched from Star System

Could a planet with the size and characteristics of the Earth orbit a gas giant and would the earth-like moon be able to maintain its orbit if the gas giant went rogue and was launched from its host ...
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3answers
570 views

Is it possible for a moon to stay on the same side of its planet relative to the sun?

I'm building an earthlike world that has a moon orbiting a gas giant. Is it possible for the moon to always be between the planet and the sun? Also, is it possible for a moon to rotate around its own ...
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6answers
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I want ten Earth-years long day on my planet. Can I have it?

I need ten Earth years long day-night cycle on my planet. Hemera is a world I am creating as a setting for my story. Name comes from Greek deity - personification of Day. Needs of storytelling have ...
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2answers
88 views

Could co-orbital planets also be double planets?

Double or binary planets are a really cool science fiction idea. A second Earth hanging ominously in the sky. Co-orbital or trojan planets are also interesting in that you have them on more or less ...
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3answers
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How close an orbit could you get to Earth with a planet-sized object/ship without severely disrupting Earth's orbit?

My idea involves an alien spaceship inside a roughly Earth to Mars sized/massed planet, but the whole planet is displaced when the drive is activated. If you wanted to travel back to our solar system ...
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2answers
372 views

Making the exoplanet with the most complicated seasons

I was wondering how/if it would be possible to create an earth-like (atmosphere, gravity, average temperature, etc. are close enough) rocky exoplanet with more than two or three significant ...
5
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0answers
98 views

How to Calculate Apparent Magnitude/Brightness of Planets from Within the same Solar System

I'd like to be able to determine the appearance of the night sky from an Earth-like planet, in a solar system with multiple other planets, moons, and other bodies. Here on Earth, we can directly ...
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1answer
115 views

Binary Star System Build - Alpha Centauri

I'm not sure if this site or Astronomy would be better, but I figured I would try here instead. I am attempting to create a [semi]plausible star system in Alpha Centauri for a series. The system was ...
3
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1answer
140 views

If Earth had a sideways axial tilt (like Uranus), would Earth still have tornadoes?

Imagine Earth was hit hard by some force so devastating that Earth now has an axial tilt of 90.0 degrees, a far cry from the usual 23.5 degree. The same force somehow eliminates the Moon. In my story, ...
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1answer
103 views

Minimal mass of an Earth-like satellite to seriously deter space travel?

I want to write a story taking place on the natural satellite of a gas giant, with said satellite being massive enough to prevent, or at least strongly deter, space travel, such that the resources ...
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7answers
142 views

What kind of lunar orbit would cause a total solar eclipse to happen once a day?

The eclipse needs to be visible from at least one region on the planet every revelation and last about one hour.
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2answers
70 views

Are Orbital Rings feasible to construct in another star system?

In this universe, Earth had a couple orbital rings during the construction of the colony ships that were sent to Alpha Centauri. Humanity has achieved fusion power and efficient space flight (1g ...
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0answers
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How long to become a habitable planet

I am creating a world for Sci Fi story in which I am trying to have two non-tidally locked earth sized planets in a binary orbit around Alpha Centauri A. The only way I can think of this happening is ...
3
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1answer
126 views

Binary planets that are not tidally locked

The story takes place in Alpha Centauri, with this binary orbiting just over 1 AU from Rigil Kentaurus. The star system will tightly packed, but following the 10 Mutual Hill Radii separation setup. ...
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4answers
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What are the odds that an alien spaceship entering a low Earth orbit would collide with an orbiting body?

After centuries of careful search and travel, some intrepid extraterrestrial explorers have finally found another inhabited world! Elated with their discovery and exhausted after their long journey, ...
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10answers
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Can a moon orbit a planet's southern pole?

I am interested in the idea of a moon orbiting only the southern pole of a planet. Could it theoretically be possible (though unlikely) that a moon would, for instance, orbit a planet parallel to the ...
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1answer
127 views

How Would These Planets Affect Earth's Eccentricity?

A cleaner, narrower-focused improvement of How This Alternate Solar System Influences the Milankovitch Cycle, so not a duplicate. For further clarification, eccentricity is the shape of a planet's ...
5
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2answers
189 views

What if Jupiter and Mars swapped orbits?

