In June 2022, the team from the European astrometry satellite Gaia published a third catalog of data. Here it visualized some of these metrics. The entire sky as visible from Earth was projected onto the surface of an ellipse. The center of our galaxy is right in the middle of the elliptical map. The band of the Milky Way – the stars, gas and dust in the plane of our spiral galaxy – runs from left to right in the center, dividing the ellipse in half.
Now we see the radial velocity at the top left, that is, the velocity of objects – mostly stars – in the direction of view. Color code means that dark areas are coming towards us and light areas are going away from us. It can be measured astronomically using the Doppler effect. Ultimately, we recognize in this the rotation of our galaxy. Extragalactic objects such as the Magellanic Clouds emerge as prominent bright spots in the lower right corner of the map as they move away from us. The black dot to the left of the clouds is the globular cluster 47 Tucanae, which is part of the Milky Way system and is approaching us.
Gaia also produced a dust map. This material is found between stars and is quite cold. The density of dust in color increases from blue to green, yellow and red to black. As has long been known, gas and dust are concentrated in the galactic plane. The velocity field of about 26 million stars is shown at the bottom left. The blue areas are coming towards us, while the red areas are moving away from us. The lines show the movement of stars in the sky. At the bottom right is a chemical map of the fine-grained ellipsoidal stars. Stellar metallic content (metallic) is colour-coded: red dots represent stars that contain more “metals”, meaning chemical elements beyond helium. They are also concentrated in the band of the Milky Way, near the center of our Milky Way.
