If it looks like a volcanic eruption and acts like a volcanic eruption, is it a volcanic eruption … even if it’s on Mars, which hasn’t had an eruption at this particular volcano in at least 50 million years and hasn’t had a lava flow anywhere in at least 2 million years? That question is currently being hotly debated by astronomers and conspiracy theorists after many people looking at recent pictures from the European Space Agency's Mars webcam on board its Mars Express orbiter spotted what looks like a volcanic plume over Arsia Mons, a volcano on the Tharsis bulge near the Martian equator. Is it a volcano or is it something else? Is it being covered up or is it something else?
Let’s start by saying that no one questions that something DID happen on Mars over the Arsia Mons volcano and it WAS photographed by the webcam on the ESA’s Mars Express orbiter. The pictures being referenced appear to be from 9-5-2018 to 10-20-2018. Further investigation by Forbes found that NASA’s 2001 Mars Odyssey mission also picked up clouds over Arsia Mons in September 2018. Those photos didn’t cause the same controversy in the conspiracy community since the looked more like fog than a volcanic plume.
Speaking of the conspiracy community, multiple sites picked up the photographs, called it a volcanic eruption and speculated it was being covered up with their evidence being the recent shutdown of the solar observatory in New Mexico, shutdowns of other observatories and the conspiracy theorists' inherent distrust of NASA. Those shutdowns have been explained (the one in New Mexico was due to a criminal investigation and possible threats) and one wonders why a ‘solar’ observatory would be shut down over a Martian eruption. The answer is point three – they don’t trust NASA.
For those who do trust NASA, at least occasionally, it sent Tanya Harrison, Director of Research for Arizona State University's Space Technology and Science Initiative and a Science Team Collaborator on the Mars Exploration Rover (MER) Opportunity, to Twitter to explain the plume.
"It's not a plume of smoke, but rather water ice clouds condensing out over the summit of the Arsia Mons volcano. We see them quite often over this particular volcano."
She also showed another view of the Arsia Mons from the Mars Reconnaissance Orbiter in October showing ice clouds and explained further:
“We see these clouds hang out over the summit of Arsia for weeks at a time during this time of year, every year. It's a combination of its high elevation and the amount of water vapour in the atmosphere at this time of year causing the clouds to form.”
A report about the plume in Forbes agrees with Harrison, referencing similar plumes in 2015 and a 2005 study in the Journal of Geophysical Research about “persistent water ice clouds on the flanks of Arsia Mons Volcano.” Jacob Richardson, a postdoctoral researcher at NASA’s Goddard Space Flight Center, gives the accepted volcanic history of Arsia Mons in a 2017 study:
“We estimate that the peak activity for the volcanic field at the summit of Arsia Mons probably occurred approximately 150 million years ago—the late Jurassic period on Earth—and then died out around the same time as Earth’s dinosaurs. It’s possible, though, that the last volcanic vent or two might have been active in the past 50 million years, which is very recent in geological terms.”
And yet … the distrust of all things NASA leads to the current questioning of all things Arsia Mons. Perhaps the real question we should be asking is this: if this truly is the first recorded volcanic eruption on Mars in 50 million years, wouldn’t NASA and the ESA be shouting just as loudly … not to mention fighting over whose discovery it was?