Science

Astronomers detect first true sugar molecule in interstellar space

Researchers have identified erythrulose, a four-carbon sugar also present in raspberries, within a dense molecular cloud near the Milky Way's centre. The finding, grounded in matched telescope data and laboratory spectra, expands the known inventory of prebiotic compounds formed through natural processes in space.
Oscar Jones
20 Jul. 2026 · 11:51 3 min read Listen
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AI-generated image: Astronomers detect first true sugar molecule in interstellar space
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Intelligent summary
  • An international team using the Yebes and IRAM telescopes matched 12 spectral lines to confirm erythrulose in the molecular cloud G+0.693−0.027.
  • The four-carbon ketose sugar forms on dust grains at 20-30 kelvin and is at least eight times more abundant than undetected three-carbon analogues.
  • Researchers estimate 0.5 to 50 billion kilograms could have reached early Earth during the Late Heavy Bombardment, potentially contributing to prebiotic inventories.

The detection of a genuine sugar molecule floating in the cold expanse between stars opens a fresh window onto the chemical pathways that might once have seeded young planets. An international team led by researchers from Spain's Centre for Astrobiology has confirmed the presence of erythrulose in the molecular cloud G+0.693−0.027, some 26,700 light years from Earth near the galactic centre.

The identification rests on careful radio telescope observations. Data from the Yebes 40-metre and IRAM 30-metre telescopes, spanning more than 91 gigahertz across the 7-millimetre, 3-millimetre and 2-millimetre bands, yielded 12 spectral lines that matched laboratory spectra of erythrulose. This match establishes erythrulose as the first true sugar molecule verified in interstellar space.

Its abundance, roughly 6.4 × 10-10 relative to molecular hydrogen, is at least eight times higher than that of analogous three-carbon sugars, which the team's ultrasensitive observations failed to detect.

Erythrulose appears to be at least eight times more abundant than analogous three-carbon sugars, which remain undetected in our ultrasensitive observations.
said Izaskun Jiménez-Serra, lead researcher at the Center for Astrobiology.

Quantum chemical and astrochemical models show that erythrulose forms efficiently on the surfaces of interstellar dust grains. Simpler two-carbon aldehydes and alcohols react there at temperatures around 20 to 30 kelvin, building the four-carbon ketose through surface chemistry rather than gas-phase reactions. This mechanism fits the observed data without invoking exotic or untested assumptions.

As ketoses readily isomerise into aldoses under aqueous conditions, interstellar erythrulose could have added to the pool of sugars available for early metabolic and replication processes on a young Earth. The team estimates that between 0.5 × 109 and 50 × 109 kilograms of the molecule might have reached our planet during the Late Heavy Bombardment period, delivered by comets and asteroids that accreted material from the protosolar cloud.

interstellar chemistry prebiotic molecules erythrulose molecular clouds astrobiology
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