"(NARRATOR READING)" "NARRATOR:" "From the beginning of mankind, people have looked up to the stars, wondering what marvels could be found out there." "As science and technology developed, we finally got some answers." "We learned about our neighbouring planets that spin around the sun, just like the Earth." "We found cosmic nebulae of incredible beauty, stars exploding into supernovas and even black holes." "Is mankind ready for its biggest discovery?" "With our instruments, satellites and spacecraft becoming more and more advanced, we are finding more and more distant planets." "Is there another Earth in the vast depths of space?" "And could there be alien life?" "The answers are out there, in our universe." "Earth." "Our beautiful blue planet." "Our home." "Seven billion people live here." "By the sea, on land," "in the mountains and in vast cities." "We have evolved from cavemen to the information society." "Science is exploring all aspects of nature, be it on our planet or beyond it." "Huge archives of data have been created, providing answers to many questions." "We have come a long way from the beginning of the space age, when the first satellites were launched, and man set foot on the moon." "Our probes have visited all the planets of our solar system and delivered a lot of data." "We now have a good understanding of how our home system in this universe works." "There are eight major planets." "Mercury, which is closest to the sun, and very barren." "Venus, with her thick atmosphere and furious volcanoes." "Earth, the only known planet to host life." "And Mars, the Red Planet, a neighbour that has had a lot of human-made visitors." "Farther out is Jupiter, a giant made of gas, with over 60 moons." "Saturn, with its mighty ring system." "And, finally, Uranus and Neptune, the "ice giants"." "Beyond them lie huge asteroid fields and some dwarf planets, like Pluto and Eris." "All these heavenly bodies revolve around the sun." "It's the centre of our solar system and also its superpower." "Without the sun, life on Earth wouldn't be possible at all." "Basically, the sun is a gigantic energy reactor that produces radiation and light." "In order to be able to look at the sun with our human eyes, we need to decrease its luminosity by 98% first." "We are now looking at the pulsating surface." "The temperature here is over 3 million degrees Fahrenheit." "The darker areas are the sunspots." "They are plasma craters the size of the Earth, where temperatures are lower." "The brightest areas, on the other hand, are solar flares." "The plasma there reaches temperatures of up to 10 million degrees." "These flares can cause ripples that look just like ripples on a pond from here, when in fact the waves are 2 miles high, and move at hundreds of thousands of miles per hour." "But the highest temperatures are found in the very core of the sun, going up to almost 30 million degrees, because in here hydrogen is constantly fused into helium." "Through this process of nuclear fusion, the sun releases energy equalling millions of atomic bombs every second." "A great deal of this energy is released in the form of photons." "These photons dart around the core at light speed, but they collide with matter so often, that it takes them thousands of years to finally escape into open space." "From there, they only need about eight minutes to cover the 100 million miles to Earth and arrive here as what we know as sunlight." "But the sun doesn't only supply light." "It's responsible for 99% of the Earth's energy intake." "In the entire history of mankind, we have produced less energy than the sun blows out in a second." "This begs the question, how is such a powerful object created?" "The answer is, it is born from a cloud of cosmic dust and gas." "These vast accumulations of matter can be found all over the universe." "They are called nebulae." "These nebulae come in many shapes and sizes, and many of them are of stunning beauty." "For example, there is the Horsehead Nebula, looking like a stallion rising out of a pink mist." "And the Witch Head Nebula, furiously staring into space with eyes made of gigantic stars." "Or the Flame Nebula that resembles an inferno towering for millions of miles." "We are now looking at the Carina Nebula." "Here, the gigantic star, Eta Carinae, is the father of numerous baby stars." "Eta Carinae has a mass 100 times greater than our sun." "The star dust this nebula is made of consists of crystals, amorphous substances and molecular chains." "This matter is blown apart by the radiating emissions of Eta Carinae." "The particles are pushed away at different speeds, depending on their density." "The results are chaotic shapes of fascinating beauty." "Many different patterns emerge, with finger-like tubes being quite common." "Here is a famous example that has been named the "Pillars of Creation"." "Quite fittingly, because in each of these fingertips, new stars are born." "The matter here is very dense, compressed by solar radiation and