The shower is active
each year from around 17 July to 24 August, although for most of that period
only a few meteors an hour will be visible. From the UK, the peak of the shower
occurs in the late evening on 12 August to the morning of 13 August, when as many
as 100 meteors or more may be seen each hour. This year, for the first time
since 2007, this peak coincides with a new moon on 14 August, creating ideal
dark sky conditions for meteor-spotting.
Meteors
(popularly known as 'shooting stars') are the result of small particles, some
as small as a grain of sand, entering Earth's atmosphere at high speed. The
tail of the Comet Swift-Tuttle, which last passed near Earth in 1992, leaves
such debris in Earth's path. On entering the atmosphere, these particles heat
the air around them, causing the characteristic streak of light seen from the
ground. This shower of meteors appears to originate from a single point, called
a 'radiant', in the constellation of Perseus, hence the name.
Unlike many celestial events meteor showers are straightforward
to watch, and for most people the best equipment to use is simply the naked
eye. Advice from experienced meteor observers is to wrap up well and set up a
reclining chair to allow you to look up at the sky in comfort. If possible it
also helps to be in a dark place away from artificial light, and to have an
unobstructed view of the sky.
Although the number of visible meteors is hard to predict
accurately, at least one every few minutes can be expected. They mostly appear
as fleeting streaks of light lasting less than a second, but the brightest ones
leave behind trails of vaporised gases and glowing air molecules that may take
a few seconds to fade.
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