Categories: Astronomy

219 Million Stars Create the Most Detailed Catalogue of our Milky Way Yet

On the darkest of nights, thousands of stars are sprinkled across the celestial sphere above us. Or, to be exact, there are 9,096 stars observable across the entire sky. Divide that number in half, and there are 4,548 stars (give or take a few) visible from horizon to horizon.

But this number excludes the glowing band stretching across the night sky, the Milky Way. It’s the disk of our own galaxy, a system stretching 100,000 light-years across. The naked eye is unable to distinguish individual specks of light, but the Isaac Newton Telescope (INT) on La Palma in the Canary Islands has recently charted 219 million separate stars in this disk alone.

For the last 10 years a team of astronomers led by Geert Barentsen from the University of Hertfordshire has been collecting and compiling light from all stars brighter than 20th magnitude, or one million times fainter than the human eye can see (at 6th magnitude).

They created a beautiful density map of the Milky Way, giving them new insight into the structure of this vast system. The black, fog-like regions are galactic dust, which blocks more distant light. The brighter regions are densely packed stars.

The INT took measurements in two broad filters, which captured light at the red end of the visible spectrum, and in one narrow filter, which captured light only from the hydrogen emission line, H-alpha. The inclusion of H-alpha enables exquisite mapping of nebulae, glowing clouds of hydrogen gas.

The production of the catalogue is an example of modern astronomy’s exploitation of “big data.” But it would also grace the walls of any art studio.

Shannon Hall

Shannon Hall is a freelance science journalist. She holds two B.A.'s from Whitman College in physics-astronomy and philosophy, and an M.S. in astronomy from the University of Wyoming. Currently, she is working toward a second M.S. from NYU's Science, Health and Environmental Reporting program. You can follow her on Twitter @ShannonWHall.

Recent Posts

Scientists Have Figured out why Martian Soil is so Crusty

On November 26th, 2018, NASA's Interior Exploration using Seismic Investigations, Geodesy, and Heat Transport (InSight)…

4 hours ago

Another Way to Extract Energy From Black Holes?

Black holes are incredible powerhouses, but they might generate even more energy thanks to an…

9 hours ago

Plastic Waste on our Beaches Now Visible from Space, Says New Study

According to the United Nations, the world produces about 430 million metric tons (267 U.S.…

1 day ago

Future Space Telescopes Could be Made From Thin Membranes, Unrolled in Space to Enormous Size

As we saw with JWST, it's difficult and expensive to launch large telescope apertures, relying…

1 day ago

Voyager 1 is Forced to Rely on its Low Power Radio

Voyager 1 was launched waaaaaay back in 1977. I would have been 4 years old…

2 days ago

Webb Confirms a Longstanding Galaxy Model

The spectra of distant galaxies shows that dying sun-like stars, not supernovae, enrich galaxies the…

2 days ago