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When the ESA launched the Gaia spacecraft in 2013, it didn't generate the same fanfare as the launch of other missions like the JWST, or first light from telescopes like the Vera Rubin Observatory. That's largely because Gaia doesn't capture gorgeous images of celestial objects like other telescopes. Instead, Gaia was an astrometry mission.

Astrometry is the measurement of the positions, velocities, and magnitudes of stars. Gaia also measured their distances, and the physical properties and radial velocities of many of its targets. Gaia's mission is complete now, but it observed and cataloged more than 1.8 billion celestial objects in its 10.5 year mission.

The result is the most comprehensive map of the Milky Way ever created, or even attempted. Gaia data has made its way into countless published studies and will continue to do so for a long time. It's foundational data and its value will take a long time to diminish or be superseded.

Now the ESA has created a fly-through 3D video that visits stellar nurseries in the Milky Way. A stellar nursery is a molecular cloud that's actively forming stars. They're called nurseries because these massive clouds can spawn large numbers of young stars.

The video takes the viewer to the Gum Nebula, the North American Nebula, the California Nebula, and the Orion-Eridanus superbubble.

The Gum Nebula is about 1,470 light years away and was originally thought to be the remains of a supernova explosion, and it does contain the 11,000-year-old Vela Supernova Remnant. The nebula contains several cometary globules, which actually have nothing to do with comets. Instead they're star formation sites where radiation and wind from young stars creates a tail-like feature.

The North American Nebula is about 2,600 light years away and was discovered by William Herschel in 1786. Its southern appendage resembles Central America and helped astronomers name it after North America. The part is called the Cygnus Wall. The distance to the nebula was uncertain for a long time, until Gaia measured hundreds of its stars.

The California Nebula got its name because of its resemblance to that state's coastline. It's about 1,000 light years away and was discovered in 1884. It's lit up by a hot, blue, O-type star named Xi Persei which has more than 30 solar masses and is more than 12,000 times brighter than the sun.

The Orion-Eridanus superbubble is about 500 light years away, first observed in the 1970s. It's a massive cavity about 1,200 light years across that was carved out by between 10 and 20 supernova, as well as the powerful stellar winds from dozens of massive young stars. Astronomers think that the sun may have passed through this bubble a long time ago and that the iron-60 found in deep-sea sediments comes from its trip through the bubble.