I am wondering how will it affect earth or none at all. Seeing that Jupiter by far is a gas giant and has really strong gravitational pull while Mars is mostly dormant, weak gravity and a terrestrial ...
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3answers
98 views

Would tidal acceleration mean doom for this system?

So we have a Super Earth of ten Earth masses, just on the threshold, and it has three Mars sized moons (so a mass ratio of 100/3, more than Saturn Vs 3 Earths). They go 40,000km, 100,000km, 250,000km ...
3
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4answers
522 views

After surviving a black hole/wormhole, what are the chances of Earth start orbiting in a new solar system?

In the event of our sun suddenly becoming a black hole or wormhole of sorts. It transports the earth to another solar system similar to ours. Would it be possible for our planet to start circling ...
2
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1answer
74 views

Habitable Planet in the L2 Lagrange Point of a Hot Jupiter

If orbiting in the L2 lagrange point of a large planet (doesn't actually have to be a hot Jupiter, just large enough to fully shadow the smaller planet), how close could you get to the host star ...
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12answers
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Habitable Planet with Highly Eliptical Orbit

Would it be possible for life to develop on a planet with a highly elliptical orbit? (Similar to a comet, but possibly less extreme.) If so, what conditions would be necessary and what would the life ...
4
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2answers
130 views

Space elevator off Europa without running into a nearby moon?

Would it be possible to build a space elevator off Europa? (The space elevator would only be for the purpose of getting items out of Europa's gravity well relative to Jupiter. At that point, the ...
6
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4answers
152 views

Could some natural process on a moon do enough stationkeeping to sustain an impossible orbit?

I have several stories where I've wanted a moon in some weird orbit that is not allowed by orbital mechanics. In the past, I've had to change stories to bow to physics. Today, I had a thought while ...
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2answers
115 views

The major effects on the habitability of exomoons orbiting this Brown Dwarf

I'll need to give some background to this question. I'm interested in the idea of a densely inhabited star system, and having large exomoons is one way that they can all orbit roughly at the same part ...
2
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1answer
63 views

General effects (and narrative practicality) of a moon with an extreme elliptic orbit

This is more for fluff and illustrative exotica, but I'm keen on an idea where my new world has a moon that orbits elliptically, but has a fast inward close orbit followed by a longer round trip the ...
3
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1answer
76 views

Ideal sun type and corresponding effects for a terrestrial planet with 256 days in a year?

The planet has 256 days in a year, split up into eight months, each with 32 days. My planet is a bit smaller than Earth: Think, enough space for the continents of Earth’s western hemisphere and the ...
3
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1answer
61 views

plausibility of this double planet system? [duplicate]

So, I'm about to start a new worldbuilding project for a fantasy world, but I want to try to make the basic world at least somewhat plausible; the magic in the setting is going to be pretty low-key, ...
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4answers
127 views

Is this planet-moon system possible?

The planet is 10 Earth-Radii, with a 1 Earth Gravity value. It is a habitable planet. It has a thin atmosphere. It also has 3 moons and a ring system. The moons are rather large. The largest one is ...
6
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1answer
95 views

What would the effects be on a planet whose moon orbits at a speed just faster than a geosynchronous orbit, so there are more months than days?

Would anyone be able to check some math/ let me know if I'm thinking of this the correct way? I had an idea of the moon appearing basically stationary in the sky, but in fact it orbits just faster ...
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2answers
101 views

Inverse orbital direction

Is it possible that a planet/moon will have inverse direction comparing to the rest orbiting material? For example Mars would go in counter direction comparing to other planets in solar system. If ...
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5answers
8k views

Can two moons have intersecting orbits yet be guaranteed not to collide?

Working on a D&D campaign. As a physics nerd, I'd like the orbital mechanics of the planet, its sun, and its moons, to follow standard Newtonian/Keplerian mechanics. I'm trying to come up with ...
5
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2answers
84 views

Navigation on a planet with an eccentric orbit

On this planet, there is a nomadic tribe of humans who are the descendants of unwilling colonists from thousands of years prior. They are a nomadic tribe because of the incredibly extreme seasons, ...
4
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1answer
154 views

Are elliptical rings feasible?

