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

Webb Joins the Hunt for Protoplanets

We can't understand what we can't clearly see. That fact plagues scientists who study how…

2 hours ago

This Supernova Lit Up the Sky in 1181. Here’s What it Looks Like Now

Historical astronomical records from China and Japan recorded a supernova explosion in the year 1181.…

4 hours ago

Hubble Sees a Star About to Ignite

This is an image of the FS Tau multi-star system taken by the Hubble Space…

5 hours ago

This Black Hole is a Total Underachiever

Anyone can be an underachiever, even if you're an astronomical singularity weighing over four billion…

5 hours ago

Someone Just Found SOHO's 5,000th Comet

The Solar and Heliospheric Observatory (SOHO) was designed to examine the Sun, but as a…

6 hours ago

Astronomers Only Knew of a Single Binary Cepheid System. Now They Just Found Nine More

Measuring the distance to far away objects in space can be tricky. We don't even…

6 hours ago