It's Christmastime in the Cosmos

Katrina Miller, New York Times
Dec. 19, 2023

For astronomers peering into the depths of the universe, Christmas came a little early this year.

Using data from the James Webb Space Telescope, NASA released an image last month of a Christmas Tree Galaxy Cluster, a winking collection of galaxies 4.3 billion light-years from Earth. 

Underlying the Christmas Tree Galaxy Cluster was a detection by astronomers of 14 stars that flicker over days or months — like the lights on a Christmas tree.

“Seeing an individual star in a faraway galaxy is a big deal,” said Haojing Yan, an astronomer at the University of Missouri who led the study. “Almost like a miracle,” he added.

The observations are possible because of layers of gravitational lensing, an effect by which the gravity of structures in the universe distorts and magnifies the light of objects in the background, making them visible to astronomers. The flickering of the stars is a result of those “lenses” moving in and out of focus.