Solar System Script

(NOAA Logo)

Welcome to NOAA's Science On a Sphere. You are looking at the world's
first spherical movie screen. This is not a hologram; it's a 6-foot,
free hanging plastic ball, which is carbon-reinforced. The system uses
special software to render videos for the spherical surface and four
projectors. Science On a Sphere is the invention of Dr. Alexander
MacDonald, of the National Oceanic and Atmospheric Administration. Now
let's go on a short tour of the Solar System!

(Advance to Sun)

The first stop is the sun, a giant ball of burning gas and the closest
star to Earth. The matter in the sun comprises about 99.8% of all the
matter in the solar system. The remaining .2% goes to all the other
planets and moons and the asteroid belt. The Sun is an astonishing
861,800 miles in diameter. The sun is also a huge thermonuclear reactor.
At its core, the process of nuclear fusion, which is simply hydrogen
atoms fusing together to form helium, is constantly taking place. This
creates a great deal of heat and energy, which we benefit from here on
Earth. Fusion has been occurring in the Sun for about four and a half
billion years, and there is enough energy in it to last about another
four and a half to five billion years, so the Sun is at about half of
its life span. Since the sun is not a solid object, the equator, or
center, actually rotates faster than the polar areas by about 10 days.
What you see here is the corona, or the outer layer, of the sun. You
never want to look directly at the real Sun, but its okay to look at
this video of it. While the sun's brilliant surface is about 10,000°F,
the thin outer corona is much hotter at about 1,000,000°F. The bright
yellow flashes of light you see are actually solar flares. These are
storms on the surface of the sun. Scientists at NOAA watch for these
flares because they can create problems here on Earth. The high-energy
particles and radiation from the solar flares excite the upper
atmosphere of Earth, the part we call the ionosphere, and the outer
magnetosphere. This can interfere with communications like cell phones
and satellites. The high-energy particles and radiation also create the
Aurora Borealis, or Northern Lights.

(Advance to Mercury)

Next on our tour is Mercury, the planet closet to the sun. Or, half of
Mercury. We've only seen one side because it rotates very slowly, and
spacecraft so far have always flown by at similar vantage points.
Mercury rotates three times for every two orbits around the sun. And
since it's only 36 million miles from the Sun, it's too hot for us to
send a spacecraft to the sunny side of Mercury. Mercury is so close to
the sun that its orbit is only 88 days. You might be noticing that
Mercury looks a lot like the moon. That's because it doesn't have an
atmosphere, just like the moon. One thing an atmosphere does for a
planet is provide protection from meteors and rocks. Without an
atmosphere to protect Mercury, it has become covered with craters.
Another result of not having an atmosphere is a sharp temperature
contrast. The sunny side of Mercury is about 750°F, while the cool side,
or the side facing away from the Sun is a much colder 350°F below zero;
a sharp contrast of about 1100°F. As you'll find out on this tour of the
Solar System, there are not many hospitable places to live other than
Earth. These pictures of Mercury were taken by the Mariner Spacecraft in
1974 and 75.

(Advance to Venus)

Now, on to Venus. Actually, this is a radar brightness image of Venus.
This video doesn't show the atmosphere of Venus, which is quite thick,
and made of sulfuric acid clouds. The brighter spots are often rougher
terrain. Venus is a very volcanic place. The atmosphere is comprised
mainly of carbon dioxide. Venus has about 25,000 times the CO~2~ of
Earth. And that much CO~2~ does two things. First, it creates a runaway
Greenhouse Effect. The CO~2~ traps infrared radiation, or heat that
normally travels out to space. So it's very HOT on Venus, in fact, it's
the hottest planet in the solar system at 900°F! Second, the atmospheric
pressure is really high on Venus. It's about 92 times as much as our air
pressure. This is about the pressure a deep sea diver would encounter at
a depth of 3000 feet underwater. So if you were on Venus you'd be
compressed to about the size of a toothbrush. Hot and squished, not a
fun place to live. At one point, Venus may have had oceans, but they've
since evaporated and been lost to outer space. Its orbit is 225 days,
and its distance from the sun is about 67 million miles. Because Venus
is the brightest planet, it is often the evening star in the sky. Of
course, it's not really a star.