gravity." "Eventually, the pressure gets so high, it triggers an atomic explosion." "The new star has ignited." "Instantly, a massive eruption of solar radiation occurs, which develops into a shockwave." "In the Eagle Nebula, we can see such a shockwave in the bright contour at the top of the formation." "This shockwave acts like a battering ram that compresses and ignites matter, continuing the process of star birth." "In some cases, the collected mass isn't big enough, and the young sun fails to keep a nuclear reaction running." "The result is a brown dwarf, an astral body in between a sun and a huge planet." "But if the ignition succeeds, another chain reaction is triggered, one that may ultimately lead to the creation of life." "The gravity of the newborn sun sets the matter around it in motion." "Nearby portions of the nebula are pulled in, and begin to spiral around the sun." "A protoplanetary disc is formed." "As the matter whirls about, a process of accretion begins." "This is an effect of zero gravity that causes particles to cling together." "That way, bigger masses of material start to form." "As these become larger, they grow into asteroids." "Directed by the sun's gravitational attraction, the asteroids move around at high speed." "They crash into each other repeatedly, resulting in the formation of even bigger masses of rock." "Eventually, some of them grow large enough to have a significant gravitational pull, and, therefore, pick up more and more material." "Over time, this process leads them to become planets." "Some of these planets even develop an atmosphere by collecting particles of gas" "?" "oating through the surrounding space." "And our Earth was made the same way." "After a core had formed from materials of our sun's protoplanetary disc, the young Earth was constantly bombarded by asteroids and other celestial bodies." "Back then, Earth was much closer to the sun, and was very, very hot." "Its surface was made of one big ocean of lava." "There was no solid crust, no land, not even water, just heat, lava and fire." "Comets kept crashing into that brooding surface, raising the temperature with every hit." "Eventually, the young planet suffered a massive collision with something huge, another planet in the making." "The impact was so severe, it ripped off a part of the Earth's mantle." "The debris then formed a ring around Earth." "Again through the process of accretion, this rubble formed the moon over the course of millions of years." "Earth, on the other hand, was thrown into a furious rotation by that horrendous impact." "It was spinning so fast, a day lasted only six hours." "After hundreds of millions of years, it gradually slowed down again." "Also, the contents of the sun's protoplanetaly disc were finally used up, having formed the other planets and moons." "Accordingly, the astral bombardment decreased, so the surface could cool off." "This led to the formation of a solid crust of stone." "Still, there were frequent volcanic eruptions." "They spat out lava and gases, and the Earth went through many changes." "Huge meteors of ice had brought water from the depths of space, which now filled the first oceans." "Over time, an atmosphere was formed." "Vaporised water condensed, and returned to the surface in the form of rain." "A hydrological cycle was set in motion and over subsequent millions of years, evaporation and rainfall eroded the rocky surface of Earth." "The Earth's first supercontinent broke apart several times, and slowly, land masses took the shapes of the continents we know today." "So there it was, Earth as we know it today." "Along with its silent companion, the moon." "Being the closest astral body to Earth, the moon has fuelled the imagination of mankind for millennia." "The idea of aliens on the moon has been communicated through paintings, songs and literature." "Even some of the first silent movies depicted life on the moon." "But by the time man first landed on the moon in 1969, it was rightly anticipated that the astronauts would not encounter any moonsfolk." "Still, the moon remains truly fascinating." "Earth's companion is the fifth largest moon in our solar system." "It needs four weeks to orbit once around Earth, a fact that is mirrored in our everyday language." "The word "month" is a derivative of "moon"." "Through its gravitational pull, the moon is responsible for the ebb and flow of tides in our earthly oceans." "It even in?" "uences the navigation and spawning behaviour of some species of fish and insects down here." "As far as looks are concerned, the moon remains a bit dull, because it is completely covered in grey dust." "The dust layer is produced by meteor strikes." "Due to the lack of an atmosphere, they crash onto the surface of the moon without any damping, and are pulverised in the process." "The "moon dust" produced this way actually resembles sand." "Or, scientifically speaking, regolith." "Despite the lack of water up here, we still group the moon's surface into areas of "lands" and "seas"." "This is due to the antiquated belief that the dark areas on the moon contained water." "We now know that those "seas" are in fact basins of solidified lava." "In the moon's early days, its core was still molten." "Heavy asteroid hits broke through the crust, and the impact craters became filled with lava." "Interestingly enough, the moon is still geologically active today." "In fact, moon-quakes occur up to 10 times a day." "Most of these are moderate, but some reach up to Level 5 on the Richter scale." "Fortunately, the rocks up here don't seem to mind." "Even if the moon's landscape is lacking variation, we still have a great view from here." "Our blue mother planet rises majestically and you also get a perfect view of the stars, without an atmosphere or light pollution hindering the outlook, like it does from Earth." "For the same reason, scientists launched gigantic telescopes into Earth's orbit." "They make a great addition to deep-space exploration, providing answers on the creation of the universe itself" "Also, they capture stunning images of stellar nebulae." "A great example is this shot of the America Nebula that shows the formation's resemblance to the North American continent." "The cameras can also register light that is invisible to human eyes." "In infrared view, for example, this nebula looks entirely different, but no less fascinating." "A totally different visual experience is provided by the Rho Ophiuchi cloud complex, which is the star factory closest to Earth." "The 300 suns we find here have an average age of 300,000 years." "That really makes them babies, from a star's point of view." "After all, the oldest discovered stars have been around for over 12 billion years." "The Pleiades, also known as the "Seven Sisters", are also readily visible from Earth." "That makes them the subject of many old scriptures and legends." "These suns were created when dinosaurs were still roaming the Earth, about 100 million years ago." "Some experts believe that our sun also was born in a dense star-forming region like the Pleiades, and moved to its current position over the course of millions of years." "All this information can be deduced from today's opportunities to examine the incredible clockwork that is space." "Early astronomers didn't have that luxury." "In the very beginning, they had to use their naked eye to make out the different stellar objects." "One of the brightest in the night sky was Jupiter, so the Romans named it after their main god." "As telescopes were invented and improved, vision got clearer and clearer." "Today, especially thanks to human space probes like Voyager, we have a very good understanding of this largest planet in our solar system." "The Babylonians called Jupiter the "King's Star", and, indeed, it reigns over its own little realm." "With its 63 moons, some even planet-sized, it can almost be described as its own solar system." "When we take a close look at the planet, the first thing we notice are the colourful cloud formations." "Jupiter is a gas giant, meaning that it's almost exclusively made of gas." "In 1995, the spacecraft Galileo launched a probe into these clouds." "On the way down, it recorded violent wind speeds, and a massively growing pressure." "After diving only 100 miles, the pressure got high enough to crush the probe." "Further down, there isn't much else to see anyway." "As the pressure gets higher and higher, the atmospheric gasses are liquefied without a visible transition." "This means that Jupiter doesn't even have any defined surface we could land on." "A very distinctive external feature of Jupiter's atmosphere is the "Big Red Spot", a gigantic whirlwind with a fixed position." "Its diameter is three times that of Earth, and it doesn't seem to run out of steam" "After all, its existence was already recorded in 1664." "All four of the outer planets Jupiter, Saturn, Uranus and Neptune are gas giants, so they share a lot of similarities, like a lack of a surface." "Saturn looks very special, though." "It is accompanied by a massive ring system." "Saturn is the sixth planet of our solar system." "Even though it's almost 1 billion miles away, it's visible to the naked eye in our night sky." "This is because of its huge size, over 700 Earth-sized planets could fit inside it." "Saturn's distinctive ring system is also gigantic." "Using even the simplest of telescopes, it can be seen from Earth." "But what are these rings made of?" "Once we get closer, we can differentiate between thousands of sharply-defined rings." "As it turns out, they are not as solid as they first appear." "In fact, they are made up of asteroids that circle around the planet." "It's a diverse range of compounds of different sizes, from specks of dust up to 10 metres wide." "Some of the smaller moons of Saturn are ploughing right through these rings." "These moons are called "shepherd" moons, because their orbits ensure that the rings are kept nicely in shape, a shape they have had for millions of years." "Even