The Universe: Asteroid Attack

The Universe : ASTEROID ATTACK
History Channel
Season. 5 Episode. 6

http://www.history.com/shows/the-universe
http://en.wikipedia.org/wiki/The_Universe_%28TV_series%29


EXCERPTS:

ASTEROID ATTACK

APOPHIS,
will pass close by 2029,
if it hits the KEYHOLE,
a region in space of one mile wide
then it will hit Earth in 2036.


Apohis was discovered in 2004.
1 in 250,000, possibility to impact on Earth.


Objects that are one km or 2/3 of a mile in diameter or larger,
we think there's about 940 of those, and we've discovered 86% of the population.
If you move to smaller objects,
say 100 meters and larger,
we think there's about 50,000
of those and we've discovered 10%.
And if you move to smaller still objects, 30 meter
and larger-sized objects we think there's about
2 million of those objects and we've discovered much less than 1%.


Now, down here, we've got a basketball-sized rock.
On average, about two of these slam into the Earth's atmosphere
EVERY SINGLE DAY.
Next is the small car-sized object.
This happens about ONCE EVERY TWO WEEKS.
But even something this big is probably gonna burn up completely
before reaching the Earth's surface.

For a typical object hitting the Earth's atmosphere,
it needs to be at least 100 feet in diameter.


But according to recently uncovered fossil records,
the-one-mile-wide Chesapeake bay asteroid
didn't seem to have the same globar effects as the
massive extinctions triggered by the
6-mile asteroid that killed the dinosaurs.


2001, NASA's "NEAR" landed asteroid Eros.
"The NEAR spacecraft even transmitted information back to Earth
for about two weeks while on the surface.
But it has lost its radio link with teh Earth.
and so now, it's simply sitting there, mute for million of years."

"The asteroid explorer Hayabusa, of the
Japan Aerospace Exploration Agency (JAXA)
recently one-upped NEAR.
It's the first spacecraft to ever land on an asteroid
and then return to earth.
It arrived in June 2010 after a four billion mile round trip.


DAWN
DAWN will arrive at 3200-mile-wide Vesta in 2011,
orbit for a year, then reach 600-mile-wide Ceres in 2015.


Asteroids are trackable, because they are close (Near Earth Objects).
Comets come from farther space, and they are not visible until they are 6 months away from Earth. so we have little time to react.


WISE (Wide field Infrared Survey Explorer)
2009 launched
WISE has already found 25,000 asteroids and more than a dozen comets
that were too dark to find using visible light.

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The Universe: Deadly Comets and Meteors

The Universe :DEADLY COMETS AND METEORS
History Channel
Season. 3 Episode. 6

http://www.history.com/shows/the-universe
http://en.wikipedia.org/wiki/The_Universe_%28TV_series%29




EXCERPTS:


Asteroids and Comets
hold secrets of universe
and building blocks of life
and
also enemy.


Asteroids
"Because they were formed at the same times as Earth
asteroids contain the same basic elements
we find on our planet to build things.


Fragments of asteroids
that actually survive an impact
with the Earth's surface
are called METEORITES.


Asteroid Belt - After Mars
Kuiper Belt - After Neptune - Ice and Dust bodies
Oort Cloud - couple of light years from Sun,


"In 1986, the Giotto spacecraft
became the first mission to fly by a comet.
It was Comet Halley.
the only one known to return within our human lifetime.
also visible to the naked eye.


"The so-called carbonaceous chondrite types of asteroids
which are typically found
in the outermost reaches of the main asteroid belt
have an almost exact match
between their deuterium-to-hydrogen ratios and Earth's oceans.


"Jupiter's gravity or light pressure from the Sun
can bump these cosmic relics out of the asteroid belt.
Similarly, the gravity from planet Neptune
can nudge comets out of the Kuiper Belt.


"65 million years ago, a cosmic object
roughly six miles across
impacted the Yucatan Peninsula
near the modern village of Chicxulub, Mexico.
It produced kinetic engergy equivalent to
eight billion Hiroshima atomic bombs.

Many scientists now believe the impact event
extinguished 75% of animal and plant species.

The next Chicxulub-sized impact
is estimated to occur 35 million years from now
but one can never by too certain when it comes to space rocks.


Somwhere on the order of 85 to 95 percent
of the objects that collide with the Earth
come from the main asteroid belt.


Although most potentially hazardous objects are asteroids
comets reamin a legitimate threat.
These icy bodies, which come from the outer solar syatem
can travel three times faster than asteroids.
so it takes only 9 months
for them to get from the orbit of Jupter
to the orbit of Earth.


Fortunately, Jupiter acts as a planetary shield.
It deflects or absorbs comets that drift towards Earth.
And scientists now have the pictures to prove it.
On July 22, 1994, telescopes around the world
caught a glimpse of one of the most violent comet impacts
in the history of humanity.