(Advance to Earth/ Blue Marble)

Our next stop should be a familiar place, the Earth. The orbit of Earth,
which is the length of one year, is 365.26 days; because of this we have
to rearrange our calendar with Leap Days and Leap Years to make it come
out right. This is a picture of the Earth over three days, which at any
time is about 50% covered in clouds. You can see the continents in green
and brown and the oceans in blue. This is just what it would look like
if you were an astronaut in outer space. The Earth's tilt is 23.5°,
which gives us our seasons. During the summer (in the Northern
Hemisphere), we are tilted toward the sun, causing temperatures to rise.
The Earth is about 8,000 miles wide, and it gets the most sunlight at
the equator, on average. All of the Earth's weather is caused by what we
call differential heating, which just means that some parts of the
Earth, such as the equator, get more heat from the sun than others. This
temperature imbalance has to be worked out by wind and weather patterns.
We're 93 million miles from the Sun, and the Earth is 71% water, about
29% land. Notice that the Earth is not covered in craters because there
is an atmosphere to provide protection.

(Advance to the Moon)

The moon, however, does not have an atmosphere to protect the surface
from meteors and rocks. This is the cause of the marked up surface. The
Moon doesn't shine with its own light. It reflects sunlight, so it's
like a big mirror in the sky. The moon is about 1/4^th^ the diameter of
Earth, and 1/80^th^ of the mass. The temperature range is pretty great;
the side of the Moon that always faces us, the sunny side, is 253°F
while the dark side is --387°F, making a difference of over 600°F! The
Moon is mainly responsible for the tides of the oceans, and it goes
through its phases from full to new, and back to full again in about 28
days. Neil Armstrong was the first person to walk on the moon, on July
21 (the Apollo 11 landed on the moon on July 20), 1969. The moon's a
pretty dusty, rocky, plain place. The astronauts said the dirt felt like
snow, but smelled like spent gunpowder. That's because it's made of a
silicate rock, which apparently made the command module return flight a
little smelly. We may get to go back to the moon, and maybe we'll have
our first girl walk on the moon. In 2004, President Bush signed an
initiative for NASA to go back for longer missions to the moon.

(Advance to Mars)

Now, this is the Red Planet, Mars. It is red because of the iron oxide
dust on its surface, which has the consistency of talcum powder. We are
exploring Mars currently more than any other planet. There are 3
orbiting spacecraft, and 2 exploration rovers, Opportunity and Spirit,
currently on the surface. Both were designed for several months study,
but they're still going after 4 years. We'll be learning even more about
Mars when the Phoenix lander makes it there in May of 2008. The next
mission may discover more about if life ever existed on Mars, because it
will go closer to these...

(TILT MARS)

These are ice caps; the northern one is larger. They're made of frozen
water, normal ice and carbon dioxide. (REORIENT)

Mars has a couple of very interesting features. This deep long scar is
the Valles Marineris. It is the biggest canyon known in the Solar
System. Its 2500 miles across, the distance from New York to Phoenix,
and it is 5.7 miles deep. The Grand Canyon, for comparison, is only 1
mile deep. Another record-breaking feature of Mars is Olympus Mons. It
is the largest mountain (and volcano) known in the Solar System. Its
over 85,000 feet high! The highest point on Earth is Mt. Everest, which
is about 29,000 feet, so Olympus Mons is almost three times that height.
It was able to achieve such an impressive height because there are no
plate tectonics on Mars. The volcano that created Olympus Mons continued
to pile up solid material without the plates below it moving, unlike our
Hawaiian island chain which is the result of moving plates.

