One of Neptune’s Great Dark Spot storms was captured by the Hubble Space Telescope starting in 2015. Astronomers observed a storm on the eighth planet from the Sun in 2018, after spotting white clouds forming, then a dark storm was later seen where those white clouds had been forming.
NASA announced Thursday that its Hubble Space Telescope (HST) has calibrated more than 40 “milepost markers” of space and time. The mile markers help scientists measure the expansion rate of the universe, which is calculated using data from the HST and other telescopes. Astronomers have found — using data from Earth and other points in space — a discrepancy between the expansion rates as measured in the local universe compared to independent observations following the big bang.
The cause of the discrepancy between the two measurements remains unknown, but NASA said Hubble Space Telescope data supports new physics. The expansion rate of the universe is called the “Hubble constant,” after Edwin Hubble.
Edwin Hubble, an astronomer, was the first person to calculate the constant from his measurements of stars in 1929. The constant is used to predict how fast an astronomical object at a known distance is moving away from Earth. It is also used by astronomers to measure greater distances in space by using exploding stars called Type Ia supernovae. The value of the Hubble constant remains up for debate, according to the University of Chicago, Hubble’s alma mater. Cepheids, or stars that periodically brighten and dim, have long been the gold standard of cosmic mile markers. For greater distances, astronomers use exploding stars called Type Ia supernovae.
In a new paper, scientists used data gathered by NASA’s Hubble Space Telescope to measure 42 supernova milepost markers. The collaboration, called SH0ES (Supernova, H0, for the Equation of State of Dark Energy), aimed to “bracket the universe” by comparing supernovas—exploding stars—to measurements of the cosmic microwave background radiation, which is leftover light from the dawn of the universe.
The results of the SH0ES project are more than double the prior sample of cosmic distance markers; this increase in information is important for measuring the expansion rate of the universe. NASA also explained that the expansion rate of the universe was predicted to be slower than what Hubble actually sees, with a lower value for the Hubble constant calculated using the Standard Cosmological Model of the Universe and measurements by the European Space Agency’s Planck mission than its estimate.
Nobel Laureate Adam Riess of the Space Telescope Science Institute (STScI) and the Johns Hopkins University, who leads SH0ES, said that—given the large Hubble sample size of mile markers—astronomers are unlikely to be wrong in their conclusion.