Hi folks welcome to eyes on the sky for
the weekend of April 17th 2020. This week
we're gonna feature my favorite planet.
We'll start our talk today looking out
at the blue sky before sunset. Have you
ever wondered why the sky is blue? We
have a blanket of gas around the earth
that we call our atmosphere. The Sun
shines heat and light energy into our
atmosphere and the white or visible
light gets scattered around by the gases
around the Earth. Blue is the shortest
wavelength of visible light and it
bounces all over and reflects back to
our eyes blue sky. What would happen if
we took away the atmosphere? Well first
we'd lose the blue sky. Also we'd see the
sun's light shining on the ground and
we'd see the Sun in the sky but we'd
also see all the other stars at the same
time this is what the view would look
like if we were standing on the Moon. The
Moon doesn't have an atmosphere. Now
lets watch the sunset so we can get to
the night sky. Notice how as the sun's
light bends around the horizon at sunset
we start to see other colors in the
evening sky near the horizon. Yellow
orange pink and red all start to scatter
back towards our eyes.
Well as it turns out our our atmosphere
does a lot more for us than just make
the sky a brilliant blue, make beautiful
sunsets, and hide the stars. Without it
Earth would be a frozen ball of rock a
little bit more like Mars. This is
because of the greenhouse effect named
after the way a greenhouse warms what's
growing inside. As the sun's rays come
through the atmosphere some get
reflected by clouds and such and some
make it all the way to the ground. The
ground absorbs them and then re-emits
that light energy as heat. As that heat
rises back off the Earth some of the
gases in our atmosphere catch it and
keep it bouncing around which has warmed
up the Earth especially in the past
10,000 years or so to a habitable 65
degrees on average. But wait you might be
thinking I thought the greenhouse effect
was bad well in this case it's a little
bit like too much of a good thing no
greenhouse at all frozen rock too much
greenhouse effect let's just look at our
other neighbor the planet Venus. The
atmosphere of Venus is super thick and
dense compared to the Earth if we can
say it's like Earth has one blanket of
gas around its surface Venus has like a
dozen blankets and if you can imagine
wearing that many blankets even on the
chilliest night you'd be really warm
well the Earth's atmosphere is made of
about 78% nitrogen and 21% oxygen and a
little bit of some other stuff.
Venus's atmosphere is 96 percent carbon
dioxide and a little over 3% nitrogen. As
it turns out carbon dioxide which you
breathe out every day is one of these
greenhouse gases the average temperature
on Venus is a staggering 900 degrees
Fahrenheit. Scientists think this is an
example of a runaway greenhouse effect
meaning the cycle kept feeding itself
and it kept getting hotter and hotter
over time. This makes Venus which is hot
enough to melt metal and with a thick
toxic atmosphere a pretty inhospitable
place to live also there's the acid rain
so
is this what we worry about on Earth? Earth
has been cycling carbon through its land
sea atmosphere and all living things for
a very long time and for the most part
our carbon dioxide levels have remained
fairly balanced if we look at historical
data both from modern measurements and
from ancient ice cores though we notice
right around the time of the Industrial
Revolution levels of carbon dioxide in
the atmosphere began to rise into
uncharted territory This is when we
started digging up fossil fuels and
burning them creating an imbalance in
the carbon cycle. Massive deforestation
as humans spread all over the planet and
trying to grow food to feed seven point
eight billion of us also contributes as
we are limiting the places that carbon
dioxide can get recycled. These increases
in the last 200 years have led to the
climate change we're experiencing right
now from which scientists forecast
dramatic impacts are our incredible
beautiful planet that can host a
brilliant diversity of life on this 50th
anniversary of humans deciding that our
home is actually pretty important and we
should be much more careful of how we
treat it we'll end with one of the most
important pictures of the Earth that
we've ever seen from space one which
really helped to spark the environmental
movement. This picture is named Earth
rise and it was taken on the Apollo 8
mission. It was the very first time that
we saw our Earth from space.
Major General William Anders who took
the photo famously said we came all this
way to explore the Moon and the most
important thing is that we discovered
the Earth. Happy Earth week folks tune in
all this week as we showcase a truly
unique planet our very own pale blue dot.
That's it for today folks make sure to
check out our content on all the social
media step outside and appreciate the
Earth this week and keep looking up!
