The European Space Agency’s Gaia probe’s latest result Data Release 3 has achieved the most comprehensive star map that mankind has ever made. It maps 1.8 billion stars in and around our galaxy, covering about 1 – 2% of all stellar objects in the Milky Way. Scientists are using this data to unlock new secrets about Earth’s galactic neighborhood.
The Gaia probe is ESA’s ambitious mission to chart a three-dimensional map of the Galaxy, the Milky Way to reveal the composition, formation, and evolution of the Galaxy. For ages, ancient astronomers, space agencies, and modern-day scientists, equipped with the latest state-of-the-art technology and gadgets, are tracking the movement of billions of stars. They are studying their brightness and trying to decode the secrets that the universe holds.
Launched in 2013, the Gaia mission is following the footsteps of ESA’s 1989 Hipparcos mission which was to measure the positions, distances, and motions of stars with unprecedented precision. This is called “astrometry”. Gaia, the $1 billion mission, was given the go-ahead in 2000 as an upgrade with two much larger 1.5-meter telescopes and 106 charge-coupled devices.
Anthony Brown, an astronomer at the University of Leiden and the lead of Gaia’s data processing team, said they could do better even with the Hipparcos mission working. The Gaia mission surveys the whole sky and collects massive amounts of data. It arrived at the second Lagrange point, an ideal, quiet perch from which to stare at the galaxy, in 2014.
The ESA said Gaia, with its back pointing toward the sun, scans a great circle of the sky every six hours. It spins at a steady, slow rate and takes in tiny pinpricks of light from distant stars. The light is captured by Gaia’s two telescopes, CCDs, photometers, and a spectrometer to measure each star’s position, motion, distance, radial velocity, brightness, and color details. This can decode everything – from a star’s mass to its makeup.
Gaia, over its 10-year mission, will collect data an average of 140 times from each star and other objects it spies. The mission dropped its initial data in 2016. It showed a parallax and proper motion measurements for two million stars. The second set of data was released in 2018 and the third in 2020. ESA says this month’s official release gave the finest set of details about more than 1.8 billion stellar neighbors. It also includes information about 1.1 million quasars, super-bright active nuclei of galaxies. The mission has looked at 158,000 asteroids closely and gathered data on millions of other galaxies in our local universe.
The ESA described this as a “classical star map” and a reference for other missions and telescopes.