though Saturn's ring system really stands out, the other three gas giants in our solar system have rings as well." "Those of Jupiter, Uranus and Neptune are not as visible, though." "They are mostly made up of very small particles, like cigarette smoke mixed with some grains of sand." "While Saturn and Jupiter can't be easily confused," "Uranus and Neptune appear very much alike." "They are the most distant from the sun, so they don't get too much warmth and energy." "That's why they are in a subclass of the ice giants." "And Uranus is the icier one of the two, even though it is not as far away as Neptune." "But it lacks any form of internal heat source, which really is an exception in our solar system." "Scientists assume this has something to do with a massive collision Uranus must have had in the past." "Proof of this is the fact that the axis of Uranus is severely tilted." "Seen from Earth, we look at it almost from above." "Neptune, on the other hand, has an internal energy source and, therefore, displays a lot more weather effects." "In the upper layers of the atmosphere, we see gigantic clouds, several thousand miles long." "They form in stripes, because of the high rotation speed of the planet." "At the poles, we have auroras, northern lights that look much more complex than those we have on Earth." "This phenomenon occurs when charged particles of the solar winds enter the atmosphere." "Jupiter's auroras are even bigger, though." "No surprise, as the planet is almost too big to be true." "If it had gathered some more mass during its creation, it could have ignited to become a sun all of its own." "In that case, our solar system would have two suns today." "And while this may sound unusual, our universe has many systems with more than one central star." "In the Orion Nebula, we even find four suns very close to one another." "Also, they are among the biggest suns in the entire cosmos, hundreds of times bigger than ours." "Their incredible power has spawned the creation of thousands of young stars in their vicinity." "Many of these newborn suns are surrounded by protoplanetary discs, where matter is shaped up into asteroids, moons and planets." "Maybe one of those planets will be home to intelligent life one day." "Our vast powerful universe certainly offers limitless possibilities." "New worlds are created on a literally astronomical scale." "Nebulae like Orion cover distances of hundreds of light years, producing thousands of new suns." "But everything that has a beginning, also has an end." "There is not just birth and creation on mind-bending scales, but also chaos and destruction in the same magnitude." "Even incredibly powerful objects like a sun have to die one day." "But when they go, they leave behind sites of new conception, and incredible sights." "The constellation of Taurus is home to one of the most studied objects in visible space, the Crab Nebula." "Its torn and furrowed structures make this nebula look like a star's explosion frozen in time." "Ancient Chinese astronomers were able to witness the actual event in 1054 A.D." "The explosion was described as so bright, it could be seen during daytime here on Earth." "In the 1,000 years that have passed since, the remaining core of the crab-sun has turned into an extremely dense neutron star." "An even more eerie sight is provided by the Helix Nebula." "Here, the result of a supernova resembles a gigantic eye." "This similarity becomes most obvious when viewed in the infrared spectrum." "This disturbing appearance is more than fitting for the fatal events that took place there." "When the sun exploded, all planets and moons of that solar system were either torn apart by gravitational forces or vaporised by the expanding sun" "But at least some comets survived and still make their way through this galactic rubble" "Even if we know a lot about these faraway systems, it's questionable if mankind will ever reach them." "Considering that even if we could travel at light speed, it would take several thousand years to get there." "For now, it makes sense to concentrate on the astral objects in our own vicinity." "And scientists have been very busy here." "The first planet that had a human-built visitor was Venus" "The probe Mariner 2 flew by in December, 1962." "Venus is the second brightest object in the night sky, after the moon." "Sometimes we can even see it during daytime." "The reason for this is Venus' dense light-reflecting atmosphere, combined with its close proximity to Earth." "And, in addition to being our nearest neighbour, Venus is even called the "sister planet" of Earth." "This is because the two of them share approximately the same size, density and mass." "Likewise, the gravitational force on Venus is close to 90% of ours." "But, in spite of these resemblances, there are major differences that spoil any potential for Venus to serve as a holiday destination" "The number one barrier is Venus' atmosphere." "Comprising almost exclusively of carbon dioxide, it is toxic for