106 votes
Accepted

Can I produce a true 3D orbit?

There are no known orbits of this kind, but they aren't proven to be impossible. You need to have 3 objects in order to have a 3d orbit, and it's known that the general 3-body problem is chaotic and ...
Cort Ammon's user avatar
  • 132k
83 votes
Accepted

Can two adjacent, life-sustaining planets orbit a star such that they are rarely near each other?

You could put both planets in the habitable zone on horseshoe orbits. Janus and Epimetheus orbit Saturn on this type of orbit. From the point of view of one moon, the other follows a horseshoe shape ...
Sean Raymond's user avatar
  • 3,509
77 votes
Accepted

How fast could earth orbit the sun without its orbit changing?

About 30km/s; that it to say, the velocity cannot change at all if you wish to maintain the same orbit. Every circular orbit is associated with exactly one orbital velocity. Every general elliptical ...
Logan R. Kearsley's user avatar
72 votes

Why would it be unfortunate for a day length to vary in a planet; other than that Java API developers need to work a few hours more?

It really bugs them What you've probably misunderstood is what the term "Java developer" actually denotes. Java developers are a small mammal similar to civet cats in Indonesia both in physical ...
nullpointer's user avatar
  • 8,689
66 votes
Accepted

Is it possible to have a planetary system with planets having perfectly synchronized orbits?

Is it possible for such a system to exist? I'm sorry, but no. At least not according to orbital mechanics as currently understood. Kepler's third law of planetary motion is one of the old workhorses ...
user's user avatar
  • 29k
61 votes

Is space piracy orbitally practical?

Building on Hariz Rizki's answer, your actual space pirate isn't going to be a swarthy, one legged man in a spacesuit with a parrot on his shoulder, but rather a well dressed functionary at the Deimos ...
Thucydides's user avatar
  • 97.7k
57 votes
Accepted

Is it possible to orbit inside a gas giant?

It would lose speed due to drag and fall in. If you're thrusting to maintain speed, just fly like a plane and don't try to orbit. The hypersonic speed of orbital velocity would be conspicuous anyway, ...
JDługosz's user avatar
  • 69.5k
56 votes

How do you non-catastrophically reduce the mass of the Sun by half?

C. Must not create any phenomena that would have devastating consequences on life on the planets (i.e.: no radiation, excessive heat, energy surges) except for the diminishing of the Sun's current ...
The Square-Cube Law's user avatar
53 votes
Accepted

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

Ok, so you say 'Harmonic Orbits', but actual Space-Talking-Dudes call that 'orbital resonance', and it's the solution to your problem. We've got an example of something ALMOST exactly like what you'...
Morris The Cat's user avatar
52 votes
Accepted

How could a planet have erratic days?

Binary star. If you have two sources of light, you will have 4 options for night and day: double star day, two single star days, and night. These will be predictable but for a complex orbit the ...
Willk's user avatar
  • 305k
50 votes
Accepted

Could two planets follow the same orbit and never "see" each other?

I assumed, based on the limited knowledge I have on the subject, that all star systems have ellipsoidal orbits (the star being in one of the two focal points) just like our own You are right, this is ...
L.Dutch's user avatar
  • 287k
49 votes
Accepted

Is space piracy orbitally practical?

Just because you can see pirates coming, doesn't mean you can stop them I'm going to make some assumptions about how your spaceships work. The average distance from Earth to Mars is 225 million km, ...
kingledion's user avatar
  • 85.4k
45 votes

Can planetary bodies have a second axis of rotation?

I asked this same question, on the physics stack. The answer is that a body can have only one axis of rotation. Below pasted is the link to the question and the answer I picked. https://physics....
Willk's user avatar
  • 305k
43 votes
Accepted

Can 3 planets rotate around each other like this?

In theory, yes, this is possible. In practice, it would be a rare thing to encounter, just because the laws of nature can be fickle and somewhat unpredictable. I'm going to call the planet your ...
PipperChip's user avatar
  • 32.3k
39 votes

Is it possible to orbit inside a gas giant?

