Vol 100, No 8 (2023)

The paper presents an overview of the main foundations of cosmology and its current state.

The article presents an overview of the development of our ideas about new forms of matter in the Universe.

An overview of various methods used to estimate the mass of the Galaxy is given. The results obtained on the basis of the analysis of the galactic rotation curve, on the kinematics of dwarf satellite galaxies of the Milky Way, on globular clusters, on the streams of dwarf galaxies, on distant halo stars, on escape velocities, on the dynamics of the Local group of galaxies, as well as results of N-body modeling are included. Estimates of the mass of the Galaxy \(M\) of the form (i) \(M( < r)\), i.e. the mass enclosed inside a sphere with a radius of \(r\), (ii) \({{M}_{{200}}}\), where r 0 kpc, and (iii) virial estimates, \({{M}_{{{\text{vir}}}}}\). Such estimates were selected by us based on literary data,a significant part of which was obtained in the Gaia era. According to 20 individual estimates, the average value was found \({{\bar {M}}_{{200}}} = 0.88 \times {{10}^{{12}}} {{M}_{ \odot }}\) with a variance of \(0.24 \times {{10}^{{12}}} {{M}_{ \odot }}\) and a weighted average error of \(0.06 \times {{10}^{{12}}} {{M}_{ \odot }}\). According to 28 individual estimates we obtained \({{\bar {M}}_{{{\text{vir}}}}} = 1.05 \times {{10}^{{12}}} {{M}_{ \odot }}\) with variance \(0.44 \times {{10}^{{12}}} {{M}_{ \odot }}\) and a weighted average error of \(0.09 \times {{10}^{{12}}} {{M}_{ \odot }}\).