Meteor Stream

Relatively narrow band of meteoroids stretched out along the orbital path of a comet. It consists of dust released from the nucleus of a comet during its perihelion passage. The dust grains escape the weak gravity of the nucleus and travel on their own independent, heliocentric orbits. Although these orbits remain similar to that of the parent comet, the different velocities at which they were ejected from the nucleus give them slightly different semi-major axes and orbital periods. Slight differences in the resultant orbital periods cause the individual dust grains to spread out along the orbital path of the parent comet. If the Earth’s orbit intersects the meteor stream, a meteor shower is observed. Meteor streams are relatively short-lived phenomena with most only lasting of order 10,000 years. They are dispersed by radiation pressure, collisions between the meteoroids, and gravitational perturbations and collisions with other planets.


Image source: http://astronomy.swin.edu.au/cms/astro/cosmos/M/Meteor+Stream.