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It’s a former minimoon. It orbited earth for 2.7 years, making numerous revolutions in that time. There is a cool animation in the article that shows the path i

It’s a former minimoon. It orbited earth for 2.7 years, making numerous revolutions in that time. There is a cool animation in the article that shows the path it took.

ant6n 6y ago
It’s odd they were able to reconstruct its flight path, which appears to be quite chaotic (in the scientific sense), given that the observations are only from after it left the earth-moon System.
- crazygringo 6y ago
  What specifically seems so odd about it? If we know its trajectory with decent precision when it left, and we know the position and gravitational strength of the earth, moon and sun, and you just plug in the numbers and simulate and it should be quite straightforward. I suppose you're referring to "chaotic" meaning that tiny variations or mismeasurements in its later trajectory would be vastly amplified as its orbits were traced. But my understanding is that such chaotic/unpredictable orbital effects generally show up on the scale of many many thousands of orbits if not much more, not 2 years?
  - nsomaru 6y ago
    The first “turn” this object makes is almost at a right angle. Seems entirely unintuitive to me. How does this happen?
    - Delk 6y ago
      It probably passed close to the Moon, and that near pass flung it into the altered trajectory.
      - crazygringo 6y ago
        Exactly. And remember that while the low spatial and temporal resolution of the GIF makes it seem like just being a "pixel" off could result in a totally different orbit (like chaos theory)... ...the actual simulation is dealing with distances of hundreds of thousands of miles, simulated over multiple years of time, presumably with something like minute-by-minute, meter-by-meter precision. (Remember, the object itself is only 1-2 meters large.) The "unintuitive right angle" would appear entirely intuitive if you actually watched it slower while zoomed in closer to the moon.
  - ant6n 6y ago
    It´s counter-intuitive because of the chaotic path. It appears like with every crazy turn this object takes, one would need a couple of extra bits of the initial state - small deviations will result in completely different flight paths. Here, the initial state is of course the final state, but since its reversible that doesn´t really make a difference.

It’s a former minimoon. It orbited earth for 2.7 years, making numerous revolutions in that time. There is a cool animation in the article that shows the path it took.

ant6n 6y ago

It’s odd they were able to reconstruct its flight path, which appears to be quite chaotic (in the scientific sense), given that the observations are only from after it left the earth-moon System.

crazygringo 6y ago
What specifically seems so odd about it? If we know its trajectory with decent precision when it left, and we know the position and gravitational strength of the earth, moon and sun, and you just plug in the numbers and simulate and it should be quite straightforward. I suppose you're referring to "chaotic" meaning that tiny variations or mismeasurements in its later trajectory would be vastly amplified as its orbits were traced. But my understanding is that such chaotic/unpredictable orbital effects generally show up on the scale of many many thousands of orbits if not much more, not 2 years?
- nsomaru 6y ago
  The first “turn” this object makes is almost at a right angle. Seems entirely unintuitive to me. How does this happen?
  - Delk 6y ago
    It probably passed close to the Moon, and that near pass flung it into the altered trajectory.
    - crazygringo 6y ago
      Exactly. And remember that while the low spatial and temporal resolution of the GIF makes it seem like just being a "pixel" off could result in a totally different orbit (like chaos theory)... ...the actual simulation is dealing with distances of hundreds of thousands of miles, simulated over multiple years of time, presumably with something like minute-by-minute, meter-by-meter precision. (Remember, the object itself is only 1-2 meters large.) The "unintuitive right angle" would appear entirely intuitive if you actually watched it slower while zoomed in closer to the moon.
- ant6n 6y ago
  It´s counter-intuitive because of the chaotic path. It appears like with every crazy turn this object takes, one would need a couple of extra bits of the initial state - small deviations will result in completely different flight paths. Here, the initial state is of course the final state, but since its reversible that doesn´t really make a difference.