Scientists identify earliest 'green peas' galaxies in Webb's first image; strikingly similar to a rare type located much closer to Earth

NASA's James Webb Space Telescope has uncovered some extremely young distant galaxies that share some remarkable similarities to "green peas" - a rare class of small galaxies in our cosmic backyard.

In 2009, volunteers participating in Galaxy Zoo, a project in which citizen scientists classify galaxies in images from the Sloan Digital Sky Survey, discovered and named green pea galaxies. These galaxies are small, round, and unresolved dots with a green hue, which is a result of the colors assigned to the different filters in the survey's composite images and a characteristic of the galaxies themselves. Peas are quite small, usually only about 5,000 light-years in diameter or about 5% the size of the Milky Way galaxy.

In July 2022, NASA and its partners in the Webb mission unveiled the most precise infrared image of the far-off universe to date, containing thousands of galaxies in and behind the SMACS 0723 galaxy cluster. The three faint objects (enclosed in a circle) seen in Webb's image have properties that are strikingly similar to those of green peas that are located much closer to Earth.

The most distant of these three galaxies was magnified by approximately 10 times, taking advantage of the telescope's remarkable abilities as well as a boost from nature.

Last July, Webb released the deepest & sharpest infrared image ever seen. Zooming in, scientists found 3 young galaxies similar to a rare type of galaxy in our cosmic backyard — including what may be the most chemically primitive galaxy identified. https://t.co/kKCwaFgn9q pic.twitter.com/GirG1GAgdl

— NASA Webb Telescope (@NASAWebb) January 9, 2023

With detailed chemical fingerprints of these early galaxies, we see that they include what might be the most primitive galaxy identified so far. At the same time, we can connect these galaxies from the dawn of the universe to similar ones nearby, which we can study in much greater detail," said James Rhoads, an astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, who presented the findings at the 241st meeting of the American Astronomical Society in Seattle.

The team's findings are published in The Astrophysical Journal Letters.