It is estimated that between 40% 50% of all light that is emitted from stars and galaxies in our direction actually reaches us. The other half is absorbed, and diffracted by occasionally planets but more often than not simply the number of tiny grains of dust and hydrogen floating about in space. After all the density of space is about one hydrogen atom per cubic centimeter, which adds up to a lot of atoms over a long distance. However the energy of the light has to go somewhere and so the dust will remit it in the infrared spectrum.
To observe these sources astronomers used the Herschel telescope to construct the most detailed map of deep space energy sources ever created.This survey was called the Astrophysical Terahertz Large Area Survey (ATLAS) and was able to find over 500,000 far away sources of infra red radiation. The study was so detailed it can be used to look at how galaxies evolve over time. Apparently there are noticeable differences between galaxies just a billion years ago compared to galaxies now. As the universe develops the complete volume of hydrogen is getting used up as more and more is fused into heavier metal elements and so the rate of this fusion is slowing down, with galaxies becoming less active in most cases. This project is so revolutionary it was described as the “equivalent of technicolour” compared to black and white celluloid.
This is the perfect opportunity to mention The Brilliant Cosmos a website dedicated to providing knowledge about quite advance theoretical and astrophysics concepts created by a Mr Najam (possibly phd). I have got permission to link the blog whenever I mention one of the topics as part of the news but I would recommend anyone who is interested in learning more of the advanced side of cosmology; going and reading some of the articles.