(Advance to Jupiter)

Our next stop on this solar system tour is the largest planet. Jupiter
has a diameter 11 times that of Earth. If you took all the other planets
and smashed them together, Jupiter would still be larger. We are now at
a distance of 482 million miles from the Sun. This video of Jupiter is
based on photographs from the Cassini spacecraft that flew there in
2000. It may have a solid core about the size of Earth, but mostly it's
a gas giant. Its motion is very fast (though slower than the inner
planets). It travels around the sun in only 12 years, which is pretty
quick. And it rotates at an incredible speed, completing one rotation in
just 9 hours and 50 minutes. In fact, Jupiter, which has the fastest
rotation rate in the solar system, bulges at the equator and flattens at
the poles due to its rapid rotation. For something that large, that's
quite a spin. Since it is primarily gas, there's some pretty wicked
weather on Jupiter. That's what formed this... the GREAT RED SPOT. It is
a huge storm. It's similar to a hurricane of sorts that is the SIZE of
the Earth! And it has been going on for over 325 years!

(Advance to Io)

The fifth moon of Jupiter is probably the most interesting visually.
This is Io, the third largest moon of Jupiter. We call it the pizza
moon, because that is what it looks like. The black circles are
volcanoes; Io has over 400 of them. Because of the strong pressure
within Io from being pulled by Jupiter and its other moons, these
volcanoes send up sulfur-rich deposits; some of the sulfur dioxide then
falls like snow coating the moon. There is little possibility of life on
Io. But amino acids could possibly form there because of the rich
nutrients. We'd like to explore Io more, and the New Horizons spacecraft
just flew by Io on its way to Pluto.

(Advance to Europa)

Compared to Io, life is more likely on the sixth moon of Jupiter,
Europa. It is thought that there is a global sub-surface ocean in Europa
that is about 12 miles beneath the surface and up to 62 miles deep. This
underground ocean is nutrient rich, providing a place for amino acids to
form. Europa is roughly the size of the Earth's moon. There are
relatively few craters on Europa because the surface of the moon is
young. The young surface is composed mainly of water ice with various
impurities embedded within. The mysterious linear features are from
stresses that are largely tidally generated.

(Advance to Saturn)

This next planet might look unfamiliar to you without its rings. Saturn,
known for its rings, is the 6^th^ planet from the sun and the 2^nd^
largest. The rings of Saturn are made of ice, dust, and rock, with about
60 moons embedded within them. There are 3 main bands of the rings,
which extend between 4,000 and 100,000 miles outward from the equator.
If we showed them here on the scale of the SOS, they would only be about
the thickness of a bacterium (100 nanometers). Saturn also rotates
really fast, spinning around in about 10 hours. It has wind speeds up to
1,100 miles per hour. Saturn is about 900 million miles away from the
Sun, which is about 10 times further away than the Earth is from the
sun. It's a gas giant, made of hydrogen and helium. Saturn's core has a
temperature of 21,400°F and it radiates more heat and energy out to
space than it receives from the Sun. The Cassini spacecraft has been
studying Saturn since 2004, and by 2008 will have made 70 trips around
it! In all of these trips we have found out something fascinating about
Saturn that we never knew before! At the North Pole, there is a gigantic
hexagon! This is a 6 sided vortex with winds of 200 miles per hour. On
the South Pole, a storm with a well defined eyewall was discovered. This
is the first known eyewall to exist outside of Earth.

(Advance to Enceladus)

Let's move on to the whitest object in the whole solar system! This ice
moon of Saturn is Enceladus. Since this has frozen water on it, there's
the possibility that life could have, or may still exist on (or within)
it. Not human life, but perhaps amino acids. Because it's an ice moon,
it's very cold. However, the coolest thing about Enceladus is that there
are about 20 gigantic geysers bursting out of its south pole! These are
plumes of liquid water and steam. It seems that the gravitational torque
inside the moon heats up and cracks the southern surface. This causes
gases and liquid to be ejected from the moon. What scientists have
discovered is that it's this exhaust from Enceladus that created the
E-ring around Saturn! We'd like to explore this icy moon more.

