When Mars One invited citizens to journey to Mars, 200,000 people applied. The final 100 include a military jet pilot, an ER doctor, and an IT consultant -- all willing to leave their loved ones forever. They share a common dream -- and a willingness to endure almost unimaginable isolation.
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.
We think of comets as beautiful glowing balls of light streaking across our skies with their long sweeping tails, yet comets are so much more than just a cosmic firework display. Comets have a uniquely important place in modern science. As time machines from the early universe, they could hold the key to unlock the secrets of the cosmos. Comets could even be the origin of life itself. We follow the incredible odyssey of a comet as it sails through the solar system, watching it's every move as it evolves from a dormant chunk of ice and rock into a tumbling, violently active nucleus engulfed in a gaseous haze. What we learn is a revelation; comets are even more mysterious and fascinating than we had ever imagined.
This episode documents how gravity has an effect across the universe, and how the relatively weak force creates an orbit. We also see how a neutron star's gravity works. Finally, there is a look back at how research on gravity has enabled us to better understand the cosmos.