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BenGun said:
Thanks Publius,
nice animation but is this real? I noticed that the object (named Joo23) in the animation did not come from Earth but from outer space. Now, I won't claim that this is an UFO, but it be interesting to learn why the object zig-zagged around whereas moon remained on its way.
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mike alexander answers the question. The animation distorts the scale of the objects to each other. Object J0023 is
tiny compared to the Earth and Moon. Note that the Moon dot actually appears larger than the Earth dot - not very scale accurate there, either.
If you're standing on a bathroom scale and a fly lands on you, you will not register a blip on the scale.
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JayUtah said:
I'm not sure the moon was of major influence to the orbits seen in that animation. Didn't it slingshot back out of earth orbit due to the orientation of the final ellipse?
I don't believe so. The object was in a somewhat metastable orbit around Earth, albeit highly precessional. It seemed indeed to be shallowing, and that was probably due to solar perturbance. I doubt such an orbit would have become any more stable, nor remained Earth-centered for more than a month. But things really happened when it made the close pass at the Moon, so my money's on its having been tossed out of Earth orbit by the Moon.
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It is difficult to perceive differences in motion caused purely by the Moon rather than by the Earth/Moon pair. I try looking for changes in speed or direction specifically when the Moon is closer compared to the Earth. Anything that upsets the smooth curve motion of a regular ellipse.
To my eye, the first ellipse is very egg-shaped and smooth, with the highest loop (I forget apogee and perigee). The second ellipse is a bit fatter and lower, the third is higher again almost matching the first ellipse. The third is also lopsided. The fourth is lower, the fifth still lower, and the sixth even lower. At the end of the sixth ellipse, the object approaches the Moon in it's path, and it turns and passes between the Earth and Moon and ejects from the system. To my eye, the speed is also enhanced by that approach, though that could be a trick because of the inherent Kepler Law speed increase on close approach to the Earth/Moon. However, the curve change seems significant to me. To my eye, the reason the object ejects is because of the momentum slingshot from close chase of the Moon. Otherwise, I would expect the pattern of precessing declining ellipses to have continued. IANA Orbital Mechanic -YMMV.