Like JDługosz wrote, what will cause problems in the scenario you describe isn't so much your orbit as the fact that you are within the gas giant's atmosphere. I'm going to use Jupiter here to have ...
user's user avatar
  • 29k
39 votes
Accepted

How to create an annual celestial event for a world

Two moons are in orbital resonance You can have your two moons be in a m:n orbital resonance, the way that Io and Jupiter are. That way, at some time period $nT$ where $T$ is the orbital period of ...
kingledion's user avatar
  • 85.4k
39 votes

How do you non-catastrophically reduce the mass of the Sun by half?

Wormhole [A,C,D,E,F,G] A traversalable wormhole would be an excellent mechanism to remove mass from the sun. A wormhole is consistent with general relativity while avoiding all of the pitfalls of ...
Skek Tek's user avatar
  • 911
38 votes

Is it possible to have a planetary system with planets having perfectly synchronized orbits?

The only way such an arrangement could exist is having external planet being the heaviest and the others each in L1 point of next outer one. Unfortunately such an arrangement is not stable, so it ...
ZioByte's user avatar
  • 17.5k
36 votes

Is space piracy orbitally practical?

Lots of people here, including the OP, are worrying over the capabilities and tactics of space pirates, but the question fundamentally deals not with those particulars, but rather the economical and ...
Adam Wykes's user avatar
  • 2,904
36 votes
Accepted

Where is the best place to park your damaged spaceship, longterm?

The orbits of larger moons should be stable and mostly clear of hazards. I'd recommend placing your ship at one of their Trojan points. Just pick the one most convenient. Closer to planet, not already ...
Ville Niemi's user avatar
  • 43.2k
36 votes

What do Martians use for months and weeks?

Please remember that time is an arbitrary concept Without any outside influence, the very first basis of time is the "day" consisting of a period of "light" and a period of "no light" that we ...
JBH's user avatar
  • 123k
35 votes

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

You should have a look at Janus and Epimetheus. They are two moons of Saturn that exchange orbits approximately every four Earth years. This setup is probably not stable for more than a few billion ...
The Square-Cube Law's user avatar
34 votes

Could two planets follow the same orbit and never "see" each other?

Circular orbits are not practically possible From Astronomy.SE, there are a variety of reasons why orbits are not circular. There is relativity, there is planetary flexing with gravity, there is ...
kingledion's user avatar
  • 85.4k
34 votes
Accepted

How can I launch a projectile to hit something in orbit, using only geological structures and power sources?

It doesn't seem to be possible using "normal" geology. You'd need a supervolcano to attain the required energies, and "piloting" one with the required precision doesn't look doable. You need to score ...
LSerni's user avatar
  • 55.3k
32 votes
Accepted

How much warning will the Earth get if an asteroid that will hit earth "appears out of nowhere?"

According to your diagram, the 20-km asteroid pops out of nowhere while less than 0.2 AU from earth, and 6 months before impact. It is at about 1 AU from the sun, thus presenting a well-lit half-...
PcMan's user avatar
  • 26.3k
31 votes

How short can Milankovitch Cycles be on a world with a stable orbit?

Don't. Please just don't. I have no idea how short such a cycle can be, but I can tell straight away that the idea of people capable of interstellar travel and colonization of new worlds not noticing ...
Ville Niemi's user avatar
  • 43.2k
30 votes
Accepted

How would a moon in geostationary orbit appear to wax and wane?

In one day you would see the full cycle (if you can see it) So if you stand a little distance from a lamp holding a ball at arms length, then turn around, you will see the phases on the ball. This is ...
Lio Elbammalf's user avatar
30 votes
Accepted

Is it safe to orbit HDE 226868?

X-ray radiation at the orbit of HDE226868 Cygnus X-1 is famous as one of the most powerful X-ray sources in the sky. According to the US Naval Observatory, the max flux of Cygnus X-1 (near the bottom ...
kingledion's user avatar
  • 85.4k
30 votes

Where is the best place to park your damaged spaceship, longterm?

A simple extremely high orbit, such as the aptly named Graveyard Orbit - These orbits are really high and designed so that the satellites will be there for a very, very long time. An orbit should be ...
Andon's user avatar
  • 11.6k
30 votes

How fast could earth orbit the sun without its orbit changing?

If the Sun were more massive than it is now, then the Earth would have to move faster to maintain the orbit that it currently has. The formula for the rotational velocity is $v^2$ = (G • M) / R, ...
Itsme2003's user avatar
  • 402

Only top scored, non community-wiki answers of a minimum length are eligible