whoa watch your head
some seriously big asteroids are
crashing into earth
what kind of shapes and sizes do they
have
which ones would have the deadliest
impact
and
which one would be most likely to hit us
uh oh get your bunker ready
this is what if and here's what would
happen if the largest asteroid hit earth
okay let's get the terminology out of
the way i say asteroids but some of the
objects on our list are not asteroids
they're comets both asteroids and comets
are objects in our solar system but they
aren't the same
asteroids are rocky leftovers from the
early formation of our planetary
neighborhood
and of the over 1 million that we know
of
most orbit the sun
in the asteroid belt between mars and
jupiter
on the other hand comets are snowballs
made of frozen gases rock and dust
they orbit the sun and when they get too
close they start to melt
this releases a giant cloud of dust and
gas that can be larger than most planets
with 3 000 known comets in the solar
system
could a few be ready to turn the earth
into a giant cloud of dust too
[Music]
chelyabinsk meteorite
let's start with a smaller object that
has already hit our planet
meet the chelyabinsk meteorite it
exploded over russia in february of 2013
with a diameter of about 17 meters it
was relatively small but the impact was
huge
the explosion had the energetic
equivalent of 500 000 tons of tnt
that's about 30 times as powerful
as the bomb that was dropped on
hiroshima
it injured 1200 people and caused
enormous property damage
pretty big effects from a little
extraterrestrial visitor
chickslub
moving on to something bigger we'll go
65 million years into the past
the massive chick's lube asteroid was
likely one of the forces that resulted
in the mass extinction of the dinosaurs
it was about 10 to 15 kilometers wide
and its impact crater in mexico's
yucatan peninsula measures
180 kilometers wide
and 900 meters deep
whoa
when this asteroid slammed into earth it
devastated everything nearby
the blast wave sent enormous amounts of
rocky material into the atmosphere and
it caused tsunamis as high as 1500
meters
while all the soot didn't completely
block out the sun
it reduced the amount of sunlight
reaching the surface of our planet
that seriously devastated plant growth
and had rippling consequences on the
food chain
eventually it caused entire ecosystems
to collapse
of all the objects that could collide
with us
has one of the more interesting shapes
this rocky cigar-shaped object is about
400 meters in length
nasa classifies it as a comet but it
exhibits traits of an asteroid too
and it doesn't have an attachment to any
star system so we don't know where in
space it originates from
in 2017 it passed by the earth at a
distance of 41 million kilometers
now while we were safe from impact on
that occasion it could have resulted in
a lot of destruction
if this interstellar guest crashed into
earth darkness would cover our planet
and if the dust and debris stayed in our
atmosphere for a long time it would kill
many plants animals and humans that
depend on the sun
bennu bennu is not only an asteroid you
should worry about
it's the asteroid you should worry about
it has a 1 in 1700 chance of colliding
with earth in september of the year 2182
at only half a kilometer wide it's
relatively small but remember how
significant the chelyabinsk impact was
yeah with that in mind
you might be a little nervous when it
makes a close approach to earth every 6
years
[Music]
shoemaker levy 9
this next comet doesn't have any chance
of hitting earth
that's because it already collided with
jupiter in 1994
but you could imagine the destruction
this one and a half to two kilometer
wide comet would have caused on our home
turf
it broke into 20 pieces as a result of
jupiter's gravity
the collisions from these fragments were
so powerful that they were similar to
the detonations of about 300 million
atomic bombs
plumes of debris shot as high as 2 000
to 3 000 kilometers
and the atmosphere heated to scorching
temperatures of 30 000 to 40 000 degrees
you must be pretty relieved that
shoemaker levy 9 never hit us
series
last but far from the least is an
asteroid so big it's technically
classified as a dwarf planet
ceres is the largest object in the
asteroid belt it makes up 25
of the belt's total mass
the radius of series is 476
kilometers
that makes it over 60 times larger than
our ancient friend chickslub
if ceres collided with earth
there wouldn't just be devastation
there would be no earth
the size of ceres alone would block out
the sun as it approached
and then
the impact would remove 10 kilometers of
the earth's crust
hypersonic shock waves would ripple
across the globe
everything in its path would be
incinerated and leveled
nothing would stand a chance of
surviving
our planet would essentially turn into a
glowing ball of fire and melted rock
if by some miracle or secret underground
bunker you survived
well you wouldn't last long
soot in the atmosphere would result in
something like a nuclear winter
maybe you should get used to your life
underground
but
that's a story
for another
what if
[Music]