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How can it be called a 'capture' when it's already known when and how it will leave. That's like calling a resort vacation stay a kidnapping.
by RandomCitizen12 2y ago
How can it be called a 'capture' when it's already known when and how it will leave. That's like calling a resort vacation stay a kidnapping.
- pengaru 2y agoTechnically The Moon is slowly leaving earth's orbit too, to the tune of 38mm per year[0]. Everything's temporary... [0] https://en.wikipedia.org/wiki/Orbit_of_the_Moon https://en.wikipedia.org/wiki/Orbit_of_the_Moon
- deafpolygon 2y agoAny impact on tidal activity?
- nso 2y agoLike measurable in our lifetime? The average distance to the moon will be 3.8 meters further away in a hundred years. That's insignificant as far as tides goes. Despite what another commenter says, the moon will not leave earths captive field. It will recede until it gets tidally locked with earth, and both the tide cycles and the moons recension will halt. That is, if there still is water in a few billion years and it hasn't been replaced with Brawndo
- flqn 2y agoIs the moon not already tidally locked? The same hemisphere of it always faces the earth. Is there a different kind of tidal locking or orbital resonance it will settle into?
- alfiopuglisi 2y agoIt goes on until an Earth's day is as long as a month. Both will face each other in a fixed way. But it takes many billions of years and the Sun will burn both to a cinder much before that.
- mjevans 2y agoThat's like calling a lifetime lived within just one village 'temporary'. On the scale of human events it's nearly as permanent as anything else for which we commonly ascribe permanence and reliability within lifetime scales.
- runako 2y agoIt's fair to describe objects in relation to the lifespans of those objects, not of those who observe. "On the scale of human events" is not the only relevant timeframe for discussing celestial bodies.
- ck2 2y agothe way I remember that fact is it is also average fingernail growth per year
- jumploops 2y agoGoodbye Moon would be a great name for a children’s book focused on space and time!
- bongodongobob 2y agoBecause during that time from its frame of reference it will be falling around the earth until it reaches escape velocity and starts falling around the sun again.
- enragedcacti 2y agoI had the same confusion so here's my layman's understanding. They are defining capture/orbit as having negative "geocentric energy" which is a term of art no one else seems to use but I think is just a mathematical representation of the following: > a temporary satellite is any body that enters the Hill sphere of a planet at a sufficiently low velocity such that it becomes gravitationally bound to the planet for some period of time. [1] again stretching my understanding too far, I think this basically means that in the absence of other celestial bodies the satellite would be in a stable orbit, but that in reality after some time it gets far enough away that the sun's gravitational pull dominates and stops it from making a full orbit. [1] https://en.wikipedia.org/wiki/Temporary_satellite https://en.wikipedia.org/wiki/Temporary_satellite
- timjver 2y ago> in the absence of other celestial bodies the satellite would be in a stable orbit Presumably entering such an orbit is only possible due to forces from other celestial bodies in the first place, since otherwise if you reversed time it would spontaneously leave its orbit. In other words, the act of the earth "capturing" the object is ultimately performed by external forces?
- hansvm 2y agoTo be fair, it's still kidnapping in most states even if the duration is very short.