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After reading the Astronomy Magazine article Perseid meteor shower set for its best show in nearly 20 years and NASA's Look Up! Perseid Meteor Shower Peaks Aug. 11-12, I understand that Jupiter's gravity is affecting this year's possible peak rate of Perseid's meteors.

I think it is - in simple terms - deflecting some of them out of their general orbit, a bit more towards earth, so that we intercept more than usual. But I am having difficulty visualizing this. Is this deflection in the plane of the ecliptic, or out of plane? At our closest approach, how far away are we from the orbit of this dust?

A good diagram would really help! I found this at space.com credited to Jeremie Vaubaillon, but it's not helping me with the 'big picture'.

enter image description here

Also found this here and credited to NASA/JPL:

enter image description here

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    $\begingroup$ Similar dot plots in publications by Vaubaillon et al. are titled Nodes, with axes labeled X (au, ecl.) and Y (au, ecl.). They show where simulated meteoroids cross the plane of Earth's orbit. $\endgroup$ – Mike G Aug 10 '16 at 13:06
  • $\begingroup$ @MikeG Thanks for that! So do you know if the 'clumping' just a statistical artifact of a finite number of test particles, or does it represent some kind of dynamical evolution over a long period of time? $\endgroup$ – uhoh Aug 10 '16 at 13:20
  • $\begingroup$ I think the clumps are supposed to be ejected during different perihelia of the comet, e.g. 1737 or 1862, and have different histories of interactions with planets. $\endgroup$ – Mike G Aug 10 '16 at 13:43
  • $\begingroup$ @MikeG that's really beautiful then! Wish I could see the whole thing evolve. I'll try to stop by the library and read more and maybe follow up. Thanks!! $\endgroup$ – uhoh Aug 10 '16 at 14:30
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To put it in simple terms, a comet's debris trail or dust trail is like a ring of debris that generally follows the entire orbit of the comet, more concentrated close to the comet, more spread out further away, but it can be thought of, for simplicity, as an entire ring of debris, kind of, a miniature asteroid belt with a fixed elliptical path. The picture below isn't perfect, cause it gives the impression that orbits are all the same when there's some spreading out, but it's the gist of it. (Note, the debris field and comet in the picture below isn't Swift-Tuttle/Perseid)

https://www.astro.umd.edu/~msk/science/trails/encke-trail.png

The reason for this is that any debris that's knocked off the comet at a low velocity has pretty much the same orbit as the original comet, and over hundreds or thousands of orbits, it tends to fill up the entire comet's orbit with mostly tiny particles, some larger ones. The debris field or dust trail from the comet generally follows in the comets orbit.

This picture is a bit more accurate as to what the Earth is passing through.

https://lintvwpri.files.wordpress.com/2016/08/perseid_base4.png?w=650&h=366

The more compact the dust trail or debris field, the more meteors, but the smaller the target the Earth has to hit, so odds are greater that the Earth will miss the field entirely. The more spread out, the greater chance the Earth hits the debris field, but more spread out means we get fewer meteors.

Earth's orbit crosses the Perseid (eliptical ring of debris) or Swift-Tuttle's debris field about the same time every year because Earth's and Swift-Tuttle's orbits nearly intersect.

http://www.amsmeteors.org/wp-content/uploads/2015/08/comet-path.png

This year, because of the placement of Jupiter, the debris field (which we can kind of think of as a ring), got bent by Jupiter, and Earth is hitting closer to the center of the debris field which means, more meteors. I can't say on which plane the field got bent, cause it depends on it's orbital relation to Jupiter and I couldn't find that, but it was the ring of debris that got bent, so Earth will hit it more directly this year than usual.

Because the ring of debris is pretty much permanent, Jupiter bends the ring every 11 years as it passes closest to it, and occasionally that bend works in earths' favor and gives us more meteors, so its a rare event that might not happen again for 11 years, it might be over 100 years before Jupiter does this for us again.

See article.

Typically Earth just grazes by Swift-Tuttle’s debris field, but our planet will be even closer to the particle stream this year thanks to some help from our neighbor Jupiter. The gas giant occasionally gets close to the comet stream, and its immense gravity pushes the debris nearer to Earth.

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  • $\begingroup$ Wow this is an incredibly well-written and thought-out explanation! Thanks for taking the time to exain a number of important points simply and clearly! $\endgroup$ – uhoh Aug 10 '16 at 5:23
  • $\begingroup$ (someone should tell The Verge that 60 to 80 "comets per hour" is a little on the high side :-) $\endgroup$ – uhoh Aug 10 '16 at 5:26
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    $\begingroup$ Great answer. I had a small question that answered itself while I wrote it. Maybe someone is wondering the same, so here goes: If Jupiter only pushes the debris field every 11 years, shouldn't it remain more in Earth's path for the time being, and we pass through the centre of it until the next push? Answer: As you wrote, the debris stream is moving along the path of the comet, so the part of it that gets pushed our way by Jupiter has moved on by the time Earth comes through again. $\endgroup$ – Alex Aug 10 '16 at 8:24

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