We are the generation of human beings that are going to know whether or not we're alone in the universe. This episode explores the search of exoplanets, from ancient Greek philosophers to the discoveries made possible with the Kepler Telescope. Unbelievable new worlds, planets made of diamond, planets of raining glass, worlds in collision, some plunging into stars, and others that just might harbor life.
Thanks to today's planet hunters, our views of the universe and of our place in it are undergoing one of the greatest revolutions in scientific history.

We can't compare anything on earth to the biggest things known in space. The Cosmic Web may connect objects in the universe with threads of Dark Matter. The Lyman-alpha blob is a bubble like structure containing countless galaxies--perhaps the biggest object in the entire universe. Regions of radio-emitting gas called "radio lobes" could be even bigger. Then there are super galaxy clusters which are hundreds of galaxies merged together due to cosmic collisions. Discover which is the largest planet, star, star cluster, constellation, black hole, volcano, galaxy, explosions, moon, storm, impact crater and "void" in space.

Scientists genuinely don't know what most of our universe is made of. The atoms we're made from only make up four per cent. The rest is dark matter and dark energy (for 'dark', read 'don't know'). The Large Hadron Collider at CERN has been upgraded. When it's switched on in March 2015, its collisions will have twice the energy they did before. The hope is that scientists will discover the identity of dark matter in the debris. The stakes are high - because if dark matter fails to show itself, it might mean that physics itself needs a rethink.

Earth's history is marked by one cosmic disaster after another, forging the path of human evolution. Asteroid and comet collisions, flares from the Sun, mass extinctions, supernova explosions, cosmic ray bombardment. You name it, we've experienced it. It's kind of a miracle we're here at all. Now, experts explore how the Earth has teetered on the verge of destruction.

Right now cosmic forces prowl the universe and threaten man's very existence. They're asteroids and comets; they've left their imprint on planet Earth, literally. Initially helping to build planets through violent collisions, during this fiery bombardment period they may have even seeded Earth with water and the building blocks for life. Since the turbulent formation of the solar system, these space rocks have continued to impact Earth. Some have been so violent that they've led to mass extinctions, including one that wiped out the dinosaur. New theories suggest that asteroid and comet dust harbour deadly viruses that may have triggered some of our worst pandemics. The possibility of future collisions remains a legitimate threat yet despite their dangers, asteroids and comets may hold vital natural resources, which could actually preserve

We're unlocking the secrets of our planet's voyage and discovering that earth's journey affects us all. The Earth is extremely dynamic. It is spinning on its axis, it's whirling about the sun and it's corkscrewing throughout the this galaxy. And there is the fact than Andromeda and the Milky Way are currently 2.5 million light-years apart, but they're hurtling towards each other at over 250,000 miles an hour. A collision is inevitable. As stars, dust, and gas swirl around each other, gravitational interactions could slingshot our solar system out into intergalactic space.