Every good story deserves a sequel – and the strange white cloud spotted above an extinct Martian volcano back in 2018 just got one, because the stunning fog trail has made another appearance.
In fact, this is the latest instalment in a long-running series, and this time scientists were looking out expectantly for the event.
It’s thought that the white plume is formed from dense air near the planet’s surface getting forced uphill, where the temperature drops and the moisture condenses around dust particles.
It happens on Earth too: it’s called orographic lift.
So this doesn’t mean the long-dead Arsia Mons volcano is suddenly bursting back into life. But even though the cloud isn’t associated with volcanic activity, it’s still a stunning sight to behold.
“We have been investigating this intriguing phenomenon and were expecting to see such a cloud form around now,” says physicist Jorge Hernandez-Bernal, from the University of the Basque Country in Spain.
“This elongated cloud forms every Martian year during this season around the southern solstice, and repeats for 80 days or even more, following a rapid daily cycle. However, we don’t know yet if the clouds are always quite this impressive.”
Hernandez-Bernal is part of a team using the Visual Monitoring Camera (VMC) on the Mars Express probe to…