[RandomCitizen12]

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.

[enragedcacti]

I 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

[timjver]

> 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?

[pengaru]

Technically 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

[mjevans]

That'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.

[jumploops]

Goodbye Moon would be a great name for a children’s book focused on space and time!

[deafpolygon]

Any impact on tidal activity?

[ck2]

the way I remember that fact is it is also average fingernail growth per year

[bongodongobob]

Because 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.

[hansvm]

To be fair, it's still kidnapping in most states even if the duration is very short.