To the delight of astrophysicists around the world, the agency has published precise data on more than two million stars in the galaxy.
The first wave of data from the agency's Gaia mission offers an insight as to what the final three-dimensional stellar map will contain.
"To summarise, the first data release that we are presenting today I think it is a major advance in the mapping of the heavens," said the chairman of the Gaia Data Processing and Analysis Consortium, Anthony Brown.
The pan-European DPAC is made up of some 450 scientists and software engineers, and is charged with the painstaking task of transforming the raw information from the Gaia spacecraft into something useful.
Mr Brown said the data collected contained an unprecedented level of detail.
"That is why I can say this will really cause a revolution in stellar physics," he said.
European Space Agency infographic on first data release from the Gaia Mission. Source: ESA
Gaia Mission
At the heart of the mission is the 10-metre-wide Gaia spacecraft.
Launched in December 2013, it contains two telescopes and three main instruments that precisely determine the location of stars and their speeds.
Data from the spacecraft has been transmitted to three ground stations, including one in the remote Western Australian town of New Norcia.
During its first 14 months scanning the sky, Gaia has collected over 500 billion astronomic measurements, and helped identify some 400 million new stars.
Future data releases will add extra detail, including how fast stars are travelling.
"We will get the characterisation of stars in terms of temperature and composition," said Gaia Mission Manager Fred Jansen.
"We will get the individual measurements at the end of the mission. And that of course is where alot of astronomy can be harvested," he said at the data launch at the European Space Astronomy Centre in Madrid.
The mission will help astrophysicists resolve mysteries about the origin and evolution of the galaxy.
"(Including what) the universe is made of, how it evolves, what is its origin. (And) what is its destination," said the Director of Science at the ESA, Alvaro Gimenez.
Technical Hiccup
The data release, like the mission, was not without obstacles.
A technical hitch at the start of the data launch initially prevented proceedings streaming live online.
Speaking later at the event, Gisella Clementini from the Astronomical Observatory of Bologna in Italy struggled to contain her delight after overcoming the hurdle.
"I should say that it is very difficult for me to be here now because I am so excited," she said.
"I would like to be at my desk downloading Gaia data. So I will sort of rush through my presentation."
The full atlas of the one billion stars is set to be released at the end of 2017.
With AP
