Olympus Mons

Olympus Mons is a huge shield volcano on Mars. It stands about 21 kilometers high, which is more than two and a half times taller than Mount Everest, the highest mountain on Earth. This makes it the tallest mountain we know of in our whole Solar System.

This amazing volcano is part of a region called Tharsis Montes and last erupted around 25 million years ago. People have known about Olympus Mons since the late 1800s, when they saw something bright on Mars that they called "Olympic Snow." Later, space probes showed that it was indeed a massive mountain.

Scientists have given names to two big craters on Olympus Mons. These craters might be where some meteorites from Mars, called shergottites, come from. Studying Olympus Mons helps us learn more about volcanoes and how mountains form on other planets.

Description

Olympus Mons is a huge volcano on Mars. It is the tallest mountain in our solar system, standing about 22 kilometres high — that’s almost three times taller than Mount Everest on Earth! This giant volcano is wide too, about as big as the country of Italy. Olympus Mons looks like the big volcanoes in the Hawaiian Islands, with gentle slopes that spread out far from its peak.

Because Mars doesn’t have moving tectonic plates like Earth, Olympus Mons was able to grow very large over time. Its top has several wide, shallow craters, and its edges rise sharply in cliffs. Even though the air is very thin up there, clouds and dust still move over the mountain’s summit.

Geology

Olympus Mons is a huge volcano on Mars made from many layers of lava that flowed from its top over millions of years. It looks similar to the volcanoes in the Hawaiian Islands, but much larger. Because Mars has less gravity than Earth, the lava could flow farther and build up higher mountains.

The top of Olympus Mons has several large craters called calderas, formed when the magma underneath drained away after eruptions. Scientists think the magma chambers for these calderas lie deep below the surface. The shape of the volcano is not perfectly round; one side is steeper and more rugged than the other, likely because of how the ground moved as the volcano grew.

Early observations and naming

Olympus Mons and some other volcanoes in the Tharsis area are so tall that they rise above the dust storms that often cover Mars. As early as the 1800s, people watching Mars through telescopes noticed that during these storms, only a few features—like Olympus Mons—could still be seen. They guessed these must be very high.

Later, the Mariner 9 spacecraft reached Mars in 1971 during a big dust storm. When the dust cleared, the tops of the Tharsis volcanoes were the first things seen. This showed they were much taller than any mountain on Earth. These observations helped scientists confirm that Nix Olympica was a volcano, and they officially named it Olympus Mons.

Regional setting and surrounding features

Olympus Mons is found between the northwestern edge of the Tharsis region and the eastern edge of Amazonis Planitia. It lies about 1,200 km from three other large volcanoes on Mars, called the Tharsis Montes (Arsia Mons, Pavonis Mons, and Ascraeus Mons). These volcanoes are a bit smaller than Olympus Mons.

A wide, circular valley about 2 km deep surrounds the base of Olympus Mons. This valley likely formed because the weight of the volcano pressed down on Mars's surface. The valley is deeper on the northwest side than on the southeast side. Around Olympus Mons, there is a special area of bumpy land called the Olympus Mons aureole. This area has several large sections. To the northwest, it stretches up to 750 km and is called Lycus Sulci. To the east, the aureole is sometimes covered by lava flows, but where it is visible, it has different names like Gigas Sulci. Scientists think the aureole was formed by big landslides or movements of rock caused by gravity.