Astronomers have identified erythrulose, a four-carbon monosaccharide found in raspberries and self-tanning lotions, in the dense molecular cloud G+0.693-0.027, located roughly 26,700 light-years away near the centre of the Milky Way. The detection, published in Nature Astronomy, represents the first unambiguous sugar observed in the interstellar medium. Previous claims centred on glycolaldehyde, which chemists classify as a hydroxyaldehyde rather than a true saccharide. The signal was captured using the 40-metre Yebes and 30-metre IRAM radio telescopes in Spain and matched against laboratory-measured spectra.

The presence of erythrulose in a cold, star-forming cloud suggests that sugars can assemble on the icy surfaces of dust grains without the need for a planetary environment. Modelling indicates that simple organic fragments combine in frozen mantles, building complexity stepwise. Because the cloud is a site where new stars and planets will eventually form, the finding implies that key molecular components of RNA and DNA may be available from the earliest stages of planetary system formation.

Researchers at Spain’s Centro de Astrobiología led the study. Mark Sephton, a professor at Imperial College London, noted that the discovery reinforces the hypothesis that prebiotic compounds could have been delivered to the early Earth by comets and asteroids. Rebecca Allen of Swinburne University of Technology in Australia, who was not involved in the work, described the sugar as a potential clue to the origin of life’s building blocks. In a separate development, a team led by Harvard University reported in Science the first detection of an atmosphere around a rocky exoplanet in its star’s habitable zone. Observations of LHS 1140 b, a super-Earth discovered a decade ago, revealed escaping helium, confirming the presence of an atmosphere on a world where liquid water could exist.

The erythrulose detection opens a new observational window. The study’s authors are now targeting more biologically central sugars, such as ribose, using higher-sensitivity instruments and laboratory experiments that replicate interstellar conditions. For LHS 1140 b, the next milestone will be detailed atmospheric characterisation with next-generation space telescopes, which could identify molecular species and assess habitability more directly.