Astronomers using the NASA/ESA Hubble Space Telescope have measured the metallicity of the neutral interstellar medium towards 25 bright stars in our Milky Way Galaxy. Location of the observed O- and B- type stars on the Galactic plane. Image credit: De Cia et al., doi: 10.1038/s41586-021-03780-0. The interstellar medium — the space between the stars — comprises gases at different temperatures and densities and dust particles. The neutral...
