Discovery of Interstellar Comet 3I/ATLAS

In an exciting discovery, the Deep Random Telescope in Chile, part of the ATLAS project (Asteroid Terrestrial-impact Last Alert System), detected a new comet on July 1, 2025. However, this was not just any ordinary comet; it is not gravitationally bound to the Sun, indicating that it originated outside our solar system.

Characteristics of Comet 3I/ATLAS

Comet 3I/ATLAS is the third known interstellar object to enter our solar system and is the largest and brightest to date. Its discovery has provided researchers worldwide with a unique opportunity to study this extraordinary celestial body using all available tools, including NASA’s new space observatory, SPHEREx.

Observations from SPHEREx revealed large amounts of carbon dioxide gas in the comet’s hazy coma, as well as water ice in its nucleus. This discovery marks a significant step in understanding how comets from other star systems compare to those formed in our solar neighborhood.

Using SPHEREx to Study the Comet

SPHEREx, which stands for “Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer,” is a powerful tool for studying comets. Scientists found that the comet contains large amounts of vaporized carbon dioxide, suggesting similarities to ordinary solar comets.

Comets are composed of rocky dust, water, carbon dioxide, and carbon monoxide, the three most abundant materials in our solar system. The amount of each element depends on the time and place of the comet’s formation and its subsequent evolution.

The Scientific Importance of SPHEREx’s Discovery

Olivier Doré, the scientist leading the SPHEREx project at NASA’s Jet Propulsion Laboratory, explained the broader impact of the mission. By mapping the entire sky in 102 colors, we can study all kinds of celestial bodies, from distant galaxies and nearby stars in the Milky Way to comets in our solar system, whether they are interstellar visitors or not.

This highlights the transformative power of the dataset we are now generating. The richness of the information is exceptional and will fuel discoveries across the astronomical community as our data is continuously released.

Conclusion

Comet 3I/ATLAS is an exciting discovery that opens a new door to understanding interstellar comets and how they form and evolve. With the advanced technologies provided by SPHEREx, scientists can now study these celestial bodies in ways that were not possible before, enhancing our knowledge of the solar system and the universe as a whole. As the comet continues to be monitored and approaches the Sun, it is expected to provide more valuable information about its characteristics and composition.