(Advance to Titan)\
\
The next stop is the largest moon of Saturn, Titan. It's 50% bigger than
our moon, and even bigger than Mercury. The atmosphere is primarily
nitrogen and methane which is similar to the atmosphere of early Earth.
This might be an indicator that life (or at least important biological
molecules) could have formed on Titan! Researchers have taken those two
gases, and put them in a chamber. Then, they shined ultraviolet light
and radiation like sunlight through them, and zap! Amino acids were
formed; the building blocks of life. The atmosphere that encircles the
moon creates a surface pressure 50% greater than that around Earth. The
combination of gases in Titan's atmosphere, mixed with sunlight, has
created thick smog around the moon, similar to that seen over large
cities. There's no liquid water on Titan. Also, it's -300°F which makes
it very cold. But there are hydrocarbon lakes at its North Pole. The
Huygens probe landed on the surface, and found that it was some kind of
goo! Not solid, not liquid, but a pudding like goo. Cassini is
continuing periodic flybys of Titan building up a more detailed picture
of its surface. Prior to the Cassini flybys, a clear view of Titan's was
not available.

(Advance to Uranus)

We now come to the two blue planets. This first one is Uranus. It's blue
(or greenish) because of methane in its atmosphere. William Herschel
discovered it in relatively recent times in 1781. It has a very high
mass and density, and is made of frozen water, ammonia, and methane. On
our tour, we are now 2 billion miles from the Sun, so Uranus'
temperature is a very chilly --323°F. It has an 84-year orbit around the
Sun. What makes Uranus so unique is that while most of the other planets
revolve around their axis and spin like a top in just about the same
plane as they orbit the Sun, Uranus has a 98-degree tilt. So it rolls
over and over itself as it travels around the Sun.

(Advance to Neptune)

Now, on to the other blue planet, Neptune. It's also blue from methane
in its atmosphere, along with a lot of hydrogen and helium. When this
picture was taken by the Voyager spacecraft, Neptune had a dark spot
caused by a storm, like Jupiter's Great Red Spot. Unlike Jupiter's Great
Red Spot, the storm on Neptune is not persistent or stationary. The
storm was first discovered in the Southern Hemisphere, but when the
Hubble Telescope photographed the planet later, the Southern Hemisphere
storm was gone and a new storm had formed in the Northern Hemisphere.
Neptune is also a very unpleasant place to live. Its temperature is
353°F below zero! And it has winds of up to 1200 miles per hour! There
is a group of white clouds referred to as The Scooter which races around
the planet every 16 hours. It's a very windy place, though the theories
about what powers the winds are all somewhat speculative. It is thought
that the very hot core of Neptune might play a part in the strong
surface winds. Researchers are trying to learn more about its hot core,
and the cause of the winds.

(Advance to Pluto)\
\
This is the last stop on our tour of the Solar System, but this is no
longer a planet, it's a dwarf planet. This is Pluto. Unfortunately, this
is currently our best picture of Pluto. Because Pluto is an astounding
3,670,050,000 miles from the sun, it is hard to get close enough to get
a good picture. This picture was taken by the Hubble Telescope (with
some Earth-based color information added). We're going to get a better
look at Pluto with the New Horizons spacecraft, which will pass Pluto in
2015. It's made of rock and ice, and is 1,400 miles wide. Until 2006, it
was the 9^th^ planet. But in that year, the International Astronomical
Union set up new guidelines for what it takes to be a planet. There are
3 things you need:

1.  You have to be in orbit about the Sun, which Pluto is.

2.  Next, you have to have enough gravitational pull of your own to
    retain a spherical shape, whether you're made of gas or solid. And
    Pluto does do that.

3.  But, it does not pass the third test. You have to have swept out
    everything else within your path around the Sun. Pluto is not
    dominant enough to have done that, because there are larger objects
    within and beyond its orbit in the Kuiper belt. Here's the wording:
    a [planet](http://en.wikipedia.org/wiki/Planet) will have cleared
    the neighbourhood of its own [orbital
    zone](http://en.wikipedia.org/wiki/Planetary_orbit), meaning it has
    become gravitationally dominant, and there are no other bodies of
    comparable size other than its own
    [satellites](http://en.wikipedia.org/wiki/Satellite) or those
    otherwise under its gravitational influence.

Now that we have visited Pluto, our tour of the Solar System on Science
On a Sphere is complete. Thank you for joining NOAA on this exciting
journey.