LONDON-A super telescope has begun the most detailed survey of the Universe ever undertaken.
The aim of the five-year programme is to shed light on Dark Energy - the mysterious force thought to drive an accelerated expansion of the Universe.
The instrument effectively contains 5,000 mini-telescopes. Each one can image a galaxy every 20 minutes.
In just one year scientists will have surveyed more galaxies than all the other telescopes in the world combined.
What is Dark Energy?
The Big Bang theory of the creation of the Universe originally predicted that its expansion would slow down, and that it would possibly begin to contract as a result of the pull of gravity. However, in 1998, astronomers were shocked to discover that not only was the Universe continuing to expand, but that this expansion was also accelerating.
The most widely held view is that something is counteracting the pull of gravity - and that something has been termed Dark Energy.
It has been calculated that Dark Energy makes up most of the Universe. Indeed, the atoms that build planets, stars and galaxies probably account for just 5%.
Prof OferLahav, from University College London, is taking part in the project. He said scientists still knew next to nothing about Dark Energy 20 years after its discovery.
“It is just embarrassing to live in a Universe where you only know 5% of it,” he told BBC News.
“The nature of Dark Energy, and what it is, may well lead to a revolution in physics - the whole of physics!”
DESI will scan more galaxies in a single year than all the telescopes in the world combined
What will the new project examine?
An international team of researchers will use a device called the Dark Energy Spectroscopic Instrument (DESI). It has been retrofitted on to the 4m Mayall telescope at the Kitt Peak observatory in Arizona, US.
Inside DESI are 5,000 optical fibres, each acting as a mini-telescope. This enables the instrument to capture light from 5,000 different galaxies simultaneously, precisely to map their distance from Earth, and gauge how much the Universe expanded as this light travelled to Earth.
In ideal conditions, DESI can cycle through a new set of 5,000 galaxies every 20 minutes.
The further DESI looks into space, the further back in time it sees. This is because of the time it takes for light to reach Earth. The instrument can see objects 10 billion light-years away, which are therefore 10 billion years in the past.