Recently, a group of astronomers recalculated the mass of the Milky Way, with the help of new data from the Gaia and Hubble space telescopes. Until now, different estimates varied from 500 billion to 3 trillion sun-masses, mainly due to the unknown “dark matter” which is supposed to present the largest part of the total mass, albeit invisible and therefore not directly measurable. Dark matter was introduced to explain high velocities of rotational speeds of outer stars of galaxies. Their calculation results: about 1.5 trillion sun-masses.
However, space is curved. This curvature becomes relevant to the sizes of galaxies, such that curvature has to be incorporated in the calculations. Incorporating curvature leads to far less mass of our galaxy and less or no need for “dark matter”.