Painted Planet: Mercury's Surface May Be Darkened by Comet Dust

The dark surface of Mercury may have an unusual origin: a billion-year paint job by passing comets. "It's long been hypothesized that there's a mystery darkening agent that's contributing to Mercury's low reflectance," said Lawrence Livermore National Laboratory's Megan Bruck Syal, co-author of a study published in Nature Geoscience. "One thing that hadn't been considered was that Mercury gets dumped on by a lot of material derived from comets."

Such cosmic passersby would likely start to break up that close to the sun, shedding a great deal of carbon into the neighborhood. Over billions of years, that constant bombardment would render the surface of Mercury as much as 3 percent to 6 percent carbon by weight. The comet chunks would also impact at great speed — the researchers tested the result of this using the NASA Ames Vertical Gun Range, a special cannon that can fire objects at stellar velocities (as much as 16,000 mph) to simulate events like meteorite strikes. They found that simulated comet pieces produced a thin coating of embedded carbon that absorbed light much the way Mercury's surface does.

For Subscribers

FOR SUBSCRIBERSAbdul El-Sayed tries to woo MAHA voters as Democrats seek inroads with RFK’s supporters

FOR SUBSCRIBERSKratom-like substances are popping up in a typically benign supplement

FOR SUBSCRIBERSGOP super PAC increases its spending for Sen. Jon Husted in tough Ohio race

FOR SUBSCRIBERSRecords reveal tumultuous marriage between slain New York Times executive and wife

FOR SUBSCRIBERSFrom clean energy warrior to ‘wall of shame,’ James Talarico reverses on a fossil fuel money pledge

FOR SUBSCRIBERSCongressional staff planned official trip with luxury stops in Italy and France weeks before election

FOR SUBSCRIBERSA harrowing ordeal aboard an Israel-bound plane

FOR SUBSCRIBERSOpenAI CEO Sam Altman to skip congressional hearing on rogue AI agents

FOR SUBSCRIBERSKey DOJ lawyers departed Trump ‘grand conspiracy’ probe amid pressure to produce, source says

FOR SUBSCRIBERSTrump’s new AI chatbot often links to a site launched under Clinton 26 years ago

FOR SUBSCRIBERSAt MAHA summit, industry CEOs the movement once vilified take the stage

FOR SUBSCRIBERSThis Paralympian has two goals: Win medals and give away $500,000 to her teammates

FOR SUBSCRIBERSCornell rape allegation spotlights stringent New York state laws that have long drawn criticism

FOR SUBSCRIBERSThe debate over AI’s future rages on both coasts

FOR SUBSCRIBERSDecades-old march dispute reignites in Northern Ireland, threatening political crisis

For Subscribers

FOR SUBSCRIBERSAbdul El-Sayed tries to woo MAHA voters as Democrats seek inroads with RFK’s supporters

FOR SUBSCRIBERSKratom-like substances are popping up in a typically benign supplement

FOR SUBSCRIBERSGOP super PAC increases its spending for Sen. Jon Husted in tough Ohio race

FOR SUBSCRIBERSRecords reveal tumultuous marriage between slain New York Times executive and wife

FOR SUBSCRIBERSFrom clean energy warrior to ‘wall of shame,’ James Talarico reverses on a fossil fuel money pledge

FOR SUBSCRIBERSCongressional staff planned official trip with luxury stops in Italy and France weeks before election

FOR SUBSCRIBERSA harrowing ordeal aboard an Israel-bound plane

FOR SUBSCRIBERSOpenAI CEO Sam Altman to skip congressional hearing on rogue AI agents

FOR SUBSCRIBERSKey DOJ lawyers departed Trump ‘grand conspiracy’ probe amid pressure to produce, source says

FOR SUBSCRIBERSTrump’s new AI chatbot often links to a site launched under Clinton 26 years ago

FOR SUBSCRIBERSAt MAHA summit, industry CEOs the movement once vilified take the stage

FOR SUBSCRIBERSThis Paralympian has two goals: Win medals and give away $500,000 to her teammates

FOR SUBSCRIBERSCornell rape allegation spotlights stringent New York state laws that have long drawn criticism

FOR SUBSCRIBERSThe debate over AI’s future rages on both coasts

FOR SUBSCRIBERSDecades-old march dispute reignites in Northern Ireland, threatening political crisis

A planetwide layer of this could very well be the source of Mercury's darkness, said co-author Peter Schulz of Brown University: "It appears that Mercury may well be a painted planet."

• Add to Google

Ice flourishes on planet near Sun

00:36

IN-DEPTH

• Mars Curiosity Rover Spots Mercury Crossing the Sun
• Mercury is Shrinking, Wrinkling New Maps Show
• Goodnight, Moon: Messenger Probe Tracks Lunar Eclipse From Mercury

SOCIAL

-- Devin Coldewey