Across the universe, galaxies are going dark, and scientists don't know why the stars are losing their shine. Something is slowly drawing the curtains closed on the universe. Our milky way is under threat. Astronomers race against time to uncover the truth behind how galaxies are born and how they die before all of the lights go out.

The Milky Way, our galaxy, is a magnificent sight in the night sky, but we know surprisingly little about it for certain. What is its shape? How many stars does it actually contain? What lies at its centre? The Gaia space telescope will answer these questions, being armed with the most advanced camera to leave our planet, and it will allow us to see our galaxy as we've never seen it before. The Sky at Night visits the factory in Chelmsford that made the astonishing sensor at the heart of the mission.

An exploration of Earth's cosmic neighbourhood. Looking beyond the borders of our solar system, what's nearby in our galaxy? How do the other objects in our local area influence life on Earth? And, how did Earth's place in the galaxy make it the perfect place for the development of advanced life? Now that the Voyagers have visited the outer planets of the solar system they are heading for new adventures in places astronomers call the Oort Cloud, the heliopause, heliosheath and eventually they may encounter double stars and exoplanets, some of which may pay a visit to the solar system one day or explode showering us with radiation. If the Voyagers live so long they will experience the local fluff, local bubble and other parts of the habitable zone of the galaxy.

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.

We used to think that Earth was at the centre of the universe, but now we know we're not even at the centre of our own galaxy. Countless wonders exist between where earth is situated and the massive black hole at the galactic centre of our galaxy. Within the Milky Way can be found the debris of old, dying stars fuelling the birth of new stars and at the galactic centre hypervelocity stars get catapulted clear beyond the Milky Way's outer rim at unimaginable speeds. Come along for a guided tour of 100,000 light-year-wide family of stars and stellar phenomena we call The Milky Way.

The center of our galaxy is one of the most nightmarish places in the cosmos. It's the home to some of the most incredible forces the universe has to offer. Gas streaming everywhere, stars are being born and dying and exploding, radiation blasting out. And at the very heart is the super massive black hole, 4 million times the mass of the sun. But also the Milky Way, is our safe harbour, our island in this vast, cosmic ocean. And so to understand the heart of our galaxy, is to understand our home in this cosmic void.