Mercury's Bright Streaks Hint at Ongoing Geological Activity

Recent models indicate that bright streaks, formally known as lineae, observed on Mercury's surface are likely signs of recent geological activity. This challenges previous assumptions that Mercury was geologically inactive.

Astronomer Valentin Bickel from the University of Bern, Germany, and colleagues from the Astronomical Observatory of Padova, Italy, surveyed 402 such streaks. Their research suggests Mercury's surface is more volatile than previously believed, despite the planet's lack of atmosphere and 4.5 billion years of cooling.

Unveiling Mercury's Volatility

The team utilized machine learning to analyze 100,000 high-resolution images of Mercury taken between 2011 and 2015. Findings show that these bright lines tend to cluster on the sun-facing slopes of craters. While they do not always appear to originate from hollows, most streaks do.

Given that lineae on other planets are believed to erode quickly, the study authors hypothesize that these streaks are still forming and evolving on Mercury today.

This suggests an ongoing mercurial present driven by the flow of heat and volatile materials, such as sulfur, from beneath the planet's surface.

The Role of Volatile Materials

According to Bickel, volatile material could reach the surface through networks of cracks in the rock caused by impacts. The depressions known as 'hollows,' from which most streaks originate, are also thought to be formed by the outgassing of volatile material, typically located within or along the edges of large impact craters.

The research team plans to validate their hypothesis with new images of Mercury from missions conducted by the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA). The study was published in Nature Communications Earth & Environment.