Witnesses across much of northwest Europe have reported observing a
bright fireball at about 8.15 pm local time GMT on Sunday 20 December 2020. The fireball is described as
having moved from northwest to southeast, with some witnesses in England and the Netherlands reporting an audible boom which accompanied the meteor. A fireball is defined
as a meteor
(shooting star) brighter than the
planet Venus. These are typically caused by pieces of rock burning up in
the atmosphere, but can be the result of man-made space-junk burning up
on re-entry.
Fireball meteor (top left of image) seen from De Weere in the Netherlands on 20 December 2020. Frank Breedijk/American Meteor Society. The fireball was seen from Belgium, the Netherlands,
England, Scotland, and Germany,has been calculated to
move from northwest to southeast the Southern North Sea, dissapearing about 30 km off the coast of the Netherlands.
Heat map of northwest Europe
showing areas where sightings of the meteor were reported (warmer colours indicate more sightings), and the
apparent path of the object (blue arrow). American Meteor Society.
Objects
of this size probably enter the Earth's atmosphere several times a
year, though unless they do so over populated areas they are unlikely to
be noticed. They are officially described as fireballs if they produce a
light brighter than the planet Venus. The brightness of a meteor is caused by friction with
the Earth's atmosphere, which is typically far greater than that caused
by simple falling, due to the initial trajectory of the object. Such
objects typically eventually explode in an airburst called by the
friction, causing them to vanish as an luminous object. However this is
not the end of the story as such explosions result in the production of a
number of smaller objects, which fall to the ground under the influence
of gravity (which does not cause the luminescence associated with
friction-induced heating).
These 'dark objects' do not continue along the path
of the original bolide, but neither do they fall directly to the ground,
but rather follow a course determined by the atmospheric currents
(winds) through which the objects pass. Scientists are able to calculate potential trajectories for hypothetical dark
objects derived from meteors using data from weather monitoring services.
See also...
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