The Hubble and James Webb Space Telescopes are world famous, but there’s another space observatory that’s contributing greatly to astronomy: The European Space Agency’s (ESA) Gaia Mission. Like Webb, Gaia orbits about 1 million miles from Earth, well beyond blurring effects of our atmosphere and interference from satellite mega-constellations. But unlike Webb and Hubble, Gaia, which launched in 2013, is a wide-field survey mission that observes the entire sky repeatedly. Gaia measures the brightness and position of stars with unprecedented precision. This allows for direct measurement of the distance and absolute brightness of more than a billion stars. Gaia’s repeated measurements enable astronomers to calculate motions of stars in 3 dimensions. Gaia also records spectra to determine the chemical and physical characteristics of stars.
Using the parallax method, Gaia directly measures stellar distances as great as 30,000 light years with an uncertainty of only 10%. Thirty thousand light years, equivalent to 176,000 trillion miles, is about 1/3 of the way across our Milky Way Galaxy. This is breakthrough science, because using ground-based optical telescopes, it’s challenging to measure distances of more than 500 light years directly.
Major contributions from Gaia include:
- Precise position and brightness for more than 1.8 billion stars
- Color data for more than 1.5 billion stars
- Distances and space motions for more than 1.4 billion stars
- Detailed physical characteristics for more than 4 million stars within 5,000 light years of the Sun (via an H-R diagram)
- Discovery of a nearby dwarf galaxy, called Antlia 2
- And discovery of the Gaia-Enceladus stellar stream, interpreted as the remains of a dwarf galaxy that merged with the Milky Way 8 to 11 billion years ago
The Gaia Mission is providing a detailed understanding of the structure and history of our Milky Way Galaxy and its neighbors in space.
The European Space Agency has extended the Gaia Mission through year 2024. So, expect continuing breakthroughs from this trail-blazing mission! You’ve been listening to “Western Slope Skies”, produced by the Black Canyon Astronomical Society and KVNF Community Radio. I’m Art Trevena.
