The Draconids are one of the most notable annual meteor showers, in some
years producing several thousand meteors per hour (like most meteor
showers the number of Draconids varies from year to year). The shower is
expected to peak on Monday 8 October 2018, with best viewing
in the evening (this will b e
the same wherever you are on Earth), visibility should be particularly good this year, with peak meteor activity coming
directly before the New Moon on Tuesday 9 October, so that the meteors will not be obscured by the brightness of the Moon. The Draconids take
their name from the constellation of Draconis, with the meteors
appearing to radiate from the mouth of the Dragon, between the stars
Eltanin and Rastaban. Since this constellation is very high in the
northern sky, the Draconids are an almost exclusively Northern
Hemisphere phenomenon, which sightings from south of the equator being
quite rare.
The radiant point of the Draconid Meteor Shower. Space.com.
The shower is caused by the Earth passing through the trail of the Comet
21P/Giacobini-Zinner, and encountering dust from the tail of this comet
(for this reason the shower is sometimes known as the 'Giacobinid Meteors').
The dust particles strike the atmosphere at speeds of over 200 000 km
per hour, burning up in the upper atmosphere and producing a light show
in the process. The name 21P/Giacobini-Zinner
implies that the comet was the 21st Periodic Comet discovered (a
Periodic Comet has an orbital period of less than 200 years) and that it
was discovered by Michel Giacobini, who first observed the comet from the Nice Observatory in France in 1900, and Ernst Zinner who observed the comet from the Remeis Observatory in Bamberg, Germany, in 1913.
Image of 21P/Giacobini-Zinner, taken on 22 August 2018. Michael Jรคger/Sky & Telescope.
The Earth does not need to pass close to 21P/Giacobini-Zinner for the
meteor shower to occur, it simply passes through a trail of dust from
the comet's tail that is following the same orbital path. Comet 21P/Giacobini-Zinner
itself visits the Inner Solar System once every 6.6 years, last doing
so in 2012, on an eccentric orbit tilted at 31.9° to the plane of the
Solar System, that takes it from 1.03 AU from the Sun (103% of the
average distance at which the Earth orbits the Sun) to 6.00 AU from the
Sun
(6 times as far from the Sun as the Earth,slightly outside the orbit of
Jupiter). The comet last visited the Inner Solar System in this year, reaching about 58 434 00 km (0.39 AU) from Earth on 11 September.
The calculated orbit and position on 7 October 2018 of Comet 21P/Giacobini-Zinner. The Sky Live 3D Solar System Simulator.
See also...
