Thousands of unknown galaxies captured by image

Previous heavenly work by the Vista telescope The widest and deepest view of the sky ever made using infrared light has been produced by the European Southern Observatory’s Vista telescope.The image contains more than 200,000 galaxies, with tens of thousands of them previously unknown to astronomers.
The telescope is stationed at the ESO’s Paranal Observatory in Chile and is the most powerful infrared survey telescope in existence.
It has been trained on the same patch of sky repeatedly to slowly accumulate the very dim light of the most distant galaxies.
In total more than 6,000 separate exposures with a total effective exposure time of 55 hours, taken through five different coloured filters, have been combined to create this picture.
What’s more, the area of sky that the telescope has been trained on looks unremarkable to the naked eye - but such is the power of the telescope that a treasure trove of objects has been revealed.
All of the fainter objects in the image are not stars in the Milky Way, but very remote galaxies, each containing billions of stars – and they can only be detected using infrared technology.
This is because the expansion of the universe shifts light from distant objects towards longer wavelengths.
For starlight coming from the most distant galaxies that we can observe, this means that most of the light falls in the infrared part of the spectrum when it gets to Earth.
As a highly sensitive infrared telescope with a wide field of view, Vista, which began operating in 2009, is incredibly useful for spotting distant galaxies in the early universe.
By studying galaxies in redshifted light at successively larger distances, astronomers can trace how galaxies were built up and evolved over the history of the cosmos.
Close inspection of the picture reveals tens of thousands of previously unknown reddish objects scattered between the more numerous cream-coloured galaxies.
These are mostly very remote galaxies seen when the universe was only a small fraction of its present age.