- Earth is constantly changing the way it looks,
and there's more happening beneath our feet
than you might expect.
[dramatic music]
Can you tell the difference between these two mountains?
The difference is Earth-shattering.
- The difference between a mountain and a volcano
is that volcanoes
are formed from lava,
whereas mountains are not necessarily formed from lava.
Volcanism changes and shapes our planet
by giving us new landmasses such as Hawaii,
such as Iceland,
and it also builds these tall, mountain-like structures
on the surface of our planet.
And in many cases, it actually helps
to make the ground more fertile for planting
of different types of crops.
- Volcanoes are places on the Earth or other planets
where molten material from the inside comes up
and flows out or explodes out onto the surface.
Volcanoes will form anywhere
that the material from the inside
can make its way to the surface.
Sometimes the material will just shove its way up
and make its own pathway.
Other times it'll follow a fracture or a crack
through the rocks at the surface.
- Faults are just cracks in Earth's crust
that form the boundaries for Earth's tectonic plates.
- One of the things you can actually tell right away
from looking at a volcano is if you look at its slope,
if you just look at the volcano as a whole,
it's just the height divided by the width.
A shallow-sloped volcano was one that was formed
by magma that had a low viscosity, that was runny,
and a steep-sloped volcano
is one that was formed by a magma that was sticky.
When magma moves around, it has to push the rocks around.
And one way that we can measure that
is through the breaking of the rocks
using seismometers.
- Volcanoes play a role in how Earth looks today,
but did you know that volcanoes are on other worlds
in our solar system?
You didn't? Well, that's not your fault.
- Mars has volcanoes.
Actually, the largest volcano in our solar system,
Olympus Mons, is on Mars.
Venus has volcanoes,
Jupiter's moon, Io, has lots and lots of volcanoes.
And there are hundreds of volcanoes on Io's surface
and they erupt daily.
- Not all planetary bodies are made of rocks,
and in fact,
the outer solar system,
the majority of the bodies out there are--
have an icy surface.
And so through heating and other mechanisms,
you can melt ice just like you can melt rocks.
- And so when we have volcanism on these moons,
instead of taking the form of hot rock or lava
that erupts onto the surface,
we have slush that erupts onto the surface.
What we call this cold volcanism,
or this icy volcanism, is cryovolcanism.
You have a planet that has a very smooth surface,
then you know that volcanoes or cryovolcanoes
have been active.
You know that there's been some fluid,
whether that be lava,
or when you're talking about icy volcanism,
icy lava or a cryolava that's erupted onto the surface
and it smoothed the surface out.
- Cryovolcanoes? Cool.
So there are different types of volcanoes
and they can be found all over our solar system.
But how do we know this?
- So the technology that's used to explore volcanoes
that I use the most is basically
data that comes back from robotic spacecraft.
So NASA has sent spacecraft
to many planets and moons.
From these pictures, we're able to determine
how tall these volcanoes are, how wide they are.
These spacecraft also have instruments that tell us about
the composition of those volcanoes.
What we're able to do with that information
is we're able to use, then, computer models
and mathematical equations
to try to figure out how these volcanoes formed,
how runny the lava was that formed them.
- Other ways that we can monitor volcanoes include
paying attention to gases coming out of fractures
around the volcanoes.
A really big volcanic eruption can have global effects.
Something big like Mt. Pinatubo
puts so much ash into the air
that it actually cooled the Earth off
for a little while.
- It's important to study volcanoes
because they teach us a lot
about the interior properties of planets and moons.
So, if we see volcanoes on the surface of a planet or a moon,
we know at one time or another
that the interior was warm enough
to sustain that type of activity.
When we think of our own planet, Earth,
volcanism has been very important.
We have this very nice atmosphere that, you know,
full of nitrogen and oxygen that we breathe here.
Early Earth's atmosphere was actually formed
from gases that erupted from volcanoes.
- It's important to study volcanoes
no matter where they are,
and thanks to NASA, we know more about volcanoes
on our planet and in our solar system.
Talk about explosive science.
For "Real World," I'm Mishay.