A String of about 20 comet fragments named Shoemaker-Levy 9
crashed into the upper cloud decks of Jupiter.


On June 30, 1908,
the biggest cosmic disaster in recorded human history
on Earth occurred in Russia.
A large object exploded in Siberia's remote Tunguska wilderness.


smallaer asteroids can create significant damage at the surface.

It's estimated to happen once every 500 years.

Believe it or not,
Earth takes a hit
from soccoer ball-sized space rocks every day.
Most go unseen.
But in 1992, amateur video caught a meteorite.
flash across the nighttime sky.


Congress mandated that NASA must detect
over 90% of near-Earth objects.
over a half-mile in diameter.


APOPHIS, size of city
This space rock will make a close pass
near Earth on April 13, 2029.

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The Universe: End of the Earth

The Universe : END OF THE EARTH
History Channel
Season 1 Episode.3

http://www.history.com/shows/the-universe
http://en.wikipedia.org/wiki/The_Universe_%28TV_series%29
http://www.youtube.com/watch?v=s4ss0j0aknM


EXCERPTS:

- DEEP THREATS TO OUR PLANET


APOPHIS, which got too close for comfort in 2004.


Tunguska Explosion @ Siberia

June 30th 1908, 7:15 am
An object, half the size of a football field,
plunged down from space at around 34,000 miles per hour.
violently exploded about Siberia's Tunguska forest.
It became the largest explosion on Earth in modern human history.
The blast sparked heatwaves which torched 80 million trees, area of the size of Rhodes island.

If that asteroid hit just few hours later,
it would not have hit Siberia,
it would have hit over Europe.
... million people would die like that. (clicking fingers)
...
The blast over Siberia released energy equivalent to 15 megatons of TNT,
a thousand times greater than Hiroshima.


Scientists call these trespassers Near Earth Objects, or NEOs.
They're asteroids and comets, which are leftovers from the formation of the planets.


Comets move in the Oort Cloud in the Kuiper Belt,
which is beyond the planet Neptune.

Asteroids travel in a band
between Jupiter and Mars.


[65 million years ago, an asteroid - size of small city, hit Yucatan Peninsula, present day Mexican village Chicxulub, and caused the extinction of dinosaurs and growth of mammals.]


In 1998 Congress urged NASA to detect all the Near Earth Objects over a half mile in diameter or more.
They found: Over 850 NEOs in our vicinity.

NASA's Space-guard Survey has detected over 90% of all NEOs deemed harmful.


... so Congress now asks NASA to locate all NEOs 500 feet in diameter.


It's hard to believe the Earth has survived over 4.5 billion years.


Apophis, is scheduled to pass dangerously close to our planet again,
on Friday, the 13th in April 2029.

Apophis has an over 99% chance of missing the Earth in 2029.
but if Apophis passes the Earth at a distance of exactly 18,893 miles,
it may pass through a GRAVITATIONAL KEYHOLE,
- a narrow region in space, a half mile wide -
if this happens, the Earth's gravity could upset Apophis,
and change its trajectory.
It could cause it to return, and hit Earth seven years later,
on April 13th 2036.

At the present time, Apophis has 1 in 45,000 chance of delivering a deadly blow in 2036.
But even these odds have scientists placing bets.

Apophis could impact any point along this "path of risk".
It begins in Western Siberia, cuts across and down the Pacific Ocean, near California,
then it traverses Central America and finished in Western Africa.


GAMMA-RAYS BURST

The potent radiation cooks the upper atmosphere,
Our ozone layer roasts,
Across the hemisphere, human beings burn to death from radiation a hundreds times the fatal dose.
The disappearing ozone layer causes increased temperatures around the world,
triggering cyclones, tsunamis and hurricanes.
Most life on the surfaces of land and water incinerates.
it could happen if a gamma-ray burst hit Earth from 100 light years away.


The gamma-ray burst is equivalent to
the brightness of million trillion suns.


For every 300 gamma-ray bursts that go off
only one is pointed in our direction,
and wo we only see 1 of those 300.


Even if a gamma-ray burst were to occur
not 100 but 1000 light years away,
the Earth could still face apocalyptic destruction.


Statistically this ghastly scenario has 1% chance
of happening once in the Earth's entire lifetime.
But even these odds aren't reassuring
if you're living on the planet at that very moment.

Gamma-Rays: They travel at the speed of light. 186,000 miles per second.



SUN

For over 4 billion years the Sun has been an ally,
warming and feeding our planet.
But in time our solar heater will become our enemy.


BIG RIP

Edwin Hubble first discovered that Universe is expanding back in the 1920s.
But it was not unitil 1998
when a crack team of scientists measured that this expansion
is moving like a runaway train.


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