Science

One of the biggest questions in astronomy is how galaxies were formed and how they have changed over time. We know that there are three main classes of galaxy: spirals, ellipticals and irregulars which are all very different in appearance and content.  These differences suggest that these galaxies might have been formed in different ways, but how? If we could look back in time, we could see what actually happened.   We can actually do this in astronomy because the speed of light, though very large, is finite, which means that looking out into space is the same as looking back in time. When we observe a galaxy at a distance of one billion light years, we see it as it looked one billion years age.  This cosmic time machine gives the astronomer a huge advantage over archaeologists, in that they can see history rather than have to piece it together from its debris.   

Why Herschel? It is the largest, most powerful infrared telescope ever flown in space and is the first space observatory to observe from the far-infrared to the submillimetre waveband, unveiling the mysterious hidden cold Universe to us for the first time.  The Herschel ATLAS is designed to understand the formation and evolution of galaxies and will observe galaxies from the nearby Universe and galaxies which formed when the Universe was only a few billion years old. 

The original proposal is here and the survey paper (Eales et al 2010) is here.  The main science projects using Herschel ATLAS data are:

Digging the Dirt on Galaxies - the nearby Universe
We will detect hundreds and thousands of galaxies in the nearby Universe providing the first extensive census of dust and hidden star formation in the Universe today.
Dusty Stellar Nurseries
Although this is an extra-galactic survey, we still expect to see some Galactic material in some parts of the sky, getting in the way of the distant galaxies!
Galaxies through a Lens
Distant galaxies are sometimes lensed by a massive object between us and the galaxy, allowing us to view these distant galaxies as they were billions of years ago.
The (dusty) Cosmic Web
The Herschel ATLAS is designed to understand the formation and evolution of galaxies and will observe galaxies from the nearby Universe out to redshifts of 3 to 4, when the Universe was only a few billion years old.
Active galaxies and rare objects
Herschel ATLAS should detect about 500 galaxies which are known as active because they have a bright core, harbouring massive black holes.
Herschel and Planck working together
The high resolution of Herschel images will allow us to determine the nature of cold sources detected by the Planck satellite.
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