Space photo of the week: James Webb telescope shocks scientists with image of ancient galaxy roaring back to life

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The James Webb Space Telescope has zoomed in on Leo P, a tiny galaxy with some big things to say about star formation.

An image of a galaxy
The James Webb Space Telescope's image of the Leo P dwarf galaxy. (Image credit: NASA, ESA, CSA, Kristen McQuinn (STScI))

What it is: The Leo P dwarf galaxy

Where it is: 5.3 million light-years away in the constellation Leo

Why it's so special: Large galaxies like our own Milky Way come from small "seed" galaxies, which grow, collide and merge over time, with each interaction causing more stars to form as gas and dust mix together. However, some of the original seed galaxies still exist in the universe, having remained unchanged for billions of years and containing few chemical elements besides hydrogen and helium.

One such galaxy is an irregular dwarf galaxy called Leo P (the "P" stands for "pristine"), which is far enough away from the Local Group of galaxies — the cluster of large galaxies including the Milky Way and Andromeda — to remain unaffected by their influence.

Related: 25 gorgeous nebula photos that capture the beauty of the universe

Leo P is similar to the primordial galaxies of the early universe, so astronomers can learn a lot about early cosmic history by studying it. Although first discovered in 2013, new data from the James Webb Space Telescope (JWST) has revealed that Leo P is unexpectedly forming new stars.

An image of a galaxy

An uncropped version of the Leo P image. (Image credit: NASA, ESA, CSA, Kristen McQuinn (STScI))

That's a big surprise to astronomers because small, isolated galaxies like Leo P were thought to have switched off their star-forming factories when the universe was about a billion years old, during a cosmic era known as "the Epoch of Reionization." It followed the cosmic dark ages, which refers to a period during the early universe when the dense fog of neutral hydrogen gas blocked light. When the first stars formed then exploded as supernovas, they spread energetic ultraviolet light capable of ionizing hydrogen atoms, or splitting them back into electrons and protons, according to NASA.

See for yourself

Celestron NexStar 8SE

(Image credit: Amazon)

We reckon the Celestron NexStar 8SE is the best motorized telescope out there for zooming in on galaxies like Leo P, as it's great for astrophotography, and offers stunning, detailed imagery. For a more detailed look, you can check out our Celestron NexStar 8SE review.

Using JWST's Near Infrared Camera (NIRCam) to determine the brightness and colors of thousands of stars within the dwarf galaxy, researchers found that Leo P formed stars early on in the universe but stopped doing so shortly after the Epoch of Reionization. That was expected. However, the researchers also discovered that the galaxy reignited after a few billion years and started forming new stars again. Astronomers have gathered similar measurements for three other isolated galaxies, but found that star production ceased within all of them and never resumed, so it's unclear why Leo P reignited.

JWST will now study four other isolated dwarf galaxies to find more clues about how star formation has changed over time.

Jamie Carter
Jamie Carter
Live Science contributor

Jamie Carter is a Cardiff, U.K.-based freelance science journalist and a regular contributor to Live Science. He is the author of A Stargazing Program For Beginners and co-author of The Eclipse Effect, and leads international stargazing and eclipse-chasing tours. His work appears regularly in Space.com, Forbes, New Scientist, BBC Sky at Night, Sky & Telescope, and other major science and astronomy publications. He is also the editor of WhenIsTheNextEclipse.com.

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