字幕表 動画を再生する 英語字幕をプリント Our world, warm, comfortable, familiar... ...but when we look up, we wonder: Do we occupy a special place in the cosmos? Or are we merely a celestial footnote? Is the universe welcoming or hostile? We could stand here forever, wondering. Or we could leave home, on the ultimate adventure. To discover wonders. Confront horrors. Beautiful new worlds. Malevolent dark forces. The beginning of time. The moment of creation. Would we have the courage to see it through? Or would we run for home? There's only one way to find out. Our journey through time and space begins with a single step. At the edge of space, only 6O miles up... ...just an hour's drive from home. Down there, life continues. The traffic is awful, stocks go on trading... ...and Star Trek is still showing. When we return home, if we return home... ...will it be the same? Will we be the same? We have to leave all this behind. To dip our toes into the vast dark ocean. On to the Moon. Dozens of astronauts have come this way before us. Twelve walked on the Moon itself. Just a quarter of a million miles from home. Three days by spacecraft. Barren. Desolate. It's like a deserted battlefield. But oddly familiar. So close, we've barely left home. Neil Armstrong's first footprints. Looks like they were made yesterday. There's no air to change them. They could survive for millions of years. Maybe longer than us. Our time is limited. We need to take our own giant leap. One million miles, 5 million, 2O million miles. We're far beyond where any human has ever ventured. Out of the darkness, a friendly face. The goddess of love, Venus. The morning star. The evening star. She can welcome the new day in the east... ...say good night in the west. A sister to our planet... ...she's about the same size and gravity as Earth. We should be safe here. But the Venus Express space probe is setting off alarms. It's telling us, these dazzling clouds, they're made of deadly sulfuric acid. The atmosphere is choking with carbon dioxide. Never expected this. Venus is one angry goddess. The air is noxious, the pressure unbearable. And it's hot, approaching 900 degrees. Stick around and we'd be corroded, suffocated, crushed and baked. Nothing can survive here. Not even this Soviet robotic probe. Its heavy armor's been trashed by the extreme atmosphere. So lovely from Earth, up close, this goddess is hideous. She's the sister from hell. Pockmarked by thousands of volcanoes. All that carbon dioxide is trapping the Sun's heat. Venus is burning up. It's global warming gone wild. Before it took hold, maybe Venus was beautiful, calm... ...more like her sister planet, Earth. So this could be Earth's future. Where are the twinkling stars? The beautiful spheres gliding through space? Maybe we shouldn't be out here, maybe we should turn back. But there's something about the Sun, something hypnotic, like the Medusa. Too terrible to look at, too powerful to resist. Luring us onwards on, like a moth to a flame. Wait, there's something else, obscured by the Sun. It must be Mercury. Get too close to the Sun, this is what happens. Temperatures swing wildly here. At night, it's minus 275 degrees... ...come midday, it's 800 plus. Burnt then frozen. The MESSENGER space probe is telling us something strange. For its size, Mercury has a powerful gravitational pull. It's a huge ball of iron, covered with a thin veneer of rock. The core of what was once a much larger planet. So where's the rest of it? Maybe a stray planet slammed into Mercury... ...blasting away its outer layers in a deadly game of cosmic pinball. Whole worlds on the loose careening wildly across the cosmos... ...destroying anything in their path. And we're in the middle of it. Vulnerable, exposed, small. Everything is telling us to turn back. But who could defy this? The Sun in all its mesmerizing splendor. Our light, our lives... ...everything we do is controlled by the Sun. Depends on it. It's the Greek god Helios driving his chariot across the sky. The Egyptian god Ra reborn every day. The summer solstice sun rising at Stonehenge. For millions of years... ...this was as close as it got to staring into the face of God. It's so far away... ...if it burned out, we wouldn't know about it for eight minutes. It's so big, you could fit one million Earths inside it. But who needs numbers? We've got the real thing. We see it every day, a familiar face in our sky. Now, up close, it's unrecognizable. A turbulent sea of incandescent gas. The thermometer pushes 10,000 degrees. Can't imagine how hot the core is, could be tens of millions of degrees. Hot enough to transform millions of tons of matter... ...into energy every second. More than all the energy ever made by mankind. Dwarfing the power of all the nuclear weapons on Earth. Back home, we use this energy for light and heat. But up close, there's nothing comforting about the Sun. Its electrical and magnetic forces erupt in giant molten gas loops. Some are larger than a dozen Earths. More powerful than 10 million volcanoes. And when they burst through, they expose cooler layers below... ...making sunspots. A fraction cooler than their surroundings, sunspots look black... ...but they're hotter than anything on Earth. And massive, up to 2O