Mapping the History of Space & Time

The longer a telescope spends looking at a target, the more sensitive the observations become, and the deeper we can look into space. But to get the full picture of what s happening in the Universe, astronomers also need observations at a range of different wavelengths, requiring different telescopes. These are the key ideas behind the Great Observatories Origins Deep Survey, or GOODS for short. The GOODS project unites the world s most advanced observatories, these include ESO s Very Large Telescope, the NASA/ESA Hubble Space Telescope, the Spitzer Space Telescope, the Chandra X-ray Observatory and many more, each making extremely deep observations of the distant Universe, across the electromagnetic spectrum. By combining their powers and observing the same piece of the sky, the GOODS observatories are giving us a unique view of the formation and evolution of galaxies across cosmic time, and mapping the history of the expansion of the Universe. Now, this is not the first time that telescopes have been used to give us extremely deep views of the cosmos. For example, the Hubble Deep Field is a very deep image of a small piece of sky in the northern constellation of Ursa Major. This revealed thousands of distant galaxies despite the fact that the whole field is actually only a tiny speck of the sky, about the size of a grain of sand held at arm s length. Now, with GOODS, many different observatories have brought their powers to bear on two larger targets, one centered on the original Hubble Deep Field in the northern sky, and one centred on a different deep target, the Chandra Deep Field South, in the southern sky. The main GOODS fields are each 30 times larger than the Hubble Deep Field, and additional observations cover an area the size of the full Moon. These areas of the sky were already some of the most extensively explored, and so the combination of existing archival data and many new, dedicated observations gives us an unprecedented view of of the history of galaxies.