For those playing along at home, that's about 1.5 trillion times the weight of the Earth's Sun.
Now, the results of the research on Milky Way's mass can open up to new answers to many astrological questions.
Interestingly, astronomers determined that only a tiny percentage of the galaxy's mass could be attributed to the approximately 200 billion stars in the Milky Way.
"For some context, the lowest mass galaxies are around a billion solar masses and the most massive are around 30 trillion solar masses, so the Milky Way is on the higher end of this range-but we already knew that", said Watkins.
"That's what leads to the present uncertainty in the Milky Way's mass - you can't measure accurately what you can't see!" "Compared to other galaxies with similar brightness, the Milky Way's mass is fairly typical". Its second data release includes measurements of globular clusters as far as 65 000 light-years from Earth.
It's a bit of a mouthful, but not as daunting as it sounds. The combined mass and distance of globular clusters make them excellent tracers, or reference points, for measuring the mass of the Milky Way.
"By combining Gaia's measurements of 34 globular clusters with measurements of 12 more distant clusters from Hubble, we could pin down the Milky Way's mass in a way that would be impossible without these two space telescopes", van der Marel added.
Given the elusive nature of the dark matter, the team had to use a clever method to weigh the Milky Way, which relied on measuring the velocities of globular clusters - dense star clusters that orbit the spiral disc of the galaxy at great distances. The results, set to be published in a future edition of the Astrophysical Journal (pre-print here), posits a total mass of the Milky Way at 1.5 trillion solar masses, which extends out some 129,000 light-years from the center of the galaxy.
Roeland P. van der Marel of the Space Telescope Science Institute calls the team lucky for having access to informative data from two different sources. The measurement is by far the most accurate one of the galaxy, thanks to the data provided by NASA/ESA Hubble Space Telescope and ESA's Gaia mission.