times the size of Earth. But one day, all this will stop. The Sun's fuel will be spent. And when it dies, the Earth will follow. This god creates life, destroys it... ...and demands we keep our distance. This comet strayed too close. The Sun's heat is boiling it away... ...creating a tail that stretches for millions of miles. It's freezing in here. There's no doubt where this comet's from, the icy wastes of deep space. But all this steam and geysers and dust... ...it's the Sun again, melting the comet's frozen heart. Strange. A kind of vast, dirty snowball, covered in grimy tar. Tiny grains of what looks like organic material... ...preserved on ice, since who knows when... ...maybe even the beginning of the solar system. Say a comet like this crashed into the young Earth billions of years ago. Maybe it delivered organic material and water... ...the raw ingredients of life. It may even have sown the seeds of life on Earth... ...that evolved into you and me. But say it crashed into the Earth now. Think of the dinosaurs, wiped out by a comet or asteroid strike. It's only a question of time. Eventually, one day, we'll go the way of the dinosaurs. If life on Earth was wiped out, we'd be stuck out here... ...homeless, adrift in a hostile universe. We'd need to find another home. Among the millions, billions of planets... ...there must be one that's not too hot, not too cold, with air, sunlight, water... ...where, like Goldilocks, we could comfortably live. The red planet. Unmistakably Mars. For centuries, we've looked to Mars for company... ...for signs of life. Could there be extraterrestrial life here? Are we ready to rewrite the history books, to tear up the science books... ...to turn our world upside down? What happens next could change everything. Mars is the planet that most captures our imagination. Think of B-movies, sci-fi comics, what follows? Martians? It's all just fiction, right? But what if there really is something here? Hard to imagine, though. Up close, this is a dead planet. The activity that makes the Earth livable shut down millions of years ago here. Red and dead. Mars is a giant fossil. Wait. Something is alive. A dust devil, a big one. Bigger than the biggest twisters back home. There's wind here. And where there's wind, there's air. Could that air sustain extraterrestrial life? It's too thin for us to breathe. And there's no ozone layer. Nothing to protect us against the Sun's ultraviolet rays. There is water... ...but frigid temperatures keep it in a constant deep freeze. It's hard to believe anything could live here. Back on Earth, there are creatures that survive in extreme cold, heat... ...even in the deepest ocean trenches. It's as though life is a virus. It adapts, spreads. Maybe that's what we're doing right now... ...carrying the virus of life across the universe. Even in the most extreme conditions, life usually finds a way. But on a dead planet? With no way to replenish its soil, no heat to melt its frozen water? All this dust, it's hard to see where we're going. Olympus Mons, named after the home of the Greek gods. A vast ancient volcano. Three times higher than Everest. There's no sign of activity. Since its discovery in the 1970s, it's been declared extinct. Hang on. These look like lava flows. But any sign of lava should be long gone, obliterated by meteorite craters. Unless, this monster isn't dead, just sleeping. There could be magma flowing beneath the crust right now... ...building up, waiting to be unleashed. Volcanic activity could be melting frozen water in the soil... ...pumping gases into the atmosphere, recycling minerals and nutrients. Creating all the conditions needed for life. This makes the Grand Canyon look like a crack in the sidewalk. Endless desolation... ...so vast it would stretch all the way across North America. But here, signs of activity, erosion, and what looks like dried up river beds. Maybe volcanic activity melted ice in the soil... ...sending water gushing through this canyon. Underground volcanoes could still be melting ice, creating water. And where there's water, there could be life. The hunt for life is spearheaded by this humble fellow... ...the NASA rover, Opportunity. It's finding evidence that these barren plains... ...were once ancient lakes or oceans that could have harbored life. Look at those gullies. Probes orbiting Mars keep spotting new ones. More proof that Mars is alive and kicking... ...that water is flowing beneath its surface right now. Water that could be sustaining Martian life. Now, all we have to do is find it. Maybe we've already found what we're looking for on Earth. Some think that life started here and then migrated to Earth. An asteroid impact could've blasted fragments of Mars... ...complete with tiny microbes out into space... ...and onto the young Earth where they sowed the seeds of life. No wonder we find Mars fascinating, this could be our ancestral home. It could be we are all Martians. The Mars we thought we knew is gone... ...replaced by this new, active, changing planet. And if we don't know Mars, our next door neighbor... ...how can we even imagine what surprises lie ahead? Our compass points across the cosmos... ...back in time 14 billion years... ...to the moment of creation.