There's evidence that dark matter makes up 85% of all the matter in the universe. We can see dark matter holding galaxies together and ripping other structures apart, we even see it bending light. Dark matter itself has been around since the beginning of the universe. Without dark matter, we wouldn't be here. But if you can't see dark matter and if you can't touch it, does it really exist?
Dark Matter is thought to be the cosmic glue that holds the universe together, yet the search for it continues to eluded scientists today.

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.

Experts explore the elusive endeavor of determining the age of the cosmos. Understanding the age of the universe is fundamental to understanding the universe at all. It's at the heart of everything. We want to know how much mass is in it, how much energy is in it, how it behaves. We have to have this number nailed down. The age of the universe enables us to not only understand where we came from, but potentially, the fate of the universe, what will happen millions and billions of years from now.
The idea that the universe grew from a ball smaller than a pinhead is hard to understand, but figuring out when it happened sounds like it should be more straightforward. But it turns out, getting the age of the universe is pretty tricky.

Voyager, the most ambitious space mission in history. They're the first probes to truly explore half the planets in our solar system: Jupiter, Saturn, Uranus and Neptune. These went from dots of light in the sky, to real worlds. The Voyager missions have ventured far beyond where other probes have explored. They're the first spacecraft to taste interstellar space, exploring further than any human made spacecraft has gone before. They are the greatest space mission ever. The legacy of Voyager is our remnant, it is our memory. It is a sampling of humanity that is out there now among the stars. And if they last until the death of the Universe, as the final stars fade, and everything goes dark, they will be humanity's final statement: ‘We were here.’
In the last episode of the season 10, experts explore the ultimate, ongoing mission of the Voyager spacecrafts.

Exoplanets, strange worlds outside our solar system. We're discovering the cosmos is full of alien planets. Alien worlds that challenge our understanding of planetary systems. Hellishly hot worlds, violently colliding worlds, worlds getting eaten by their stars. There's much, much more out there than we had ever imagined.
Exoplanets are shaking up our understanding of the universe. The cosmos is a chaotic array of the odd, the weird, and the wonderful. The more we find, the less we know.

The season 8 of Space Deepest Secrets shares the stories of deep-space explorers who are risking their careers, and even their lives, to lead humanity to worlds yet to be seen.
In the first episode, astronomers are laying the groundwork to locate a new planet for the human race to inhabit, and the more alien worlds they discover and encounter, the more they unmask the mysterious and truly destructive nature of the cosmos.