Yesterday the annual perseides meteor shower peaked (and I was lucky to see a handful of wakes). Since the bits from Swift-Tuttle have distributed to form a band of debris over the millenia and earth passes through that band, I wonder how to describe the band's dimensions.

I'd go along these lines:

  • "shower period" is from July 17 – August 24, i.e. 39 days
  • Earth orbits the sun at $1.07×10^5$ km per hour says Cornell

I'd assume:

  • Earth moves through the band's full diameter, not e.g. tangentially
  • the band is symmetrical, i.e. the asymmetrical pre and post-maximum rates do not matter

So that gives a simplified $39 × 24 × 1.07×10^5 = 1.00152×10^7$ km as the plausible diameter.

Is my rule of thumb way to calculate this reasonable? As in, campfire discussion precise? Or am I missing relevant details?


1 Answer 1


A lot of it relies on observations, the International Meteor Organization hosts the Visual Meteor Database with observations going back to 1972. So, imagine plotting the Earth's orbit in 3D space over time, and placing a dot every time a meteor was observed. That would essentially give you the view of one little tunnel through the debris stream's path. Over the years, you get more and more tunnels giving you a better idea of what's there and how it's moving.

This is also correlated with known orbiting objects, and usually a known comet can be linked to the debris path. And additional refinements based on the comet's orbit can be made.

As you can imagine, there is an enormous variability in the observation of meteors depending on things like weather, observer's skill, how many people are observing, etc. There are other methods of observation too, like radio scatter, and even radar now. So there are a wide range of different methods employed to bring down the error margin.

The International Meteor Conference for 2020 and 2021 were held online, and the lectures available on Youtube. So you can have a look at those to get an idea for the various methods employed.


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