4 ms·

As an aside, question for astronomy / orbital mechanics experts: I've always assumed that science fiction landscapes of earth-sized planets with a huge planet o

As an aside, question for astronomy / orbital mechanics experts: I've always assumed that science fiction landscapes of earth-sized planets with a huge planet or moon in the sky, not to mention several, is basically impossible. Either tidal effects would destroy the landscape, or the planet-in-the-sky would be far enough away but too large to actually be a planet. Is there a solar system configuration that would allow that kind of landscape? Example here, from the Star Trek pilot: https://api.time.com/wp-content/uploads/2016/09/star-trek-pilot-9.jpg https://api.time.com/wp-content/uploads/2016/09/star-trek-pi...

enriquto 4y ago
> Example here, from the Star Trek pilot: https://api.time.com/wp-content/uploads/2016/09/star-trek-pi https://api.time.com/wp-content/uploads/2016/09/star-trek-pi... If you have enough zoom, you can place the camera far enough and take such a photo of our moon. With a large telescope, I guess you can even do the same thing with Venus (on a very clear afternoon). So this is by no means "impossible", this is already the planet that we live in!
- deleted 4y ago
  [deleted]
- dotancohen 4y ago
  It is implied that these are views that a human or human-analogue life form would see with the unaided eye.
orbital-decay 4y ago
It's possible... sort of. The closest distance two identical planet-sized bodies in a hypothetical binary system can be together without destroying each other is about 2.5 radii, which is pretty close and the other planet would take a noticeable chunk of the sky. At that distance they'd be very oblate and tidally locked to each other; not exactly a world friendly to biological life, and won't look like your picture either.
Tuna-Fish 4y ago
The most sensible such situation is having the action happen on a moon of a smallish gas giant. Something a bit smaller than Saturn could hold an earth-sized moon in close enough orbit to have reasonable day-night cycles even if it's tidally locked. (And those days would be a bit freaky -- unless it had a very high inclination, in such a close orbit around such a large body, there would likely be an eclipse every day at midday.)
TinkersW 4y ago
Our own moon used to be much closer(few billion years ago), and would have looked something like that.

enriquto 4y ago

> Example here, from the Star Trek pilot: https://api.time.com/wp-content/uploads/2016/09/star-trek-pi https://api.time.com/wp-content/uploads/2016/09/star-trek-pi... If you have enough zoom, you can place the camera far enough and take such a photo of our moon. With a large telescope, I guess you can even do the same thing with Venus (on a very clear afternoon). So this is by no means "impossible", this is already the planet that we live in!

deleted 4y ago
[deleted]
dotancohen 4y ago
It is implied that these are views that a human or human-analogue life form would see with the unaided eye.

orbital-decay 4y ago

It's possible... sort of. The closest distance two identical planet-sized bodies in a hypothetical binary system can be together without destroying each other is about 2.5 radii, which is pretty close and the other planet would take a noticeable chunk of the sky. At that distance they'd be very oblate and tidally locked to each other; not exactly a world friendly to biological life, and won't look like your picture either.

Tuna-Fish 4y ago

The most sensible such situation is having the action happen on a moon of a smallish gas giant. Something a bit smaller than Saturn could hold an earth-sized moon in close enough orbit to have reasonable day-night cycles even if it's tidally locked. (And those days would be a bit freaky -- unless it had a very high inclination, in such a close orbit around such a large body, there would likely be an eclipse every day at midday.)

TinkersW 4y ago

Our own moon used to be much closer(few billion years ago), and would have looked something like that.