Our Universe 3D Page #4

towering over the other Venusian volcanoes.

In total, there are over 50,000 of them.

Another distinctive feature of Venus

are its lava channels of incredible size.

One of them even out-competes the Nile,

Earth's longest river.

It's called Hildr Fossa,

and measures 4,200 miles long.

Even though Venus is our nearest neighbour,

the best-explored extraterrestrial planet

is Mars.

This makes sense, as it would be much

better suited for actual human visitors.

Scientists are currently expecting

a manned mission to the Red Planet

in the '30s or '40s of this century.

So what do we know so far?

Mars is a rocky body, just like Earth.

But it's only half the diameter of Earth,

which makes it the second smallest planet

of our solar system.

Its red colour comes from high amounts

of iron oxide, also known as rust,

that is spread throughout the planet

and its atmosphere.

The air here consists of carbon dioxide

and is very thin,

so Mars cannot store

much of the sun's warmth.

Near the equator, temperatures are around

32 degrees Fahrenheit during the daytime.

At night, it plummets to minus 121.

To explore these conditions in detail,

mankind has sent a number of rovers up here.

And aside from environmental data,

they have also captured

some really nice views.

In summer,

the pole caps made of ice melt down,

which allows for

distinctive cirrus clouds to form.

We can actually see these in the sky here.

In spring, storms are common, which

whip up large quantities of Martian dust.

With wind speeds up to 300 miles an hour,

400 kilometres an hour,

a lot of the surface is

cast under a dusty veil.

Sometimes, even small cyclones

called "dust devils" come up.

The landscapes on Mars

offer quite a bit of variation.

In the cooler north, we find the low plains,

which are broad dust-covered flatlands.

The southern hemisphere has

geologically older formations

and more craters.

The biggest Mars crater

is called Hellas Planitia.

Its basin has a diameter of 1,300 miles,

2,000 kilometres,

and its bottom marks

the lowest point on the entire planet.

Running in parallel to the equator

are the Valles Marineris.

These "Mariner Valleys" are the largest

network of canyons in our solar system.

They stretch out for over 2,500 miles,

and are up to 440 miles wide.

In the western part they develop

into a maze-like system of valleys

called Noctis Labyrinthus,

the "Labyrinth of the Night".

Speaking of vast proportions,

Mars holds at least two more records.

One being the volcano with the widest base

area, a giant named Alba Patera.

In relation to its 1,000-miles diameter,

its height of 4 miles isn't too impressive,

but Mars also has the Olympus Mons,

reaching 16 miles high,

and the highest elevation

in our whole solar system.

Apart from Earth,

Mars is by far the planet most thoroughly

explored and researched by mankind.

We know that Mars must have had a much

denser atmosphere millions of years ago,

and probably had liquid

water on its surface.

Back then, it offered much better conditions

for the creation of life.

That changed when its atmosphere

was thinned out by solar winds.

Still, in the ice of its polar caps,

there could be primitive life

in the form of bacteria or microbes.

After all, such life has been found

in the perpetual ice of our own poles.

And while the chances for life on Mars

might have been better in the past,

they could be far worse,

like those on Mercury for example.

Things are downright hostile there.

Mercury is the last "Earth-like" planet

in our solar system.

Actually, apart from having

a rocky body like Earth,

it has not many other earthly properties.

Visually, this planet resembles the moon.

This corresponds well with Mercury being

the smallest regular planet

in our solar system.

And just like the moon,

Mercury has no atmosphere at all,

which is evident

from the crater-littered surface.

From up here, these craters may

look like innocent footprints in sand,

but once we get closer, they reveal

their true size. They are gigantic.

The largest one is known

as the Calorie Basin.

It has a diameter of over 1,000 miles.

This means it must have been caused

by the impact of an astral body

more than 60 miles wide.

Mercury is the planet closest to the sun.

Because of this proximity,

its sun-facing half is heated

to extreme temperatures

reaching 750 degrees Fahrenheit.

On the dark night side, on the other hand,

temperatures go as low as minus 275 degrees.

These conditions make Mercury

the planet with the widest range

of temperature variation.

The day-cycles are similarly extreme.

Due to Mercury's eccentric spin

around the sun,

a night on Mercury lasts for 176 Earth days.

On Mercury, we are almost at the centre

of our solar system.

While a lot of data has been gathered

on the planets and the sun here,

the outer reaches of our domain

still hold a number of secrets.

Beyond Neptune lies the Kuiper Belt,

a vast field of asteroids.

It is home to over 70,000 objects

of more than 60 miles in size.

These objects are left over from

the creation of our solar system,

material that wasn't included

in the formation of our planets.

Some of these objects gained

more respectable mass.

Best known among them is Pluto.

Identified in the year 1930,

it was the first discovered dwarf planet.

And in 1978,

its companion Charon was found.

The two of them rotate around each other,

as if they were doing a little waltz

through space.

Near the beginning of the second millennium,

more and more dwarf planets

were discovered.

The biggest one among them is Eris.

It's about a fifth the size of our moon

and its bright surface

is made of frozen methane.

Just like their full-grown counterparts,

all dwarf planets have been

named after earthly deities.

Makemake is a Polynesian god,

Sedna, the lnuit goddess of the sea,

and Haumea,

the Hawaiian goddess of child birth.

Still, all of these are

hardly more than asteroids,

drifting through cold, dark space.

The real wonders are outside the boundaries

of our solar system.

After all, our sun is only one star

of an estimated 400 billion in our galaxy,

the Milky Way.

And recent calculations have

come to the conclusion

that over half these suns could

have one or more Earth-sized planets.

So let's have a closer look at the structure

of our home galaxy.

From Earth, you can see parts

of the Milky Way with your naked eye.

It's made from the light

of millions of faraway stars,

arranged in a disc-like structure.

Since we are looking at it from the inside,

it appears to be a band of milky fog

across the sky.

Seen from outside, two mighty spiral arms

define the appearance of our galaxy.

These arms are occupied

by particularly bright stars.

The dark areas in between are by no means

empty, but the suns there are less powerful.

Our own solar system lies far outside

the centre of our galaxy,

within the Orion-Cygnus Arm.

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