Earth is the only home we've ever known, and it's treated us well so far. But whether it’s climate change, an apocalyptic asteroid, or some horrifying disaster we don’t even know about yet, the Earth won't live forever.
The oceans define the earth. They are crucial to life and we used to think that they were unique to our blue planet. But we were wrong. It has recently been discovered that there are oceans all over our solar system, and they are very similar to our own. And now scientists are going on an epic journey in search of new life in places that never seemed possible. Nasa is even planning to dive to the depths of a strange, distant ocean in a remarkable submarine. Horizon discovers that the hunt for oceans in space is marking the dawn of a new era in the search for alien life.
Today Phil’s explaining the stars and how they can be categorized using their spectra. Together with their distance, this provides a wealth of information about them including their luminosity, size, and temperature. The HR diagram plots stars’ luminosity versus temperature, and most stars fall along the main sequence, where they live most of their lives.
Beneath the hood of your car lies the history of the Universe. The iron in your chassis, the gold in your stereo and the copper in your electronics all owe their existence to violent cosmic events that took place billions of years ago.
The majority of the universe is made up of a currently mysterious entity that pervades space: dark energy. We don’t know exactly what it is, but we do know that dark energy accelerates the expansion of space. We think this means the Universe will expand forever, even as our view of it shrinks while space expands faster all the time.