We see a shower when Earth, in its annual travels around the Sun, passes through a meteoroid stream
strung along a comet's orbit.
Consequently, after a comet has returned many times to perihelion, the meteoroid stream
will consists of a large number of separate individual dust trails.
Meteor Shower--A regular (typically annual) event in which the orbit of Earth intersects that of a meteoroid stream
, causing a number of meteors with approximately parallel trajectories appearing to emanate from the same radiant.
EST, when Earth intercepted a meteoroid stream
that astronomers believe the comet ejected in 1767.
Every year as the Earth circles the Sun we pass through the Leonid meteoroid stream
around November 17th.
FOR SEVERAL DAYS around October 21st every year, Earth passes through the Orionid meteoroid stream
: sparse, widely scattered bits of Halley's Comet.
The title of the study describes the new branch of the Taurid meteoroid stream
as a "real source of potentially hazardous bodies."
Such events, known as meteor showers, are common; our planet travels through about 12 a year, each from a meteoroid stream
spewed by a different comet.
But because the comet--and the meteoroid stream
all along its orbit--have made hundreds of trips around the Sun over tens of thousands of years, slight periodic perturbations can add up.
A Leonid storm occurs once every 33 years, when Earth passes through the meteoroid stream
shortly after Temple-Tuttle has neared the sun and spewed fresh particles.
Complicating things, mass sorting in the meteoroid stream
means that faint meteors are their most abundant before the visual peak, and bright ones after.
The Geminid meteoroid stream
has been somewhat sorted by mass.