NASA’s SPHEREx Detects Organic Molecules in Interstellar Comet 3IATLAS

SPHEREx space TELESCOPE, a collaborative project between the United States (NASA) and South Korea, has just made new history.

Although its main task is to observe 450 million galaxies and 100 million stars to reveal the origins of the universe, this mission team took the time to observe the third interstellar object (ISO) ever detected in our solar system, namely comet 3I/ATLAS.

Through in-depth observations, the research team detected the presence of complex organic molecules such as water, carbon dioxide, carbon monoxide and cyanide. These molecules are widely recognized as the basic building blocks for the emergence of life. This finding provides a rare opportunity for scientists to directly examine the chemical composition of an alien planetary system without having to leave Earth.

Also read: Interstellar Comet 3I/ATLAS Stores Water and Organic Molecules, Revealed via the Korea–US Telescope

Changes in Comet Composition

3I/ATLAS was first discovered in July last year via NASA’s ATLAS survey telescope. Orbital analysis immediately confirmed that this comet came from outside the solar system. Along the way, researchers compared observation data from August with follow-up in December 2025.

Initially, this comet was dominated by carbon dioxide with little water content. However, as the comet approached the Sun, the chemical activity within it increased drastically.

This phenomenon occurs due to the sublimation process, where the ice on the comet’s surface turns directly into gas due to the heat of the Sun. Because heat takes time to penetrate into the comet’s nucleus, the most active emission of material occurs after the comet passes its closest point to the Sun (perihelion). This is what caused the brightness level and molecular diversity in 3I/ATLAS to increase significantly during December observations.

The Important Role of the SPHEREx Telescope

This success cannot be separated from SPHEREx’s position as a space telescope. Molecules such as water and carbon dioxide are very difficult to observe with telescopes on the Earth’s surface because the infrared light they emit is absorbed by our atmosphere. By being in space, SPHEREx is able to precisely capture specific infrared wavelengths to map the organic material emitted by the comet.

In the future, the research team will continue to collect additional data to compare the characteristics of comets from our solar system with interstellar comets. It is hoped that this long-term study will help scientists understand the process of forming exoplanet systems and how the materials that formed life were initially distributed in the universe. (Source: Universe Today, DongA Science/P-3)