A Better Map of the Milky Way — and Beyond
A view of the Milky Way from Germany

A Better Map of the Milky Way — and Beyond

The European Space Agency last week shared some of the first fruits of its Gaia satellite: by far the most detailed 3D map yet of the Milky Way galaxy.


With Gaia’s data, scientists can now position some 1.142 billion stars, 400 million of them previously unknown. That’s nearly 20 times the number in the previous best map, plotted by the ESA’s Hipparcos satellite between 1989 and 1993.

Yet it’s only what Gaia’s revealed in the first 14 months of a five-year mission. Still, there’s a long way to go — our galaxy holds an estimated 100 billion stars.

Orbiting 932,000 miles from Earth, Gaia sports a 1 billion-pixel camera that can measure a human hair’s diameter from 600 miles away.

With past data from Hipparcos and other probes, the new info lets scientists estimate distances and motions for around 2 million stars — a boon to understanding their movement through the galaxy.

Some 450 scientists and software engineers worked on processing and checking the data. Gaia’s data opens a revolution in astronomy, notes Anthony Brown of Leiden University, the astronomer who chairs that consortium of analysts. It will let them “investigate our place in the universe, from our local neighborhood, the Solar System, to galactic and even grander, cosmological scales.”
Who knows? Scientists might someday learn enough to allow humans to visit what they’re mapping.

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