Alba Mons is considered Mars’ biggest volcano in terms of surface area. Also referred to as Alba Patera, it is larger even than the mighty Olympus Mons we’ve all heard about at one point in our lives.
Back in the day when it was active, Alba managed to spread its volcanic flow over an area of about 1,350 km (840 miles) around its summit, which is just 6.8 km (22,000 feet) above ground level - a height that's one-third that of the Olympus Mons. As per NASA, the structure of the volcano “has no counterpart on Earth,” making it the perfect subject for prolonged studies and observations.
What we have in the main image of this piece is not the entire volcano, though, but a portion of it that looks not unlike veins under a microscope. They’re not that, of course, but channels that “that seem to start at the margin of a lava flow,” according to the scientist from NASA and the University of Arizona.
The image before us is one of tens of thousands sent back over the years by the HiRISE camera circling planet on board the Mars Reconnaissance Orbiter, and was captured in the spring of last year from an altitude of 295 km (183 miles).
There is no mention of what the almost perfectly-round feature to the right of the channels might be.