# Why Aren't Earth Mountains Bigger Like Mars?

QUESTION:

"Mt Everest is just under 5.5miles high. Olympus Mons on Mars is 16 miles high. Why aren't there much larger mountains on Earth? What's the highest a mountain can go on Earth?" - David

Hello United States friend.

It's an intriguing cosmic comparison: Mount Everest, standing at just under 8.85 kilometres high, versus Olympus Mons on Mars, soaring to an impressive 25.75 kilometres.

The stark contrast begs the question: Why don't we see towering mountains like Olympus Mons on Earth? The answer lies in the forces of gravity, weight, and geology.

Gravity is a fundamental factor.

The gravitational pull on Earth is stronger than that on Mars. This difference in gravity significantly affects how tall mountains can grow on each planet.

As a mountain grows taller, its weight increases. This added weight can lead to two outcomes:

1. Crumbling Under Its Own Weight: Extremely tall mountains on Earth could eventually collapse under their own weight due to the force of gravity.

2. Sinking Back into Earth: The weight of a mountain can cause it to slowly sink back into the Earth's crust, a process known as isostatic subsidence.

Earth's gravitational force sets a theoretical maximum height for mountains of approximately 16 kilometres (about 10 miles). However, due to the way mountains form and the limitations of Earth's geology, reaching this maximum height is highly unlikely.

Interestingly, Mars' gravity is approximately 38% of Earth's gravity. By dividing Mount Everest's height of 8.85 kilometres by 0.38, we arrive at around 23.3 kilometres – a figure remarkably close to Olympus Mons' height. This demonstrates the influence of gravity on the potential height of mountains on both planets.

Gravity isn't the sole factor influencing mountain height. A significant consideration is how we measure elevation on Mars. Earth uses sea level as a reference point, whereas Mars lacks an equivalent sea level due to its absence of liquid water bodies. To establish a scientific reference, Mars' zero elevation datum was chosen to be the point where atmospheric pressure is at the triple point of water, approximately 610 pascals. In contrast, Earth's atmospheric pressure at sea level is about 101,000 pascals. Mars' lowest elevation is approximately 7.1 kilometres below Martian zero elevation, a smaller disparity than Earth's oceans are beneath sea level. Differences in elevation reference points lead to distinct measurements.

In essence, while the potent combination of gravity, weight, and geological processes dictates Earth's mountain heights, Mars showcases the effects of lower gravity and unique elevation reference points on Olympus Mons' grandeur. This comparison provides fascinating insights into the remarkable interplay between planetary physics and geological phenomena.

Also, the tallest mountain from the base on Earth is not Everest, but Mauna Kea at 10.0584 km from the ocean floor. Using your math, that gives us the Martian equivalent of 26.554176 km, making Earth better than Mars. Earth! Earth! Earth!

## ARSE Jnr

The section where we explain the above to 5-year-olds (and Flat Earthers).

Imagine you have some big building blocks, and you want to build a super tall tower. But there's something special about the Earth that makes it a bit tricky to build really, really tall mountains like the huge one on Mars called Olympus Mons.

You see, the Earth has something called gravity, which pulls everything down. It's like when you drop a ball, it falls to the ground. This gravity is stronger on Earth than on Mars. So, when we try to build super tall mountains on Earth, they can get very heavy, like a pile of toys that's too tall and starts to fall over.

Imagine you're stacking up lots and lots of blocks to make a mountain. If your mountain gets too heavy, it might break and fall down. That's what can happen on Earth if we try to make mountains super duper tall.

Also, the Earth's ground is like a bit squishy. So, if a mountain gets too heavy, it might start to sink into the squishy ground like a toy sinking into soft playdough.

Now, let's talk about Mars. Mars is a different planet, and its gravity isn't as strong as Earth's gravity. This means that on Mars, you can make really tall mountains without them getting too heavy and falling down.

Oh, and another thing: Earth has something called sea level, which is like the starting point for measuring how high things are. But Mars doesn't have oceans like Earth, so scientists needed to pick a different starting point. This can make measurements on Mars a little different.

So, while we have tall mountains on Earth, they can't be as super tall as the giant mountain on Mars, called Olympus Mons. That's because Earth's gravity and squishy ground make it a bit harder to build really, really tall mountains.

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