An international team of scientists has discovered traces of the rare isotope iron-60 in ancient Antarctic ice, providing what researchers describe as a direct record of the Solar System’s journey through interstellar space over tens of thousands of years.

The findings were published in Physical Review Letters and offer new insight into how material from ancient supernova explosions continues to surround and interact with our planetary system.

A Rare Isotope That Should Barely Exist on Earth

Iron-60 is a radioactive isotope that is extremely rare under natural conditions on Earth.

Scientists know it is produced almost exclusively during extreme cosmic events — especially supernova explosions. Because iron-60 has a half-life of roughly 2.6 million years, any detectable traces found on Earth today must have arrived from space relatively recently in astronomical terms.

Previous studies had already identified traces of the isotope in ocean sediments and modern Antarctic snow. But the new research looked much further back in time.

What Researchers Found in Antarctic Ice Cores

The team, led by researchers from Helmholtz-Zentrum Dresden-Rossendorf, analyzed nearly 300 kilograms of Antarctic ice core samples dating from 40,000 to 81,000 years ago.

Scientists melted the ice, extracted microscopic particles, and then carried out ultra-sensitive measurements to count individual iron-60 atoms.

The results showed isotope concentrations significantly higher than what could be explained by ordinary cosmic ray interactions alone. According to the researchers, this strongly points to material arriving from interstellar space.

The Solar System’s Journey Through a Cosmic Cloud

Researchers believe the discovery is linked to the Local Interstellar Cloud — a region of gas, dust, and plasma through which the Solar System is currently traveling.

The cloud is thought to have formed from the remnants of ancient supernova explosions and may still contain elevated amounts of iron-60 produced by those stellar deaths.

One particularly intriguing detail emerged from the timeline of the samples. Older ice layers contained lower concentrations of iron-60 than modern Antarctic snow.

That suggests the Solar System may gradually be moving from a less dense region of the cloud into an area richer in dust and heavy elements.

The researchers describe the Local Interstellar Cloud as a kind of cosmic archive preserving material forged in long-dead stars.

Why the Discovery Matters

The findings offer a rare way to study the Solar System’s movement through the galaxy using physical evidence preserved on Earth itself.

Rather than relying only on astronomical observations and computer simulations, scientists can now use Antarctic ice almost like a geological flight recorder tracking the changing interstellar environment surrounding the Solar System.

The research may also help astronomers better understand how nearby supernova explosions have influenced Earth’s cosmic environment over time.

In Brief

Scientists studying Antarctic ice up to 81,000 years old have discovered elevated levels of iron-60, a radioactive isotope produced mainly during supernova explosions.

The discovery suggests the Solar System has been traveling through the Local Interstellar Cloud — a region enriched with debris from ancient stellar explosions — for at least 80,000 years. Rising concentrations of the isotope over time may indicate that the Solar System is entering a denser part of the cloud, turning Antarctic ice into a remarkable archive of our cosmic journey through the galaxy.