The reason for this is because the speed of light is a constant. When you look at a star, you're actually seeing the star not the way it looks now, but the way it looked years ago, when the light was emitted from the star on its way toward Earth. Looking at a star 10 light-years away means that you're actually looking at what that star looked like 10 years ago, because the light left the star 10 years ago and traveled 10 years to get here. The big bang, by current estimates, was roughly 14 billion years ago, so trying to look back there means developing telescopes that can make out objects that are about 14 billion light-years away ... no mean feat.
These two new European satellites will search not for visible light, like the recently repaired Hubble telescope, but for light in ranges of the electromagnetic spectrum that Hubble couldn't detect. Herschel is, with a 11.5 ft mirror, the largest telescope in space. It will examine the infrared range of light, which will allow it to detect the formation of early protostars that elude the observations in the visible light range. The Planck telescope, on the other hand, will explore the "fossil radiation" from the cosmic microwave background radiation in greater detail, providing greater information about large-scale structures in the universe, such as galaxies.
- AFP - Europe launches 'Big Bang' space telescopes
- Time - Two Telescopes to Measure the Big Bang
- SpaceDaily.com - Factfile on Europe's 'Big Bang' space observatories
- About.com Space/Astronomy - Atlantis Heads for Wednesday Rendezvous With Hubble