History Channel
Season. 3 Episode. 12 (final)
http://www.history.com/shows/the-universe
http://en.wikipedia.org/wiki/The_Universe_%28TV_series%29
EXCERPTS:
AURORA BOREALIS
"It was named after Aurora,
the Roman goddess of dawn,
and the Greek god of the north wind, Boreas.
Auroras, by themselves pose no threat to humans
But the incrased solar activity associated with them
can generate about one millin megawatts of electricity
and cause us problems in other ways.
Sun has an atmosphere that extends well beyond the Earth
So the Earth is actually living in the outer atmosphere of the Sun.
So the Sun has a 22-year cycle of activity.
Every 11 years it becomes more active
and then it reverses its polarity and comes back.
and the auroras are one of the best markers of that.
SHOOTING STAR.
"Its a just a little, tiny pebble
likea grain of sand from outer space.
zipping through our atmosphere.
and colliding with the molecules and
atoms in the atmosphere.
and casing them to glow.
It is not star at all,
nothing even remotely similar to a star.
These glowing pebbles are better known as
meteors.
Most burn up in the atmosphere.
Some, if they're large enough
can make it all the way through the atmosphere
and drop to the Earth
and we find a rock
calle d meteorite.
Many come from Asteroid Belt.
The one in 1833,
by some accounts
had as many as 200,000 meteors per hour.
Some observers thought the world was coming to an end.
COSMIC RAYS
These are not rays, these are particles.
They can cause mutation in DNA.
and that leads to variations in species of animals.'
and evolution.
They also may influence the weather.
SPRITES
ELVES
(Emissions of Light and Very low frequency perturbations from Electromagnetic pulse Sources)
BLUE JETS
PHOTOSYNTHESIS
"If photosynthesis were to quit working, we'd all be dead."
(no food to eat, no oxygen to breathe)
That includes animals.
Like us they rely on Sun to regulate their lives.
and just maybe how to navigate their way in the world.
Studies offer some clues to the mystery of how animals navigate.
Many species use the Sun to determine direction.
... And so animals do, in fact, have a biological clock
as do we, which gives them the right time of day.
If conditions obscure the Sun
some animals switch to the Earth's magnetic field.
It provides not only directional pointers, but also positioning cues.
Every place on Earth has a unique magnetic signature.
The problem is the Earth's magnetic fields changes...
PIGEONS
"There are two sense organs that seem to be involved
in detecting the Earth's magnetic field.
One is in the visual system in the eye
in the retina of the eye
and the other is in the pigeon's upper beak
the mandible of the beak
where there are whole bunch of deposits of magnetite
which is a magnetic mineral
and that also seems to be involved in detecting the magnetic field.
So there are tow sense organs
and we still don't really understand exactlyu how these interact,
and how they are used by animals to find way around.
ULTRAVIOLET
UV A
UV B
UV C
"Ultraviolet C blocks almost completely by the ozone layer.
Ultraviolet B gets through a little bit more
and Ultravilet A gets trhough the most.
UV A is considered the aging and sking cancer ray
UV B is considered the burning ray.
While UVB interacts with the sufrace layer of skin
UVA penetrates deeper
adding a new wrinkle to sun exposure.
In fact, tanning booths are even more harmful to the skin.
The reason is because the bulbs are over 90% UVA rays.
Not even sunscreens with a high SPF number
will prevent these harmful effects form the Sun.
(SPF = Sun Protection Protector)
RAINBOW
"The red is one extrem, long wavelenght
The blue is another extreme, which is a short wavelength
there's other wavelenghts in between
that are refracted at different angles
so thatsy why you get that spectrum of light.
Because the change in wavelenghts is continuous
as you go from short up to long wave.
Different wavelengths of light refracted or bent at different angles
explains why the colors of the rainbow
appear in the order they do and in that arc-like shape.
That angle is 42 degrees fomr the anti-solar point.
a fancy astronomical term for the shadow of your head.
At that angle the incoming light is at its most intense
and where the rainbow appears.
But 42 degrees fomr the shadow of your head
is different than 42 degrees form the shadow of someone else's head.
THIS MEANS NO TWO PEOPLE SEE THE EXACT SAME RAINBOW
Sometimes if you're really lucky
or at least standing at the right angle
you'll see a secondary rainbow.
Sometimes (light) bounces (from raindrop) more than once.
And so when it bounces a second time
it comes out at a different angle
its a larger angle.
51 degrees to be exact.
And it'll be dimmer
because most of the light escapes after the first bounce.
Now the interesting thing about the second rainbow
is it's in the opposite order.
So the red that's on one side on one rainbow
will be on the opposite side on the other.
Whether in single or double form
a rainbow doesn't appear at a fixed point in the sky.
Its apparent existence depends solely on the observer's loactaion.
and the posiionof the Sun.
Rainbow is an illusion.
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