Free Astronomy Magazine July-August 2026

JULY-AUGUST 2026 new particles, or modifications to gravity — its predictions for the present-day expansion rate would be affected. In that case, the Hubble tension may not be the result of measurement error, but rather evi- dence that the current model of the Universe is missing a key compo- nent. The local distance network also establishes a framework for fu- ture investigations. By making its methods and data openly available, the collaboration has created a foundation that can be expanded with new observations. With next- generation observatories expected to provide even more precise meas- urements, astronomers aim to deter- mine whether this discrepancy will ultimately be resolved or continue to point toward new physics. T his graphic represents the tension that exists between measurements of the expansion rate of the late, nearby Universe, versus what would be expected based on meas- urements of the early Universe, specifically the cosmic mi- crowave background (CMB). Under the standard model of cosmology, these two approaches are expected to yield the same result, but they don’t. This discrepancy is known as the Hubble tension, and is represented in this graphic by the misalignment between the Early Route and Late Route “bridges.” Currently, the best estimate for the Hubble con- stant based on measurements of the CMB is about 67.2 kilo- meters per second per megaparsec. In 2026, the H 0 Distance Network (H 0 DN) Collaboration delivered the most precise di- rect measurement of the local Hubble constant to-date, re- porting a value of 73.50 ± 0.81 kilometers per second per megaparsec, corresponding to a precision of just over 1%. [NOIRLab/NSF/AURA/J. da Silva/J. Pollard] !