A new study proposes that some of Earth’s largest geological and biological upheavals may follow a roughly 27-million-year cycle, potentially linked to the solar system’s motion through the Milky Way.

The research, led by geologist Professor Michael Rampino of New York University and published in the journal Evolving Earth, argues that mass extinctions, large volcanic eruptions, asteroid impacts, and other major geological events appear to cluster in recurring intervals.

However, the hypothesis remains debated within the scientific community. Many researchers question whether the apparent pattern is statistically robust and whether any causal connection between Earth’s geology and the solar system’s movement through the galaxy has been demonstrated.

What Does the Study Claim?

Professor Michael Rampino analysed geological records spanning approximately the last 260 million years.

According to the study, several categories of major events appear to occur in recurring patterns, including:

• Mass extinction events.
• Large asteroid impacts.
• Massive volcanic eruptions.
• Significant changes in sea level.
• Ocean oxygen depletion (ocean anoxia).
• Variations in seafloor spreading.
• Major tectonic activity.

The analysis suggests many of these events cluster around intervals of approximately 27 million years.

Rampino also proposes additional cycles of roughly 9 million years and about 250–270 million years, although the 27-million-year interval is the primary focus of the study.

Does This Mean Earth Is ‘Due’ for Another Mass Extinction?

Not necessarily.

Although the study identifies a recurring pattern, the presence of a statistical cycle does not establish that another catastrophic event is imminent.

Numerous interacting factors influence Earth’s geological and biological systems, and scientists cannot currently predict future mass extinctions based on a repeating timetable.

The study should therefore be viewed as a hypothesis about long-term geological patterns rather than a forecast of future disasters.

How Could the Milky Way Be Involved?

One part of the hypothesis concerns the Solar System’s motion through the Milky Way.

As the Sun orbits the center of the galaxy, it also moves above and below the Milky Way’s galactic plane, crossing it periodically over tens of millions of years.

Some researchers have proposed that these crossings could gravitationally disturb the distant Oort Cloud—a vast reservoir of icy objects surrounding the Solar System.

If enough objects are disturbed, the number of comets entering the inner Solar System could temporarily increase, potentially raising the likelihood of impacts on Earth.

This idea has been explored in previous scientific studies, although evidence for a direct connection remains inconclusive.

What About Earth’s Interior?

Rampino also argues that periodic changes may originate within Earth itself.

The planet’s mantle slowly circulates over millions of years, driving plate tectonics and volcanic activity.

According to the study, changes in these deep-Earth processes could contribute to episodes of:

• Large-scale volcanism.
• Earthquakes.
• Continental rearrangement.
• Environmental changes capable of affecting life on Earth.

The study suggests these internal processes may coincide with longer astronomical cycles.

What Is the Dark Matter Hypothesis?

One of the study’s most speculative proposals involves dark matter.

Rampino suggests that during certain phases of the solar system’s journey through the galaxy, Earth could encounter regions with higher concentrations of dark matter.

According to the hypothesis, dark matter particles could accumulate within Earth’s interior and release additional heat under specific theoretical conditions, potentially influencing geological activity.

However, there is currently no direct observational evidence that this process occurs.

Dark matter itself has not yet been directly detected in laboratory experiments, and its interactions with ordinary matter remain one of modern physics’ biggest unanswered questions.

Why Is the Study Controversial?

Scientists have debated periodic extinction hypotheses for decades.

Critics argue that:

• Geological dating carries uncertainties that make precise cycles difficult to establish.
• Apparent patterns may arise through statistical chance.
• Different extinction and geological datasets do not always produce the same periodicity.
• No single physical mechanism has been conclusively shown to link galactic motion with Earth’s geological history.

Rampino acknowledges these limitations and notes that his interpretation remains one possible explanation rather than an established conclusion.

Why This Research Matters

Understanding whether Earth’s largest environmental crises follow long-term patterns could improve scientists’ understanding of both planetary evolution and the history of life.

Even if the proposed mechanisms ultimately prove incorrect, studies like this encourage researchers to examine connections between:

• Earth’s internal geology.
• Climate history.
• Asteroid impacts.
• Galactic dynamics.
• Biological evolution over hundreds of millions of years.

Future geological records, astronomical observations, and improved dating techniques may help determine whether the proposed 27-million-year cycle reflects a genuine natural rhythm or a statistical coincidence.

The Bottom Line

A new study suggests that Earth’s major extinction events and geological upheavals may recur in a roughly 27-million-year cycle linked to both deep-Earth processes and the Solar System’s journey through the Milky Way. While the hypothesis is supported by pattern analysis presented by the study’s author, many of its proposed mechanisms—including links to galactic motion and dark matter—remain speculative and are not part of the current scientific consensus. Further research will be needed to determine whether the apparent cycle represents a genuine feature of Earth’s history.

TL;DR

• A new study proposes that major geological and extinction events recur roughly every 27 million years.
• The research links these events to Earth’s geological processes and the Solar System’s movement through the Milky Way.
• The study also explores possible roles for comet disturbances and hypothetical dark matter interactions.
• These proposed mechanisms remain speculative and have not been established as scientific consensus.
• The author acknowledges that the hypothesis is controversial and requires further evidence.