us." "Even worse is the heat." "The temperature on Venus can reach over 800 degrees Fahrenheit, making it the hottest place in our solar system." "Then there is an incredibly high surface pressure." "The first Russian probes to arrive here in the 1960s were literally crushed by atmospheric pressure." "With the right technology, though, it would still be possible to land a rover on Venus." "Looking around down here can give you an idea of what hell might be like." "Sulphuric clouds, acid rain and active volcanoes are all on the list of local attractions." "In addition, the heavy clouds are rocked by lightning and thunderclaps." "The surface is adorned with huge volcanoes." "Among them is Maat Mons, a giant 5 miles high, 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 ?" "atlands." "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 Inuit 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." "Altogether, the Milky Way has a diameter of about 100,000 light years." "So even if we could travel as fast as light, almost 700 million miles an hour, it would take over 100,000 years to get from one end to the other." "This begs the question how a formation of this size can be held together at all." "The spiral shapes and bright centres of most galaxies give a hint toward the explanation." "All these individual solar systems revolve around a central point of gravity." "But what force in the universe could have such an immense gravity?" "The answer would have shocked astronomers just 50 years ago." "It is a black hole." "They were thought to be science fiction, but these behemoths really do exist." "Basically, they are stars that have imploded from the pressure of their own gravity." "This caused a chain reaction, that draws more and more matter to the centre of the black hole." "In effect, it becomes denser and denser." "Accordingly, the mass and gravity keep increasing, so the black hole grows more and more powerful." "The stars in the bright centre of most galaxies are flung around the black hole like yo-yos, travelling at speeds of millions of miles an hour." "Black holes seem gruesome in one way, because they relentlessly obliterate anything that comes their way." "But most of the suns, planets and moons are a safe distance away, so they are not in any danger of being sucked in." "Instead, the black holes are the central focus for all of them, determining the shape and size of the different galaxies." "A formation like this wouldn't exist without a black hole, and we would miss out on some of the most exciting examples of natural beauty." "Like the Messier 74 galaxy, for example." "It's a classical spiral-shaped galaxy, not unlike our own." "However, the arms of M74 are decorated with bright, pink areas." "Those are clouds of gases, lit up by the ultraviolet light from young stars." "Much more asymmetrical is the appearance of Messier 66, the biggest galaxy of the Leo Triplets." "Its displaced looks are due to the gravitational forces of its two nearby siblings." "Galaxies are drifting through space, which allows for exceptional compositions." "For example, this pair of galaxies known as Arp 273." "Scientists assume that the smaller galaxy has fully passed through the bigger one, and as a result, created a form that reminds us of a rose." "In a couple billion years, our own galaxy may collide with our neighbour, Andromeda." "Something similar has happened with the Antennae galaxies." "These two galaxies merged when they crashed into each other, and the resulting forces have spawned billions of new suns." "And who knows?" "In one of those young solar systems, life could emerge." "Or could it already exist somewhere out there?" "Maybe even much closer to us." "Granted, our local planets don't have the best conditions." "Mercury doesn't have an atmosphere." "It's way too hot on one side, and way too cold on the other." "Venus has no water on the surface, because it evaporates in the heat of the crushing atmosphere." "Mars' atmosphere, on the other hand, is too thin, it can store neither warmth nor water." "And the four gas giants Jupiter, Saturn, Uranus and Neptune, they do not even have a surface." "But there are not just planets that could host life, there are also moons." "Our main planets have over 100 of them in total, and some of these are bigger than the planet Mercury." "An impressive example is lo." "It orbits Jupiter at a distance of 250,000 miles and is about the same size as our own moon." "On getting a closer look at Io, you might describe it as a hell of a moon." "After all, the most distinctive structures on its surface are volcanoes and lava pools of gigantic dimensions." "There are seas of liquefied sulphur, an element covering the whole planet in various aggregate states, from gaseous to liquid to solid." "This gives lo its colourful appearance." "Of all bodies in our solar system, lo has the most active volcanoes." "The constant eruptions hurl scorching lava up to 180 miles high." "Aside from the huge lava pools that are up to 250 