Build the ultimate Milky Way map: Here’s what scientists have so far

Outside of the realm of astonishing spaceflight, groundbreaking satellites and stunning lunar landings, the European Space Agency is focused on one crucial mission. It is simply to “create the most accurate and complete multidimensional map of the Milky Way.”

The ambitious endeavor is called Gaia, and in recent years ESA has steadily made strong progress with the dream. Researchers in the collaboration have collected tons of spectacular data about the over 1 billion stars in our entire galaxy, and record every juicy detail along the way.

And on Monday, the team reached a massive checkpoint for the project.

Lucky for us, it has also released some remarkable images that include the treasure chest with cosmic secrets gathered so far. This particular milestone is formally referred to as Gaia Data Release 3 – and most importantly, it is one that ESA says is the “most detailed Milky Way survey to date.”

In this dataset you can not only see thousands of solar system objects such as asteroids, moons and other celestial wonders in our galaxy, but you can also look at millions of galaxies and phenomena outside The Milky Way.

A depiction of asteroids in our solar system June 13, 2022.

The position of each asteroid at 12:00 CEST on June 13, 2022 is plotted. Blue represents the inner part of the solar system, where terrestrial asteroids, Mars cruisers and terrestrial planets are. The main belt, between Mars and Jupiter, is green. The two orange “clouds” correspond to the Trojan asteroids of Jupiter.

P. Tanga (Observatory of the Côte d’Azur)

When you look at the statistics of this survey, it is really striking. This new wealth of galactic intelligence includes around 6.6 million quasar candidates with redshift estimates, also known as the extremely bright jets that carry supermassive black holes, and probably their exact location. It has 4.8 million galaxy candidates, around 813,000 multi-star systems, 2.3 million hot stars and much more.

“Gaia is a research mission. This means that while Gaia maps the entire sky with billions of stars multiple times, Gaia will have to make discoveries that other more dedicated missions would miss,” said Timo Prusti, project researcher for Gaia at ESA, in a statement.

A map with points of light showing galaxies and cosmic clouds.

The large and small Magellanic clouds appear as bright spots in the lower right corner of the image. Sagittarius’ dwarf galaxy is visible as a faint quasi-vertical stripe below the galactic center.

ESA / Gaia / DPAC / CU6, D. Katz, N. Leclerc, P. Sartoretti and the CU6 team.

A few interstellar surprises

According to the team, among the most surprising findings of Gaia’s data release are 3 strange phenomena called “star quakes”.

Star earthquakes are pretty much exactly what they sound like – small movements on the surface of a star that can change their orbital shape. Some of these earthquakes ESA compares to vibrations we associate with “large-scale tsunamis” on Earth.

“Star earthquakes teach us a lot about stars, especially their inner workings. Gaia opens a goldmine for ‘asteroseismology’ of massive stars,” said Conny Aerts from KU Leuven in Belgium, and a member of the Gaia Collaboration, in a statement.

Asteroseismology is for stars what seismology is for the earth, the study of earthquakes and other such wave propagation. An overview of the star earthquake part of Gaia’s new data can be seen below.

Another striking revelation was that the Gaia telescope duo – which uses a huge camera of 1 billion pixels – could detect the chemical composition of the stars being studied. This is a big issue that could revolutionize the field of astronomy.

In short, to understand the breakdown of what exact chemicals can help us decode when they were born, where they were born and what path they followed after they were born. It can reveal a timeline for the universe.

And with the new Gaia data, the team found that some stars had heavier elements than others. Heavier elements are often metals, and differ from lighter elements because they have a different core structure.

A description of which stars in the Milky Way are richer in metals.

This full-sky view shows a selection of the Milky Way stars in Gaia’s computer release 3. The color indicates the star metallicity. Redder stars are richer in metals.

ESA / Gaia

But the main point here is that lighter elements, from what experts know so far, are believed to be the only type present during the Big Bang. Essentially, this means that Gaia data release 3 provides direct evidence of a super-diverse combination of stars in our galaxy in terms of both time and place of creation.

“This diversity is extremely important because it tells us the story of the galaxy’s formation,” Alejandra Recio-Blanco of the Observatoire de la Côte d’Azur in France, and a member of the Gaia Collaboration, said in a statement. “It reveals the processes of migration in our galaxy and accretion from external galaxies.”

A sky map showing the speed of the Milky Way stars.

This sky map shows the velocity field of the Milky Way for around 26 million stars. Blue shows the parts of the sky where the average movement of stars is towards us, and red shows where the average movement is away from us.

ESA / Gaia / DPAC / CU6, O. Snaith, D. Katz, P. Sartoretti, N. Leclerc and the CU6 team.

Taking this a step further, seeing Gaia’s efforts remind us in a way of our place in the universe. Mapping a region far, far larger than the Earth’s immediate neighborhood inevitably forces human existence into perspective.

As Recio-Blanco puts it, “It also clearly shows that our sun, and we all belong to an ever-changing system, formed thanks to the composition of stars and gas of different origins.”

Other notable observations with Gaia include over 800 double star systems, which refer to two stars orbiting each other, as opposed to our solar system’s unique sun, and a new asteroid survey involving 156,000 rocky bodies.

A multicolored depiction of asteroids in the Milky Way.

This image shows the orbits of the more than 150,000 asteroids – from the inner parts of the solar system to the Trojan asteroids in the distance to Jupiter. The yellow circle in the middle represents the sun. Blue represents the inner part of the solar system, where there are terrestrial asteroids, Mars cruisers and terrestrial planets. The main belt, between Mars and Jupiter, is green. Jupiter Trojans are red.

P. Tanga (Observatory of the Côte d’Azur)

“We can not wait for the astronomical community to dive into our new data to find out even more about our galaxy and its surroundings than we could have imagined,” said Prusti.

And as for Gaia’s own next steps, the team intends to continue striving for what will ultimately be the pinnacle of knowledge for our home galaxy, the Milky Way.

A description of where we are in the Milky Way.

This image shows an artistic impression of the Milky Way, and on top of that an overlay that shows the location and density of a young star sample from Gaia’s computer release 3 (in yellow-green). The “you are here” sign points to the sun.

ESA / Kevin Jardine, Stefan Payne-Wardenaar