NASA’s SPHEREx Telescope Reveals New Clues About Interstellar Comet 3I/ATLAS

NASA’s SPHEREx space telescope has delivered new insights into interstellar comet 3I/ATLAS, only the third such object ever observed passing through the solar system. Observations made in December 2025 revealed a rich mix of organic molecules and heightened cometary activity, strengthening scientific understanding of material formed beyond the Sun’s influence.

The findings provide valuable clues about the chemical composition and physical processes operating in distant planetary systems.

---

SPHEREx Telescope: Infrared Observations of a Rare Interstellar Visitor

The SPHEREx mission of the National Aeronautics and Space Administration turned its advanced infrared instruments toward comet 3I/ATLAS shortly after it passed closest to the Sun.

Key Molecular Detections:

• Methanol
• Cyanide
• Methane

These organic molecules are fundamental to biological processes on Earth. However, scientists emphasise that such compounds can also form through non-biological chemical reactions in space, indicating that complex chemistry is widespread in the universe.

Infrared observations are crucial because they allow scientists to study cold, dust-covered objects that are invisible in visible light.

---

Post-Perihelion Brightening and Cometary Activity

Mission scientists reported a dramatic increase in the comet’s brightness nearly two months after its closest approach to the Sun (perihelion).

Reason Behind the Delayed Brightening:

This phenomenon is linked to sublimation, in which frozen ices directly convert into gas as solar heat penetrates deeper layers of the comet.

As gases escape, they form a surrounding atmosphere called the coma, which was found to be rich in:

• Water vapour
• Carbon dioxide
• Carbon monoxide

The expanding coma reflects sunlight and increases brightness, making the comet more visible from Earth.

---

Evidence of Pristine Subsurface Material

According to the research team, the delayed venting indicates that deep, previously unexposed ices began erupting well after peak solar heating.

Major Scientific Observations:

• Release of carbon-rich material locked beneath the surface for billions of years
• Presence of soot and rocky dust
• Detection of large solid fragments

These features suggest that 3I/ATLAS is ejecting heavier and more primitive material than typically observed in solar system comets, offering a rare glimpse into the untouched building blocks of other star systems.

---

Scientific Significance of the Discovery

Interstellar comets like 3I/ATLAS are considered natural probes of distant planetary systems, as they originate outside the Sun’s gravitational influence.

Why This Discovery Matters:

• Helps study chemical processes beyond the solar system
• Improves understanding of planetary formation
• Supports research on the origins of organic molecules
• Enhances models of comet evolution
• Contributes to astrobiology and cosmic chemistry

The findings suggest that complex organic chemistry may be common across the galaxy, strengthening the possibility of life-friendly environments elsewhere.

---

Conclusion

The SPHEREx observations of interstellar comet 3I/ATLAS represent a major advance in understanding material formed beyond the solar system. By detecting organic molecules and revealing delayed subsurface activity, the mission has provided rare insights into pristine cosmic matter preserved for billions of years. These discoveries reinforce the role of space-based infrared astronomy in unlocking the chemical history of the universe and deepening humanity’s understanding of its cosmic origins.

---

---

---