miles wide, there are also rivers of lava, that flow hundreds of miles." "Next to the burning heat of the lava, the temperature instantly drops to minus 200 degrees." "Extreme conditions like these can't exactly be called life-friendly environments." "Our next stop in the vicinity appears to be even colder." "We're closing in on Europa." "This moon is covered with an ice crust 6 miles deep." "Europa has a very thin atmosphere, mostly made up of oxygen." "The surface is very bright and is among the smoothest and youngest of all moons." "It features a network of chaotic ridges and trenches which is visually striking." "These so-called Linea are strongly reminiscent of ice fields on Earth." "Since the positions and alignments of the Linea cannot be explained by geological processes, they are a clue to one of the biggest secrets of our solar system." "Under Europa's icy crust lies a huge ocean of liquid water." "This water interacts with the surface, constantly renewing it, and the Linea are created in the process." "Scientists are already thinking about a probe that can drill its way through the ice and dive into the water, the element that spawned the first life on Earth." "Two other important ingredients are oxygen and warmth." "On the surface of Europa, the average temperature is minus 240 degrees." "It is too far away from the sun for any significant warmth to arrive here." "But the gravitation from Jupiter creates tidal forces that heat up Europa's inside and keep the water from freezing." "And there is oxygen, too, released from the ice by cosmic radiation." "According to scientific estimates, the waters here could be more oxygen-rich than our earthly oceans." "So, in spite of all the cold on the surface," "Europa is indeed a hot contender for alien life." "Still, this icy world seems very different from our own." "There is one that is much more Earth-like, namely the biggest of Saturn's moons." "Its size alone is impressive." "In fact, it's even bigger than the planet Mercury, so it has been aptly named Titan." "Titan is the only known moon to have a really dense atmosphere." "Consisting mainly of nitrogen and rich in methane." "On the surface, temperatures are as low as minus 275 degrees Fahrenheit." "Still, Titan has landscapes that look a lot like those on Earth." "Along the equator lies a region called Xanadu, which is about the size of Australia." "Here we find mountains of up to a mile high." "They are made of frozen water, washed out by methane rain." "Due to the low temperatures, this ice is as hard as rock." "There is no liquid water due to the cold, instead, pools and even seas of methane define the landscapes." "In contrast to the methane seas are desert-like areas dominated by dunes." "These dunes are several hundred miles long and up to 500 feet high." "They are made of organic materials that dried out after raining onto Titan's surface." "With all these visual similarities to our Earth, it's easy to imagine life here." "Because of the cold, it is impossible for water-based life forms to exist, but current data from Titan has given us exciting clues." "Scientists speculate that there may be methane-based organisms that consume hydrogen just in the way we consume oxygen." "No one knows what these creatures could be like." "The course of action is clear, though." "We have to send more spacecraft, probes and rovers out there to look under every icy bit of rock." "Still, we have another interesting astral body on our list that is mostly unexplored." "It's a dwarf planet, but it's much closer than those in the Kuiper Belt." "There is another ring of asteroids located between the orbits of Mars and Jupiter." "And, there, we find the icy world of Ceres." "The spacecraft Dawn will be the first to visit here in 2015, to provide detailed information." "But Ceres is also known to be similar to Europa, maybe it even has a subglacial ocean." "This is especially exciting, as even Earth was once completely frozen over, while life in the subglacial ocean was retained." "There are many wonders to be found out there, even in our own solar system." "So who can tell what the chances of extraterrestrial life are in the entire universe?" "Look at this image." "At first glance, it seems to be a typical snapshot of our night sky, with a lot of stars." "Actually, this isn't too far off." "The surprise is that the area we see here is so small, it's only a tenth the space the moon takes up in our field of view." "And what we see shining there aren't just stars." "No, all these little lights are full-blown galaxies." "Just imagine that." "Behind a piece of our sky about the size of a fingernail, there are more than 10,000 galaxies." "Each galaxy contains billions of solar systems, so even if there is no other case of intelligent life in our solar system, what about the probability when we multiply these chances by a trillion?" "For now, we can only speculate, and dream about the fascinating worlds that could be waiting out there." "Out there in our universe."