Olympus Mons is How Tall?!

Olympus Mons is a big volcano. It is almost unimaginably huge. It is 550 kilometers (342 miles) across at its base, and the volcanic crater (the technical term is ‘caldera’) at the peak is 80 kilometers (53 miles) long. If you were standing at the edge of the caldera, the volcano is so broad and the slopes are so gradual that the base of the volcano would be beyond the horizon. That’s right, it is a volcano so big that it curves with the surface of the planet.

And it is tall. 27 kilometers tall. That’s 16.7 miles from base to summit. 88,600 feet. That’s about three times as tall as Mt. Everest. Even Mauna Kea, Earth’s own giant shield volcano doesn’t come close. Measured from the sea floor to its summit, Mauna Kea is 33,476 feet (10.2 km) tall: taller than Everest, but only about 40% the height of Olympus Mons.

The state of Hawaii, compered with Olympus Mons.

The state of Hawaii, compared with Olympus Mons.

Ok, so throwing those numbers around is fun if you like stats, but it still doesn’t convey quite how tall Olympus Mons is. So here’s an eye opener. Olympus Mons is so tall that it essentially sticks up out of Mars’s atmosphere. The atmosphere on Mars is thin to begin with, but at the summit of Olympus Mons, it is only 8% of the normal martian atmospheric pressure. That is equivalent to 0.047% of Earth’s pressure at sea level. It’s not quite sticking up into space, but it’s pretty darn close. In fact, it was first confirmed to be a huge mountain when Mariner 9 saw it towering above the top of a global dust storm like an island in a rust-colored sea.

Mariner 9 photograph of Olympus Mons towering above the clouds on Mars.

An airbrush painting of Olympus Mons towering above the clouds by Gorden Legg, a Hollywood artist, based on Viking Orbiter mosaic P17444.

Finally, since it is fun to compare Olympus Mons to Mauna Kea, what would the pressure be like at the summit if we placed Olympus Mons next to Mauna Kea in the Pacific? In that case, the summit of Olympus would be 21 km (68,897 ft) above sea level: still higher than Everest, and about twice as high as normal jets fly. The atmospheric pressure at the summit would be about 4.6% that at sea level. For comparison, at the top of Everest it is about one third the pressure at sea level, and most people still need to use oxygen canisters.

Olympus Mons is huge. Hopefully these numbers give you a little better idea of just how huge. If you’re wondering how it got to be so big, I already wrote about that in this post about shield volcanoes, so go check it out!

The tallest mountains on Mars, Earth, and Venus compared. Note that the horizontal scale is drastically squashed.

The tallest mountains on Mars, Earth, and Venus compared. Note that the horizontal scale is drastically squashed.

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20 Comments on “Olympus Mons is How Tall?!”

  1. Duncan Young Says:

    The above image allegedly from Mariner 9 would hard for the hardy little orbiter to generate, as the color filter wheels failed as the global dust storm was receding. I was intrigued, so I went a’googling for the source of this image, which comes up a lot. LPI has the answer – it was an airbrush painting by Gorden Legg, a Hollywood artist, based on Viking Orbiter mosaic P17444 link , commissioned for a NASA movie on Viking and found the cover of NASA Special Publication 444 “Images of Mars: the Viking Extended Mission”.

    An actual picture of Nix Olympus, as it was known, emerging from the murk can be found here.

    Another note: if you scale for gravity, Olympus Mons is about the same height as Hawaii. Both of course pale in comparison to the largest volcanic system in the solar system: Earth mid-oceanic ridges, which over the course of less than 100 million years generated at least 2/3’s of Earth’s crustal area, and wrap around the planet.

    • Ryan Says:

      Oops, I realized while I was writing that that image couldn’t be from Mariner 9, but apparently forgot to fix the caption. Thanks for digging up the info, I’ll fix it now!


    • At some point in Earth’s history, the mid oceanic ridges may have generated that quantity in the course of 100 million years, but the existing mid-oceanic ridges did not generate 2/3rds of the Earth’s existing crust in the last 100 million years.

  2. Kevin Says:

    I’m currently reading Red Mars and I have a new/better appreciation for pretty much everything Martian. Vague spoiler follows: The party on Olympus Mons and the surrounding descriptions of the mountain are what I’m thinking of here.

    On a side note: Reading Red Mars and thinking about the base on Phobos made me realize how cool being in different gravity would be… Where are the moon hotels!

    • Ryan Says:

      I just started re-reading it. Is the map in your book backwards, because it is in mine! The words are correct, but the geography is flipped east-west. I remember being really confused by the map back when I first read it, and now I see why!

  3. barry Says:

    Fantastic….and they say that their couldnt be life on other planets..

  4. bob yjy Says:

    What is the Logitude and latiude of olympus mons


  5. that is big montin there man you guy rock for finding it.


  6. Tingginya gunung ni.Ingatkan Everest yang paling tinggi wou…………………….

  7. Bryan M. Says:

    I can’t belive how tall it is!

  8. Connor Stark Says:

    I bet there was living life on mars millions of years ago… why would god only make us?

    • fh100 Says:

      Because Connor ..The Bible tells us so!!!!Here we go again religious nutters will now say that any life or remnants of life discovered proves there must exist a christian God.As evidence of life being created not only once but twice doubles the possibility that their must of been a creator….Honestly Connor!!!!!


  9. [...] Mount Everest but Olympus Mons is three times as high! The Martian Chronicles ask the question and provide facts to get [...]

  10. buckeye Says:

    wow?!?!?!? that is amazing

  11. Space Tycoon Says:

    Good thing I’m “inside” Olympus Mons. Now I’m going to search for the ancient conduit that’ll show me where the center of Mars is. Then I’m going to laser it and clear the conduit so I can throw all the iron on the surface of Mars, along with some gasoline and create a huge inferno to rekindle the geodynamo. I aim my laser at the gasoline to ignite it. Wish me luck.
    (we need to throw the iron that’s on the surface of Mars, back into the conduit so that it melts and falls toward the center of Mars. Remember the immense pressure at the center of a globe will solidify the iron, creating a solid iron core.

  12. Space Tycoon Says:

    There’s an estimated 40 trillion tons of Uranium and 120 trillion tons of Thorium in the Earth’s crust.

    Uranium 238 has a half life of 4.468 billion years! That means if we rekindle Mars’ geodynamo by throwing in U238, it’ll last until the Sun dies out. U-238 also creates the much´╗┐ needed “convection” necessary to create and maintain a geodynamo. Mars is a perfect candidate for a geodynamo since it spins on its axis in much the same way Earth does. There are 3 requirements for a geodynamo: molten metals (especially iron/nickel/cobalt); rotation; and convection. Uranium 238 would also be required to keep the geodynamo going for the next 4.5 billion years. It should be dropped near the mantle.

  13. Katie Daly Says:

    Totally loving this! I’m in the middle of writing an essay and abstract about Olympus Mons, and this has been really useful!!


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