On a dry lakebed in Nevada, a group of friends build the first scale model of the solar system with complete planetary orbits: a true illustration of our place in the universe.
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.
Quantum theory, the best explanation of how atoms and anything smaller behave, is so weird even scientists who have mastered it find it baffling. But bit by bit scientists are finding maybe it's not so weird as comparable behavior is discovered in our every day world. It's just that no one noticed before.
The Earth, the sun, the stars, and everything we can see, only comprise five percent of the universe. But what about the other 95 percent? Scientists are puzzling over dark matter and dark energy, the mysterious components that make up the rest.
The United States and China are considering launching manned missions to Mars -- in 25 years. But Netherlands-based Mars One has a bold plan to land humans on Mars in 2027. Is the mission fuelled by wishful thinking and unproven science -- or will private explorations get us there?