Mars's "Aurora Universalis": How the Same Physics That Creates the Northern Lights Drives a Global Light Show on the Red Planet

The Central Discovery: A Miniature Dungey Cycle on Mars

The Dungey cycle is the engine behind Earth's auroras. It describes how the solar wind's magnetic field lines connect—or "reconnect"—with a planet's magnetic field, accelerating charged particles along magnetic field lines down into the atmosphere. On Earth, this happens on a global scale because our planet has a strong, planet-wide magnetic field that funnels particles toward the poles .

MAVEN found that the same fundamental process occurs on Mars, but only over localized patches of strong crustal magnetic fields in the southern highlands . These fields are the frozen-in remnants of Mars's ancient global dynamo, which died billions of years ago. The crustal fields act like localized magnetic umbrellas, sprouting out of the ground and interacting with the solar wind .

Crucially, the study showed that protons, not electrons, are the dominant driver of many Martian auroras . Here is how it works:

1. Solar wind protons (hydrogen ions) approach Mars.
2. They capture electrons from neutral hydrogen atoms in Mars's extended hydrogen exosphere, becoming neutral hydrogen atoms themselves .
3. Because they are neutral, these atoms are no longer blocked by Mars's bow shock or ionosphere. They can plunge deep into the atmosphere.
4. Once inside, they re-ionize (lose their stolen electrons) and collide with atmospheric gases. The resulting glow—primarily in ultraviolet light—is the Martian aurora .

MAVEN also observed a second type of aurora: patchy proton aurora, which forms when turbulent solar wind conditions allow charged protons to stream directly into the Martian atmosphere . During powerful solar storms, the spacecraft detected diffuse nightside aurora triggered by solar energetic particles that bypass the bow shock entirely .

Comparison: How Martian Auroras Differ from Earth's Northern Lights

While the underlying physics is the same, the expression of that physics on the two planets is starkly different. The table below summarizes the key comparisons.

In short, as Science magazine noted, Mars experiences what scientists have called “aurora universalis”—auroras that are not tied to the poles but can cover much of the planet's face .

The Evidence: Instruments That Confirmed the Findings

MAVEN was equipped with a suite of instruments designed to study the Martian upper atmosphere and its interaction with the solar wind. The primary instrument for auroral detection was the Imaging Ultraviolet Spectrograph (IUVS) . IUVS scanned the planet in ultraviolet light, specifically detecting Lyman-alpha emission from hydrogen, which is the primary signal of proton aurora.

Supporting instruments that provided the broader context included:

• Solar Wind Ion Analyzer (SWIA) and Solar Wind Electron Analyzer (SWEA) — These measured the energy and flux of incoming solar wind particles, providing the direct evidence of proton entry into the atmosphere .
• Magnetometer (MAG) — Mapped the topology of the crustal magnetic fields, confirming exactly where the field lines were guiding the solar wind particles .
• Neutral Gas and Ion Mass Spectrometer (NGIMS) — Measured changes in atmospheric composition during auroral events .

The initial discovery of a widespread, diffuse aurora on Mars occurred in December 2014, when MAVEN's IUVS detected a bright ultraviolet glow spanning the northern hemisphere for five days. Scientists called it the “Christmas lights” event. This was followed by the 2018 discovery of proton aurora, which correlated IUVS hydrogen emission data with SWIA measurements of proton flux .

Publication Details and Broader Implications

The landmark study that connected the dots and confirmed the Dungey cycle as the driving mechanism was published on July 24, 2026 in the journal Nature Communications. The paper is titled “Miniature Dungey-like cycle drives aurora at Mars” and was authored by Shaosui Xu and colleagues .

This finding has implications that go far beyond pretty lights:

• Planetary Magnetic Evolution: It helps explain how Mars, despite losing its global planetary dynamo billions of years ago, still actively interacts with the solar wind. The crustal fields are a ghost of a magnetic past, and the Dungey cycle shows that even ghostly magnetic fields can shape a planet's atmosphere .
• Atmospheric Escape: Magnetic reconnection is not just about auroras; it also accelerates atmospheric ions into space. MAVEN data revealed that this process, called atmospheric erosion, escalates dramatically during solar storms. This finding has been crucial in quantifying how Mars lost most of its atmosphere—and its water—over geologic time .
• Comparative Planetology: Confirming that the Dungey cycle operates on another terrestrial planet, but scaled down and localized, validates our understanding of magnetic reconnection as a universal plasma physics process .

The Final Chapter: The End of the MAVEN Mission

After more than 11 years in orbit—a full decade beyond its planned one-year primary mission—MAVEN's operational life came to an end. NASA lost contact with the spacecraft on December 6, 2025, when MAVEN experienced an unexpected loss of attitude control as it was emerging from behind Mars . An anomaly review board determined that the spacecraft had begun to rotate unexpectedly, rapidly depleting its battery power .

After months of recovery attempts using the Deep Space Network and the Green Bank Observatory , NASA officially declared the mission over on June 3, 2026, citing an “unrecoverable state” . At the time of its loss, MAVEN had completed 10+ years of science operations, mapped atmospheric escape across an entire solar cycle, discovered multiple types of Martian aurora, and served as a critical communications relay for rovers on the surface .