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General questions about SpaceEngine

Posted: 03 Jun 2019 13:34
by HarbingerDawn
Trajk Logik wrote:
Source of the post Is every moon in Space Engine in a synchronous orbit with it's planet, like the Earth's moon? Shouldn't some moons have a rotation that is a different speed than their orbit around their planet which makes the planet rise and set?

Almost all moons in reality will be tidally locked to their parent planet, the exceptions will be moons that orbit extremely far away from their planet, which tend to be small, captured moons. But large regular satellites will virtually always be tidally locked. This is certainly the case with every moon that we know of in reality, and it should theoretically be the same with other moons too.

General questions about SpaceEngine

Posted: 03 Jun 2019 14:13
by N3cronium
HarbingerDawn wrote:
Trajk Logik wrote:
Source of the post Is every moon in Space Engine in a synchronous orbit with it's planet, like the Earth's moon? Shouldn't some moons have a rotation that is a different speed than their orbit around their planet which makes the planet rise and set?

Almost all moons in reality will be tidally locked to their parent planet, the exceptions will be moons that orbit extremely far away from their planet, which tend to be small, captured moons. But large regular satellites will virtually always be tidally locked. This is certainly the case with every moon that we know of in reality, and it should theoretically be the same with other moons too.

As a follow-up question, I would like to ask about moons with p-type circumbinary orbits around the barycenter of a binary planet. Are all circumbinary moons necessarily tidally locked to the barycenter? In Space Engine, procedural circumbinary moons are tidally locked to the barycenter. I would assume that most circumbinary moons would be thrown into chaotic rotations as a result of gravitational fluctuations from the two orbiting planets, similarly to the smaller moons that orbit the Pluto-Charon system.

General questions about SpaceEngine

Posted: 03 Jun 2019 14:57
by A-L-E-X
HarbingerDawn wrote:
Trajk Logik wrote:
Source of the post Is every moon in Space Engine in a synchronous orbit with it's planet, like the Earth's moon? Shouldn't some moons have a rotation that is a different speed than their orbit around their planet which makes the planet rise and set?

Almost all moons in reality will be tidally locked to their parent planet, the exceptions will be moons that orbit extremely far away from their planet, which tend to be small, captured moons. But large regular satellites will virtually always be tidally locked. This is certainly the case with every moon that we know of in reality, and it should theoretically be the same with other moons too.

What percentage of moons actually revolve in reverse direction to their parent planet's rotation?  I think Deimos does that?

General questions about SpaceEngine

Posted: 03 Jun 2019 15:13
by FastFourierTransform
A-L-E-X wrote:
Source of the post I think Deimos does that?

Both Phobos and Deimos are tidally locked to Mars. So probably no.
If you are refering to the orbital motion it is also a no. Phobos and Deimos are both prograde (they orbit in the same direction of Mars's rotation). But an interesting thing happens: From the surface of Mars it looks like Deimos moves in the opposite direction of Phobos. Maybe that's the source of what you said. Since Phobos is so close to Mars it completes an orbit in less than a martian day, which means that from the surface it looks like it is traveling fast ahead. Deimos, even if it moves in the same direction as phobos, moves very slowly due to its large orbit. That means that it lags behind of the martian surface as it rotates, so you see it moving in the opposite direction. But is just a relative rotation issue, the truth is that both move in the same direction.

General questions about SpaceEngine

Posted: 03 Jun 2019 15:39
by A-L-E-X
Ah thanks- I was wondering if it is possible for a moon to move in the reverse direction to its parent planet's rotation.  Funny thing about Phobos and Deimos, in Gulliver's Travels, the writer made predictions about the Martian moons that turned out to be relatively accurate!

General questions about SpaceEngine

Posted: 03 Jun 2019 15:57
by N3cronium
Don't forget about Neptune's moon Triton! Triton is the only known moon that is tidally locked and has a retrograde motion.

General questions about SpaceEngine

Posted: 03 Jun 2019 16:06
by FastFourierTransform
A-L-E-X wrote:
Source of the post  Gulliver's Travels, the writer made predictions about the Martian moons that turned out to be relatively accurate!

That's an awesome story. I heard that since the time of Galileo it was speculated that Mars had two moons, there was no observation to support the statement but rather a numerologist cabala. Venus has 0 moons, Earth has 1 moon, Mars has x moons and Jupiter had 4 moons. So to fit with a simple sequence they speculated about Mars having 2 moons. As it turn out Jupiter has tens of moons, Saturn has less than Jupiter and the sequence is not so simple and does not obey our any causal relation to a numerical sequence esthetically pleasing or not.

A-L-E-X wrote:
Source of the post I was wondering if it is possible for a moon to move in the reverse direction to its parent planet's rotation

Sure it is. Retrograde satellites. Any moon with an orbital inclination above 90º is considered a retrograde. In the Solar System there are 102 known retrograde moons. The largest retrograde is Triton, in Neptune, with 2700 km in diameter (78% the diameter of our moon). The second largest retrograde moon is Phoebe in Saturn, with 213 km in diameter. All of these moons are believed to be captured objects (they weren't formed from the protosatellite disk but came in a random direction from somewhere else and got trapped by the gravitational pull of the planet).

The most perfect retrograde motion found in the Solar System is for S/2007 S 3, a 5 km moon of Saturn discovered in 2007 and now considered lost (we have been unable to find it again for a decade). If it where traveling in the opposite direction around Saturn it would only be inclined by 3º, so it moves basically against the entire rotation of the planet.

General questions about SpaceEngine

Posted: 03 Jun 2019 16:41
by N3cronium
FastFourierTransform wrote:
A-L-E-X wrote:
Source of the post  Gulliver's Travels, the writer made predictions about the Martian moons that turned out to be relatively accurate!

