Eyes in the sky

Over 50 years ago, astronomers launched the world’s first orbiting telescope. This allowed them to gaze further into outer space and examine anything that appears in the sky above our heads, from comets and planets to galaxy clusters and stars. Since then, almost 100 space telescopes have been launched from Earth and are orbiting our planet, with 26 still active and relaying information back to us. As a result of these space-based instruments, such as NASA’s iconic Hubble Space Telescope, we know much more about the universe than we did half a century ago. But why is Hubble, orbiting just 540 kilometres above the Earth, so much more effective than a ground-based telescope? How can a glorified camera tell us not only what distant objects look like, but their detailed chemical composition and three-dimensional structure as well?