Behold, the most detailed, stunning star map of our galaxy ever made

25 Apr 2018

Image: Alex Mit/Shutterstock

Painstaking research undertaken by ESA has created a beautiful and stunning map of nearly 1.7bn stars in the Milky Way.

It is hard to comprehend the size of space, but recent efforts from the European Space Agency’s (ESA) Gaia mission have revealed a star map of truly stunning quality, giving us a snapshot of what is really out there.

The map published today (25 April) offers previously unseen details of our home galaxy. After nearly two years of being compiled, it will likely lead to a multitude of discoveries in the decades to come.

The data was collected between 2014 and 2016, pinning down the positions of nearly 1.7bn stars with greater precision than ever before.

By comparison, the first data release following Gaia’s launch at the end of 2013 captured data for just 2m stars.

For some of the brightest stars in the latest survey, the level of precision equates to Earth-bound observers being able to spot a euro coin lying on the surface of the moon.

Star map

Gaia’s all-sky view of our Milky Way galaxy and neighbouring galaxies. The maps show the total brightness and colour of stars (top), the total density of stars (middle) and the interstellar dust that fills the galaxy (bottom). Image: ESA/Gaia/DPAC

‘Truly exceptional’

With this new information, astronomers will be able to separate the parallax of 1.3bn of these stars – an apparent shift on the sky caused by Earth’s yearly orbit around the sun – from their true movements through the galaxy.

Of the 10pc of stars whose parallax measurements are the most accurate, astronomers will be able to directly estimate distances to those stars.

“The second Gaia data release represents a huge leap forward with respect to ESA’s Hipparcos satellite, Gaia’s predecessor and the first space mission for astrometry, which surveyed some 118,000 stars almost 30 years ago,” said Anthony Brown of Leiden University in the Netherlands.

“The sheer number of stars alone, with their positions and motions, would make Gaia’s new catalogue already quite astonishing.”

He continued: “But there is more: this unique scientific catalogue includes many other data types, with information about the properties of the stars and other celestial objects, making this release truly exceptional.”

Galactic archaeology

Not only did the mission map what is going on in the deepest depths of space, it also helped us paint a picture of the number of objects found in our own solar system.

Based on estimates, we now have the positions of more than 14,000 known asteroids, allowing astronomers to predict their orbits and potentially preventing a future collision on Earth.

The news could also spur a new age for ‘galactic archaeologists’ because the data has helped create the most accurate Hertzsprung-Russell diagram of stars ever made.

Named after the two astronomers who devised it in the early 20th century, the Hertzsprung-Russell diagram compares the intrinsic brightness of stars with their colour, and is a fundamental tool to study populations of stars and their evolution.

The new version based on 4m stars within a distance of 5,000 light years from the sun revealed many fine details for the first time. This included the signature of different types of white dwarfs, so much so that a differentiation can be made between those with hydrogen-rich cores and those dominated by helium.

Antonella Vallenari from the Istituto Nazionale di Astrofisica in Italy said: “The new Gaia data are so powerful that exciting results are just jumping at us. It feels like we are inaugurating a new era of galactic archaeology.”

Colm Gorey was a senior journalist with Silicon Republic