Picture captures a billion stars

It is built from thousands of individual images acquired by two UK-developed telescopes operating in Hawaii and in Chile.
Archived data from the project, known as the Vista Data Flow System, will be mined by astronomers to make new discoveries about the local cosmos.
But more simply, it represents a fabulous portrait of the night sky.
"There are about one billion stars in there – this is more than has been in any other image produced by surveys," said Dr Nick Cross from the University of Edinburgh.
"When it was first produced, I played with it for hours; it’s just stunning," he told BBC News.
Dr Cross has been presenting the new work to the UK National Astronomy Meeting (NAM) here in Manchester.

The image concentrates on the dense plane of the galaxy, which means it renders as a very long, very thin strip.
That makes it is virtually impossible to show in a meaningful way on this page.
Dr Cross and colleagues have though produced an online interactive tool that allows the user to zoom in to particular areas. Even then, these smaller fragments of sky will contain thousands of stars.
The project has been 10 years in the making. It combines data from the UKIDSS/GPS sky survey acquired by the UK Infrared Telescope in Hawaii with the VVV survey data acquired by the Vista telescope in Chile.
These astronomical facilities view the sky at infrared wavelengths, enabling them to see past the dust in the Milky Way that would ordinarily obscure observations made at optical, or visible, wavelengths.
UKIRT is responsible for the right end of the image; Vista produced the left, including the more extensive block of coverage which traces the centre of the galaxy and its surrounding bulge of stars. (Black squares in the image are data gaps that are in the process of being filled).
Researchers at the universities of Edinburgh and Cambridge processed and archived all the data that underpins the big picture, and have made it available to astronomers around the world for future study.