Explaining Meteor Shower Radiants [VIDEO UPDATE]

I made a video today to use in my Astro 3105 course, "Physics, Chemistry, and Geology of the Solar System."  There's no narration because I plan to explain it myself in-class, but I'll give a quick explanation in the text below.  The goal is to explain the dates and radiants of a few of the big meteor showers.

We begin by looking at the orbits of Halley's Comet and the Earth.  Although the orbits don't intersect directly due to the comet's orbital inclination, the closest approach between the two paths occurs in early May every year.  Now picture the Earth moving along the green orbit circle counterclockwise, the direction indicated by the arrows.  And visualize a long elliptical ribbon of comet-chunks left behind like breadcrumbs all along the comet's orbit, each chunk moving along the orbit clockwise (again according to the arrows).  This is a nearly head-on collision, so the chunks would appear to be coming at us from the bottom of the image...  And as we change perspective we see that they will appear to come from the constellation Aquarius.  We've just discovered the Eta Aquariids meteor shower, which peaks in early May.

Now we move to the other close-approach point between the two orbits, in late October.  This is again a near-head-on collision, and the meteors would appear to come at us from the upper-right.  Changing perspective, we see that this points to the Orionids shower in late October.

Now we switch to a different comet, 55P/Tempel-Tuttle, whose orbit appears nearly tangent to but slightly inclined to Earth's orbit.  Actually, the inclination is nearly 180 degrees; in other words, the comet and its debris-ribbon again move clockwise around the orbit, whereas the Earth moves counterclockwise.  The meteors should appear to come from directly in front of the Earth - which in mid-November points to radiant of the Leonids shower.

And finally, we switch to the numbered asteroid (3200) Phaethon, which orbits counterclockwise like any respectable asteroid should.  But we are discussing Phaethon because it's not a respectable asteroid - it must be some sort of dead comet or "rock comet" that has spread debris all along its orbit like a comet would.  Now since the Earth is moving mostly "upward" and the debris is moving mostly "leftward," we would expect the meteors to seem to come from the upper-right. And when we change perspective, we see the radiant of the Geminid meteor shower of mid-December.

I've always had a hard time visualizing how debris left behind by a comet could appear to hit the Earth's atmosphere from the same direction at the same time of the year, year after year.  Hopefully this animation has helped you as much as it's helped me.