Hubble Telescope’s views of enormous spiral galaxy illuminate a big mystery

On Nov 21, 2022

The Hubble Space Telescope has been taking an extended look at a spiral galaxy to help astronomers make improvements in measuring vast cosmic distances.

NGC 7038 is an enormous, oval-shaped spiral galaxy with four blue spiral arms swirling around it and a bright, pale-yellow center. Strands of orange dust also emanate from the heart of the giant hive of stars, with vast numbers of other galaxies visible in the background.

The image was created from more than 15 hours of observations from the Hubble Space Telescope‘s Wide Field Camera 3. The aim of the time-intensive exercise is to calibrate two of the most common distance measurement techniques, which use Type IA supernovas and Cepheid variables, Hubble scientists wrote in a statement. Light from Type IA supernovas diminishes as it travels, while Cepheid variables are stars that brighten and dim at a constant rate that also allows their luminosity to be calculated and used to determine distance.

Accurately determining distances to night-sky objects was one of Hubble’s original science goals and NGC 7038 has been particularly helpful to astronomers measuring distances at vast cosmic scales.

In its more than three decades of efforts, the telescope has helped shed light on one of the most intriguing unsolved problems in astronomy, according to the European Space Agency (ESA). The Hubble constant — which, like the iconic telescope, is named for the late astronomer Edwin Hubble — describes how quickly the universe is expanding. Despite increasing precision, the Hubble telescope’s measurements have not managed to reconcile different values determined by other observatories.

This mysterious mismatch between the two values of the Hubble constant suggests that a new discovery in cosmology is waiting to be made, ESA scientists said in the statement. The James Webb Space Telescope, with its tremendous new capabilities, could help to answer this riddle in the coming years.

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