Around a rocky planet or small gas giant, could there be a system of rings that follow an elliptical orbit? I have used a gravity simulator (this one) to test it, but the way it handles its particles ...
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2answers
67 views

Feasibility of extra-lunar capture

Using our own Earth and Moon as a template is it possible for a second large body (One quarter to a third of the Moon’s Size) drifting close by to be captured in a stable and permanent orbit? ...
9
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4answers
203 views

How can an Earth-like moon meet these angular diameter conditions?

NOTE: If there is anything about this question that needs clarification or editing, please don't hesitate to let me know in the comments. Get ready, because you're in for quite a ride. I have tried ...
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2answers
149 views

Binary World Mechanics

I’m trying to develop a realistic system with a limited understanding of astrodynamics. Is it possible to have two binary worlds capable of sustaining atmosphere and complex life orbiting one another ...
6
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5answers
379 views

What star can give an earth-like planet a 1-day year?

I did the orbital period for a planet orbiting a mass = 1 sol with a 24-hour year, it’s got a semi-major axis of 1.82 million miles - far and away beyond the Roche limit, still beyond the corona, but ...
2
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1answer
84 views

What is the highest theoretical escape velocity a 2 billion metric ton vehicle can achieve using a >20° gravitational slingshot?

I want to send a flying saucer (a $\frac{1}{10}$ scale Independence Day City Destroyer - calculated as a sphere cap 112m high with 1.2km segment radius, $\rho$ about 43.3kg/m3) away from the sun as ...
5
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2answers
158 views

Creating “Sunfall” on the moon of a gas giant

I'm attempting to figure out the orbital physics of a system that has a habitable body that has intense periods of waxing and waning sunlight. I've come to the assumption that the best body for this ...
7
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9answers
1k views

Realistic ways a Planet or Large Moon could have Variable Day/Night periods

Hello I imagine this is a pretty straightforward question, perhaps already covered in another post, but I wanted to get extra perspectives and options for achieving this type of planet or moon. So ...
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2answers
118 views

Can an Unstable Ternary Star System Last Several Hundred Years?

After reading the following question, I know that there are not that many solutions to the 3-body problem, and I know that a ternary system is unstable. The 3 stars all orbit each other in a rotating ...
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3answers
5k views

Can planetary bodies have a second axis of rotation?

Is it possible for a planetary body to have a secondary axis of rotation? For example let's say there's an Earth-like body that is spinning with its North Pole facing the Sun. Imagine that the North ...
0
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1answer
684 views

Stabilizing Synchronized Orbit

The planet in my story, Ser, is actually in reality a moon orbiting a larger body called planet Rea. Ser is located in the L1 Lagrangian point, which means it takes the same amount of time to orbit ...
7
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2answers
193 views

What are the size limits on an spin-gravity space station?

A spin-gravity space station, a ring-shaped structure that creates a faux gravity on the inside of the ring via inertia, has been depicted as no bigger than a house and as massive as a solar system. ...
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7answers
2k views

Gravity on an Orbital Ring

Added 9-15-19: Thank you all for your comments. I will be reading them through carefully. I have quickly skimmed through the answers and I do appreciate your corrections on terminology and ideas, and ...
4
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1answer
57 views

A Stable Red Giant Trinary System

In an alternate universe, we have a spot in the Orion Arm where we have nine Earth-like planets orbiting three red giants. Judging from the size and luminosity of each star, it's been conferred that ...
7
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3answers
2k views

Moons that can't see each other

Could 2 moons that orbit same terrestrial planet never see each other if they orbit the planet at same time? Moons have different mass and gravity.
9
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2answers
305 views

Is there a website that will run orbital simulations because I don't have a PhD in math

I'm just trying to write a RPG adventure for a sci fi company. So when I have to figure out what kind of orbits, masses, major axis, etc are needed for the system I need to design and I see: $T=2\pi$...
5
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2answers
170 views

What could cause a planet to be in shadow for a 6 earth month period every couple of earth years?

My previous question ruled out having a moon orbiting a gas giant. I've got an interesting ecosystem (my bad, biome was the wrong word) that evolved based upon the idea that the world is eclipsed for ...

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