That's an awesome story. I heard that since the time of Galileo it was speculated that Mars had two moons, there was no observation to support the statement but rather a numerologist cabala. Venus has 0 moons, Earth has 1 moon, Mars has x moons and Jupiter had 4 moons. So to fit with a simple sequence they speculated about Mars having 2 moons. As it turn out Jupiter has tens of moons, Saturn has less than Jupiter and the sequence is not so simple and does not obey our any causal relation to a numerical sequence esthetically pleasing or not.

A-L-E-X wrote:
Source of the post I was wondering if it is possible for a moon to move in the reverse direction to its parent planet's rotation

Sure it is. Retrograde satellites. Any moon with an orbital inclination above 90º is considered a retrograde. In the Solar System there are 102 known retrograde moons. The largest retrograde is Triton, in Neptune, with 2700 km in diameter (78% the diameter of our moon). The second largest retrograde moon is Phoebe in Saturn, with 213 km in diameter. All of these moons are believed to be captured objects (they weren't formed from the protosatellite disk but came in a random direction from somewhere else and got trapped by the gravitational pull of the planet).

The most perfect retrograde motion found in the Solar System is for S/2007 S 3, a 5 km moon of Saturn discovered in 2007 and now considered lost (we have been unable to find it again for a decade). If it where traveling in the opposite direction around Saturn it would only be inclined by 3º, so it moves basically against the entire rotation of the planet.

Just to correct you about S/2007 S 3, it is inclined 177.22° to the ecliptic, not Saturn's equator. The Wikipedia list on the moons of Saturn mentions that the listed inclination values of the retrograde satellites are to the ecliptic while the prograde values are to Saturn's equator.

General questions about SpaceEngine

Posted: 03 Jun 2019 16:47
by FastFourierTransform
N3cronium wrote:
Source of the post Just to correct you about S/2007 S 3, it is inclined 177.22° to the ecliptic, not Saturn's equator. The Wikipedia list on the moons of Saturn mentions that the listed inclination values of the retrograde satellites are to the ecliptic while the prograde values are to Saturn's equator.

Good catch! You are totally right. Well, Saturn has an obliquity of less than 3º so the worst case scenario means that the moon is 6º inclined with respect to Saturn's equator (if it moved in the opposite direction). Maybe there's another satellite closer to the 180º mark then, sorry.

General questions about SpaceEngine

Posted: 03 Jun 2019 16:48
by A-L-E-X
FastFourierTransform wrote:
A-L-E-X wrote:
Source of the post  Gulliver's Travels, the writer made predictions about the Martian moons that turned out to be relatively accurate!

That's an awesome story. I heard that since the time of Galileo it was speculated that Mars had two moons, there was no observation to support the statement but rather a numerologist cabala. Venus has 0 moons, Earth has 1 moon, Mars has x moons and Jupiter had 4 moons. So to fit with a simple sequence they speculated about Mars having 2 moons. As it turn out Jupiter has tens of moons, Saturn has less than Jupiter and the sequence is not so simple and does not obey our any causal relation to a numerical sequence esthetically pleasing or not.

A-L-E-X wrote:
Source of the post I was wondering if it is possible for a moon to move in the reverse direction to its parent planet's rotation

Sure it is. Retrograde satellites. Any moon with an orbital inclination above 90º is considered a retrograde. In the Solar System there are 102 known retrograde moons. The largest retrograde is Triton, in Neptune, with 2700 km in diameter (78% the diameter of our moon). The second largest retrograde moon is Phoebe in Saturn, with 213 km in diameter. All of these moons are believed to be captured objects (they weren't formed from the protosatellite disk but came in a random direction from somewhere else and got trapped by the gravitational pull of the planet).

The most perfect retrograde motion found in the Solar System is for S/2007 S 3, a 5 km moon of Saturn discovered in 2007 and now considered lost (we have been unable to find it again for a decade). If it where traveling in the opposite direction around Saturn it would only be inclined by 3º, so it moves basically against the entire rotation of the planet.

The ironic thing about Gulliver's Travels was that the moons were predicted to be small and the second one (Deimos) of irregular shape.  I remember Bode's Law follows a nice mathematical pattern too to predict where the next planet would be located.
Ah, yes, I just remembered about Triton, that is a rather large satellite to be in retrograde!  I wonder if it came from the Kuiper belt?

General questions about SpaceEngine

Posted: 03 Jun 2019 22:20
by HarbingerDawn
FastFourierTransform wrote:
Source of the post Saturn has an obliquity of less than 3º so the worst case scenario means that the moon is 6º inclined with respect to Saturn's equator

That's Jupiter you're thinking of, Saturn's axial tilt is much greater.

General questions about SpaceEngine

Posted: 04 Jun 2019 03:51
by FastFourierTransform
HarbingerDawn wrote:
Source of the post That's Jupiter you're thinking of, Saturn's axial tilt is much greater.

Again!? Haha sorry guys. That's true. I think I had read the value for the orbital inclination :S

General questions about SpaceEngine

Posted: 06 Jun 2019 12:35
by Muckytuja
Hello! 
Do we have any news about any kind of game play when SE will reach 1.0, or when we buy it on steam will it be only the Planetarium what we pay for?
Thanks! 

General questions about SpaceEngine

Posted: 07 Jun 2019 01:16
by default0.0player
How to roll the camera in "game mode" piloting ships. Rotating camera can be performed by mouse via right mouse button.but only yaw and pitch axis. And you may end up rolling to one side
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How to roll the camera back to level??

General questions about SpaceEngine

Posted: 07 Jun 2019 06:23
by HarbingerDawn
default0.0player wrote:
Source of the post How to roll the camera back to level??

Just press the camera button on the ship toolbar to cycle through the default camera positions.