Catching Light - Special 50th Anniversary Episode 6

ESOcast 46 is the sixth special episode of this series. It describes how state-of-the-art cameras and spectrographs help ESO’s powerful telescopes collect and analyse the faint light from the distant Universe. Without these instruments, ESO’s eyes on the sky would be blind. Today’s astronomical images are very different from those from the 1960s. Back then, astronomers used large photographic glass plates, which were not very sensitive and hard to handle. Nowadays, ESO’s telescopes use some of the largest and most sensitive electronic detectors in the world. They catch almost every cosmic photon and recover almost every possible bit of information. For instance, the VLT Survey Telescope’s camera — OmegaCAM — has 32 detectors, which team up to produce spectacular images of the Universe, each with an impressive 268 million pixels. But astronomy is not only about taking breathtaking images. Astronomers are always after as much information as possible so they need to dissect the starlight into its component colours to study its composition. Spectroscopy is one of the most powerful tools in astronomy and ESO’s telescopes also have some of the world’s most powerful spectrographs, such as the powerful X-shooter at the Very Large Telescope. Spectroscopy allows astronomers to infer important properties of the stars, such as the chemical elements they contain, their temperatures, motions, and even their ages. Moreover, they can study the atmospheres of exoplanets orbiting distant stars or newborn galaxies at the edge of observable Universe. Watch this episode to discover more about ESO’s state-of-the-art astronomical instruments.