While I’m in Chile climbing the mountain with the most superlatives in the world, I thought it might be interesting to consider just how superlative a mountain can get.
Most of us have climbed mountains where we’ve not been able to see the summit until we’re standing on it. A few of us have also climbed mountains where the slope has been so gentle that the horizon has remained just a few metres in front of us for much of the ascent (for me, Muztag Ata springs to mind).
But imagine climbing a mountain that’s so big, and the slope so gentle, that you have to keep walking for several days before the summit appears.
Such a mountain exists, but at the moment it’s a job getting there, because the mountain’s on Mars.
Mars’ Olympus Mons, the tallest known volcano in the solar system, has such a gradual slope that someone standing at the base couldn’t see the summit because it’s beyond the horizon. pic.twitter.com/cKjWpKGhIR
— Fermat’s Library (@fermatslibrary) December 13, 2018
This intriguing tweet contains a somewhat perplexing diagram. Not only does the mountain, Olympus Mons, appear to be half as high as the radius of a planet, but the little stick man appears to be nearly as high as the mountain.
To give a better idea of the scale of the giant volcano Olympus Mons, we need a better reference point. It’s over 21km high (compared to Everest’s 8.8km) and has an area of over 295,000 km2 (the size of Arizona or much of France).
Here is Olympus Mons compared to the state of Arizona (295,254 square km) pic.twitter.com/idgx4QH8Iu
— Brave Heart (@Brave_Heart07) December 13, 2018
But there’s more. Mars is a dry planet with no water (as far as we know). This means you can’t measure the height of a mountain from sea level like we do, because there isn’t any sea to measure from. Olympus Mons is therefore measured from its base, which raises another question. What would happen if we took away the sea – would 8,848m Everest still be the highest mountain on Earth?
The answer is no. Mauna Kea (4,205m) on the island of Hawaii rises straight out of one of the deepest parts of the Pacific Ocean. At 10.2km it would be marginally higher than Everest, but still less than half the height of Olympus Mons. It’s also slightly steeper: while Olympus Mons has a base width of 600km, Mauna’s Kea’s base width is only 250km
Measure Hawaii’s Mauna Kea volcano from the sea floor, and it’s taller than Everest. But Olympus Mons takes the cake. pic.twitter.com/J7MTX3cfDs
— Skunk Bear (@NPRskunkbear) June 26, 2015
But wait, there’s even more. With a height of 21km, Olympus Mons must be the highest mountain in the solar system, surely?
Olympus Mons isn’t even the highest mountain in the solar system. Apparently there’s a 529km-diameter asteroid flying around the solar system called Vesta, which has a 505km-diameter volcano on it called Rheasilvia.
My brain is currently exploding. How the hell do you measure the height of something that’s almost the same size as the thing it’s on? Cleverer people than me (people who are cunning enough to measure parts of an asteroid before it flies past them) claim that Rheasilvia is an incredible 22km high, narrowly pipping Olympus Mons to the title of highest mountain in the solar system. Or at least until some smart arse finds a bigger one.
So before I go back to climbing Ojos del Salado, the highest volcano on Planet Earth, here’s one more tweet with the diagram to end all diagrams.
— Rhys S-D (@Rhys_on_Earth) September 12, 2016
Thanks to Bob Schelfhout Aubertijn for spotting some of these tweets, and therefore giving me the idea for this post.