Measuring the Milky Way’s mind-boggling mass

A combination of telescope data and 87,000 simulated galaxies helps scientists to size up the Galaxy. Astronomers are closing in on a precise estimate for the mass of the Milky Way.

A view of the central parts of the Milky Way, as seen from Earth

Previous attempts to pin down the Galaxy’s heft have often analysed its gravitational effect on just one of the small ‘satellite’ galaxies orbiting the Milky Way. To broaden that sample, Ekta Patel at the University of Arizona in Tucson and her colleagues used a model that simulates the evolution of the Universe.

The model’s outputs include the masses of the galaxies that form over time and the angular momenta of smaller satellite galaxies orbiting the larger ones.

The researchers analysed more than 87,000 simulated galaxies and their characteristics. The team then performed a statistical analysis to compare the simulation’s results with measurements of the nine known satellite galaxies of the Milky Way.

The closest match between the simulation and the data puts the mass of the Milky Way at between 670 billion and 1,250 billion times that of the Sun.

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