This week, the citizens of the Earth were given a wonderful present. The Gaia Data Release 3 was publicized at 9 UT, June 13. And yes I was awake at 2 in the morning to watch the event. The Gaia satellite has been mapping 2 billion (!!!) points of lights in the sky – stars, galaxies, quasars, and solar system objects. They are measuring positions, distances, motions, colours, and spectra. For an Astro Café talk I prepared about the Gaia Data Release 2, I displayed a plot of the number and angular precision of catalogued stars. From the Hipparchus’ catalog of 1000 stars in 150 BCE to the best Earth-based collections from last century, there was a continuous but slow improvement. But with space-based measurements over the last 20 years, the catalogs have improved by orders of magnitude! And Gaia should continue collecting data through to 2025 to continue this trend.
The branch of amateur astronomy pejoratively labeled “armchair astronomy” sounds very passive, but we delight in the personal journey to discovery, which the professional astronomers afford us by collecting and analysing these extreme data sets. One of my passions is following the trajectory of knowledge from the early astronomical observations to the present. For example, I love to learn how the first stellar spectra measured in the 19th century led to Annie Jump Cannon’s stellar classifications (Only Bad Astronomers Forget Generally Known Mnemonics), leading to the Hertzsprung-Russell colour-magnitude diagram, and further leading to amazing insights such as the age of stars. And now such analyses can be extended to hundreds of millions of stars with the public release of the Gaia data.
The Gaia mission is akin to a gothic cathedral. It is a huge edifice, erected with major societal investment that was accomplished by many, many ordinary people who each do their small part. This edifice is a public good which inspires, and makes us bigger and better human beings.
Randy Enkin, President (email)