Astronomers have identified a complex sugar molecule floating in a cloud of gas and dust near the center of the Milky Way. The discovery of erythrulose, a sugar also found in raspberries and self-tanning products, gives scientists another clue about how the chemical ingredients needed for life may have formed and spread throughout space.
A Sweet Surprise in Interstellar Space
The molecule was detected in G+0.693-0.027, a large molecular cloud located near the heart of the Milky Way. Molecular clouds contain cold gas and dust where atoms can join together to create increasingly complex compounds.
Erythrulose is a four-carbon sugar known as a ketose. While other sugar-related molecules have previously been observed in space, the research team described this as the first confirmed detection of a true sugar in the interstellar medium, the thin material found between stars.
Sugars are important for much more than taste. They provide energy for living cells and help form the structures of DNA and RNA. Discovering how they can develop outside Earth may help researchers better understand the chemical steps that took place before life began.
Radio Telescopes Reveal a Molecular Fingerprint
Researchers studied the molecular cloud using the Yebes 40-meter telescope and the IRAM 30-meter telescope in Spain. These radio telescopes can detect signals released by molecules rotating in space.
Every molecule produces a unique pattern of radio frequencies, much like a fingerprint. The astronomers compared signals from the cloud with laboratory measurements of erythrulose and found multiple matching spectral lines. The agreement allowed them to identify the sugar in gas form from thousands of light-years away.
University of Arizona astrophysicist Erika Hamden, who was not involved in the research, called the molecule “a pristine example of the stuff that’s just floating out in the galaxy.”
Building Complex Chemistry on Cosmic Dust
Scientists believe erythrulose may form on the icy surfaces of tiny interstellar dust grains. Chemical models suggest that simpler two-carbon molecules, including glycolaldehyde and ethylene glycol, can react under extremely cold conditions to produce the larger sugar.
The finding was surprising because scientists often expect interstellar molecules to grow gradually as carbon atoms are added one at a time. However, the new research suggests that combining smaller molecular building blocks could produce complex sugars more efficiently.
Study co-author Izaskun Jiménez-Serra explained that “The prevailing view in astrochemistry is that interstellar molecules grow in size through the sequential addition of carbon atoms.” The results suggest that other chemical pathways may also play an important role.
New Clues About the Origins of Life
Erythrulose itself is not considered essential for life. However, when exposed to water, it can change into threose, another four-carbon sugar that may have played a role in early chemical systems connected to replication and metabolism.
Sugars such as ribose and glucose have previously been found in meteorites and samples from asteroid Bennu. The latest discovery strengthens the possibility that complex organic molecules formed in space before the solar system existed and were later delivered to the young Earth by comets and asteroids.
Jiménez-Serra said the results indicate that “The key ingredients for the origin of life could be present…” across other parts of the Milky Way as well. Researchers now hope to search for additional sugars, including ribose, which forms an essential part of RNA.
A Sweeter View of the Cosmos
The discovery does not prove that life exists elsewhere in the universe, but it shows that surprisingly complex chemistry can happen in the cold space between stars. Molecules connected to life may not be limited to planets or asteroids. They could be widely distributed throughout the galaxy.
As astronomers examine more molecular clouds with increasingly sensitive telescopes, they may uncover a larger collection of sugars and other organic compounds. Each discovery could bring scientists closer to understanding whether the chemical foundations of life are rare accidents or common features of the cosmos.
