M31 and M33 are two of the nearest spiral galaxies, and can form the basis for determining distances to more remote spiral galaxies and constraining the expansion rate of the Universe (the Hubble constant). Hence the relevance and importance of several new studies that employed near-infrared data to establish solid distances for M31 (Andromeda) and M33 (Triangulum) (e.g., Gieren et … Continue reading "Astronomers Refine Distances to our Closest Spiral-Galaxy Neighbors"