Mapping Our Galaxy, the Milky Way Revealed.................by the European Space Agency and its Gaia probe, launched in December 2013. What a great accomplishment - has located a billion stars in our galaxy, and it is just over half-way through its five-year mission! This article says that still is only 1% of the Milky's stellar population!!
Yahoo News
Marlowe Hood•September 13, 2016
Paris (AFP) - The European Space Agency will unveil on Wednesday a three-dimensional map of a billion stars in our galaxy that is 1,000 times more complete than anything existing today.
A space-based probe called Gaia, launched in December 2013, has been circling the Sun 1.5 million kilometres (nearly a million miles) beyond Earth's orbit and has been discreetly snapping pictures of the Milky Way.
The satellite's billion-pixel camera, the largest ever in space, is so powerful it would be able to gauge the diameter of a human hair at a distance of 1,000 kilometres, meaning nearby stars have been located with unprecedented accuracy.
Just over half-way through its five-year mission, Gaia's two telescopes have located a billion stars.
That's still only one percent of the Milky Way's estimated stellar population, scattered over an area 100,000 light years in diameter.
But it is enough to keep professional stargazers busy for years to come, said Francois Mignard, an astronomer at France's National Centre for Scientific Research and a member of the Gaia Science Team.
"Over the centuries we have sought to catalogue the content of the skies," he told AFP.
"But never have we achieved anything so complete or precise -- it is a massive undertaking."
The first data dump "opens a new chapter in astronomy," he added, and is certain to generate hundreds of scientific studies.
Gaia maps the position of the Milky Way's stars in a couple of ways.
Not only does it pinpoint their location, the probe -- by scanning each star about 70 times -- can plot their movement as well.
This is what allows scientists to calculate the distance between Earth and each star, a crucial measure, explained Mignard.
- Thousands of new worlds -
Both types of data will be available Wednesday for more than two million stars.
"That's 20 times more than what we had before," Mignard said. "And all in one fell swoop!"
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