Monday 12 August 2019

The Perseid Meteor Shower.

The Perseid Meteor shower lasts from late July to early September each year, and are expected to be at a peak on Tuesday 13 August 2019. Since the Moon is currently more than half full and still waxing (becoming more full), viewing will not be perfect for the Perseids this year. The Perseids get their name from the constellation of Perseus, in which the meteors have their radiant (the point from which they appear to originate).
The radiant of the Perseid Meteors. Sky & Telescope Magazine.
The shower is caused by the Earth passing through the trail of the Comet 109P/Swift-Tuttle, and encountering dust from the tail of this comet. 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 orbit and current position of Comet 109P/Swift-Tuttle. The Sky Live 3D Solar System Simulator.

109P/Swift-Tuttle is currently 38.6 AU from the Sun (i.e. 38.6 times as far from the Sun as Earth and some way outside the orbit of Neptune) and 39.4 AU from the Earth. The comet is next expected to visit the Inner Solar System in 2126, reaching about 22 950 00 km  (0.15 AU) from Earth in August of that year.
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