The smallest planet in our solar system (sincere apologies, Pluto), has comet dust as a source for its dark appearance. Mercury indeed has curious coloring since it appears much darker than it should, which left scientists puzzled. But a new study published in Nature Geoscience suggests a new theory for the phenomenon.
Since Mercury practically has no atmosphere and is the nearest planet to the sun, where space debris impacts are usual and solar winds are quite violent it is expected to acquire a lot of tiny iron particles which have the property of absorbing light and make planets look darker.
By launching sugary missiles at a target that simulates the darker areas of the surface of moon, the study authors demonstrates that comet carbon has really powerful sticking power. The heat of impact made the tiny particles of carbon to break, which then embedded into the melted impact crater of their new home. Experiments show that impact material darkens even more when impacts take place in the presence of complex organics.
The impact spots then absorbed a lot more light than they had before. Only 5 percent of light shown on those spots was reflected. But the carbon didn’t reveal itself in spectral analysis, which could explain why similar readings on Mercury haven’t revealed the cosmic paint job.
“We show that carbon acts like a stealth darkening agent,” study co-author Peter Schultz, professor emeritus of geological sciences at Brown, said in a statement. “From the standpoint of spectral analysis, it’s like an invisible paint.”