As Earth revolves around the Sun, it regularly comes across static clouds
of small particles left in the wake of ancient comets. Indeed, as it
approaches the Sun wonderful tails will be stripped from a comet by stellar
winds. Though too diffuse to reflect sunlight, the cloud of particles left
behind continues to orbit around the Sun and crosses the path of some
planets. Here the Leonid shower has caused this bright "shooting star":
actually a very tiny grain of dust burning in the Earth's atmosphere due to
the high speed of impact.