The night sky has been an endless source of fascination since the start of human history. For example, the mysterious large-eyed, bronze statues of the ancient Shu Kingdom, discovered at the Chinese archeological site at Sanxingdui, were believed to have been able to look across great distances into the stars. In reality, humans can see very little of the night sky with the naked eye. And, for a long while, people were unable to understand what they could see. Not knowing what the stars were, people in ancient times used their imaginations to create a world in the sky. <br> Our power to investigate and thus understand space changed dramatically when the first telescope was angled at the night sky, increasing as it did the power of the human eye and enabling us to understand that the universe is far larger than was previously imaginable. The planets were seen to be worlds similar to our own, many of them even having their own moons. Soon, it was understood that the Sun was just one star among billions in the galaxy we call the Milky Way. Some 300 years later, we learnt that the Milky Way itself was just one galaxy among billions of others, spread across the blackness of space like great islands of light and matter floating in a vast cosmic ocean. <br> Almost 400 years after the first Earth-based telescope was invented, the Hubble Space Telescope was launched into orbit, giving astronomers-indeed all of us-the first breathtakingly beautiful images of our universe taken from beyond Earth. Nothing in history has allowed us to see so much over such great distances, from enormous clouds of gas where stars are being born, to huge black holes, and even to new planets where we might conceivably find life. Not only that-it has also helped us to work out the age and nature of the universe, and discover the incredible fact that the universe is expanding at an ever-increasing speed. <br> To see even further into the universe, many countries are now engaged in building ever more advanced telescopes. Currently, China operates the world's largest and most powerful radio telescope, the FAST telescope, completed in 2016. The 500-metre dish of the "Eye of Heaven" as it is known, is being used in the search for dark matter, thought to be composed of subatomic particles invisible to ordinary telescopes. This vast dish also has the ability to explore regions of space billions of light years away, right at the edge of the visible universe. <br> The Hubble and the space telescopes constructed after it will allow us to see further and further into space. We will view stars and galaxies billions of light years away and look back at a past that was billions of years ago. Using ever-larger radio telescopes as our eyes, we will one day be able to look back to a time in the very early universe, before the existence of light. But the human quest for knowledge reaches even beyond that. So much of the universe remains unexplored that we are still close to the start of this incredible journey of discovery. <br>