Meteori se u atmosferi Zemlje mogu kretati brzinom i do 72 km/s. Ne ispod 11 km/s. Ne znam koji PVO sistem bi na to reagovao. Ovo je početna brzina, jer uspori zbog otpora atmosfere, ali opet ...
Citiraj:
There are three factors which combine to create a meteor's starting speed
in the atmosphere. The minimum speed is around 11 kilometers per
second...this is due solely to the earth's gravity. A particle that has a
speed of zero relative to the earth, will be drawn in by gravity until it
is traveling just over 11kps when it reaches meteor height (~100km). The
second factor is the particle's motion around the sun, and can range up to
42 kps at the earth's orbital distance. Anything moving faster is not in
orbit around the sun, and is either passing through the solar system or has
been accelerated by interaction with a solar system object and is on it's
way out. These are VERY rare. Meteor shower particles must be in orbit,
since we pass them as our orbits intersect each year. Finally there is the
earth's motion around the sun..we are moving around 30 kps in our own
orbit, so we are adding our own motion to that of the particle around the
sun. So showers with slow speeds (< 30 kps) are catching up to us from
behind. Meanwhile, the fastest showers, such as the leonids, are moving at
high speed in a retrograde orbit (opposite that of the earth) and smash
into our windshield (the atmosphere) at the highest speed. (~72 kps). (BTW,
the theoretical fastest speed is not 72+30+11 kps, rather it is about 72.9
kps...the speeds are not added directly....it is the square root of the sum
of the squares....to explain it simply, a particle moving 72 kps has less
time to be accelerated and only reaches 73, whil a particle whose speed is
zero has lots of time to be accelrated by gravity so winds up at 11 kps)
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