![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
prettygoodwordevection (ih-VEK-shuhn) - n., a perturbation of the moon's motion in its orbit due to the attraction of the sun.
If the earth and moon were all by their lonesome in space, without a sun, the moon's orbit would be a perfect ellipse. With the sun, the moon's pulled off that ellipse in a direction that changes throughout the year that's the earth's orbit around the sun -- so it has a wobble, or libration, of about 1.274°. This was known in ancient times (and its discovery attributed to Ptolemy). The current name was given by 16th century astronomer Ismaël Boulliau, in a treatise that expanded on (and attempted to explain) Kepler's elliptical theories, from the Latin ēvectiōn, a going up, from ēvectus, the past participle of ēvehere, to raise up, relating it to his hypothesis of conic sections and orbits.
---L.
If the earth and moon were all by their lonesome in space, without a sun, the moon's orbit would be a perfect ellipse. With the sun, the moon's pulled off that ellipse in a direction that changes throughout the year that's the earth's orbit around the sun -- so it has a wobble, or libration, of about 1.274°. This was known in ancient times (and its discovery attributed to Ptolemy). The current name was given by 16th century astronomer Ismaël Boulliau, in a treatise that expanded on (and attempted to explain) Kepler's elliptical theories, from the Latin ēvectiōn, a going up, from ēvectus, the past participle of ēvehere, to raise up, relating it to his hypothesis of conic sections and orbits.
---L.
*
Date: 2021-04-06 04:14 pm (UTC)(or at least a poly relationships story title)
Re: *
Date: 2021-04-06 04:16 pm (UTC)Re: *
Date: 2021-04-06 05:14 pm (UTC)The one I was specifically thinking of (because it fits the fandom I'm currently in) is person A, involved with person B, starting relationship with person C, and how the A/C relationship introduces perturbations in the A/B relationship.
tucks the plotbunny into my hutch and feeds it
Re: *
Date: 2021-04-06 05:32 pm (UTC)