The comet that gives rise to the Perseid meteor shower, Comet Swift-Tuttle, was photographed during its last pass into the inner Solar System in 1992. Image credit: NASA, of Comet Swift-Tuttle.

The most dangerous object known to humanity

If you gazed up at the Perseids, you’ll want to appreciate the fact that we’re still here.

“Honestly, if you’re given the choice between Armageddon or tea, you don’t say ‘what kind of tea?” -Neil Gaiman

Every August, the Perseid meteor shower delights skywatchers everywhere. While some years it’s a disappointment, either being washed out by a bright Moon or delivering a relatively sparse stream of particles for Earth to collide with, other years the show is spectacular. This year, in particular, a minor but significant enhancement is occurring: the orbit of Jupiter gravitationally influenced the stream of particles we’re colliding with, causing the center of the stream to collide with Earth (rather than the outskirts). Although many of us will enjoy the 50%-or-so enhancement in the rate of meteors, it brings up an uncomfortable reality: it’s possible that one day Jupiter will gravitationally influence the comet that gives rise to this meteor shower, and cause it to collide with Earth.

A timelapse of 2015′s Perseid meteor shower, with 27 separate images containing 29 meteors merged together. Image credit: Trevor Bexon, under cc-by-2.0, via https://www.flickr.com/photos/trevorbexon/20543624326.

First, the good news: the motions of planets and comets are very well calculable, and this particular comet —…