Meteors and Meteorites Video Lecture - Class 8

you're out camping late one night in
hopes of seeing a shooting star suddenly
you see one you wish that your special
someone will fall in love with you but
when you wish upon a star what are you
actually wishing upon what is a shooting
star
this is our solar system because the
sun's gravity is so strong nearly
everything is settled into similar
orbits we call this the orbital plane
most maps of the solar system just show
the planets but there are a lot of
objects flying around this space this is
the asteroid belt roughly between Mars
and Jupiter beyond Neptune is the Kuiper
belt and out here is the Oort cloud
there are also lots of stuff that
doesn't fit neatly into any of these
categories the smaller you get the more
of it there is all of these space
objects are flying around and sometimes
colliding with earth when these object
hit Earth they burn up in the atmosphere
creating brilliant streaks of light this
is what causes of shooting stars however
did you know that most shooting stars
are not spaceships size rocks hitting us
atmosphere most shooting stars are
actually just a little specks of dust
and most the dust comes from comets
comets come from those distant reaches
of our solar system where the sun's
gravity barely hangs on this lovely
location is called the Oort cloud
scientists have never actually seen the
Oort cloud because it's light years away
and very dark but based off the unique
orbits of comets they hypothesize that
there must be a massive cloud of icy and
rocky material with millions of comets
surrounding our solar system in a giant
sphere because comets that do make it
into our solar system come from so far
away they orbit our Sun differently than
any other body in the solar system
rather than stay on the same orbital
plane as most of the planets and
everything else comet's orbit in tightly
ellipses tilted at amazing variations
from the orbital plane orbital shapes
are described in terms of eccentricity
an almost perfect circular orbit like
Venus follows has an eccentricity of
almost zero on the other hand of the
spectrum the famous comet hale-bopp
which passed the earth in 1997 has an
eccentricity of nearly one which is
about as eccentric as you can get
without getting flung out of the solar
system forever
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because they have such an eccentric
orbits and come from so far away some
comets take hundreds to millions of
years to orbit the Sun for example we
won't be seeing Hale Bopp again until
the year 4380 up close a comet is just a
pile of extremely dark dusty rocks held
together by frozen gases in water as a
comet's orbit takes it closer the Sun it
transforms into something far more
beautiful the Sun warms the frozen ice
of the comet the heat causes the ice to
melt or rather sublimate this means the
ice skips the liquid phase and go
straight from solid into gas the
increasing pressure from the expanding
gas trapped in the comet creates mini
explosions on the surface these mini
explosions release gas all the chunks of
rock ice and space dust the gas forms a
cloud that surrounds the comet called a
coma
and as this gas and dust gets pushed
farther away from the comet by solar
winds it forms a long beautiful tail
that can extend for millions of miles
away from the Sun the light we see isn't
emitted from the comet rather we see the
light of the Sun reflected and all that
gas dust and ice the larger particles
ejected from the comet continue in
roughly the same orbit this is called
the dust trail or meteoroids stream
after making multiple passes into the
Sun completing the same orbit again and
again and again the comment has ejected
enough space dust to form a complete
meteoroids stream this debris fills the
orbit of the comet
imagine if someone paces around your
kitchen table eating cookies following
the same calf each time eventually there
will be a complete ring of cookie crumbs
left behind this is essentially what a
meteoroid stream is a giant ring of
spaced crumb debris or future shooting
stars each year when Earth passes
through this meteoroid stream we
intercept all the specks of dust and
rock left behind and a meteor shower is
the result so even hundreds of years
after a comet has passed through our
solar system the earth can continue to
enjoy a meteor shower every year around
the same time when we pass through the
Comets old orbit so next time you
witness a meteor shower tell your
friends it's more like a dust shower
thank you so much for watching subscribe
for our next video to learn about much
bigger objects that hit our planet and
how likely they are to hit you larger
objects from their sources can also
cause shooting stars sometimes they
explode and it's pretty awesome see you
next time
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