Olympus Mons

Mars has a very tall mountain called Olympus Mons. It is a type of volcano called a shield volcano. Olympus Mons is very big. It stands about 21 kilometers high. That is more than two and a half times taller than Mount Everest, the highest mountain on Earth. It is the tallest mountain known in our whole Solar System.

Olympus Mons is part of a place called Tharsis Montes. It last erupted, or exploded, around 25 million years ago. People first saw something bright on Mars in the late 1800s. They called it "Olympic Snow." Later, space probes showed it was a huge mountain.

Scientists have named two big craters on Olympus Mons. These craters may be where some meteorites from Mars, called shergottites, come from. Learning about Olympus Mons helps us understand 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 also very wide, 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 very big volcano on Mars. It is made from many layers of lava that flowed from its top over millions of years. It looks like the volcanoes in the Hawaiian Islands, but it is much larger. Because Mars has less gravity than Earth, the lava could flow farther and make taller mountains.

The top of Olympus Mons has several large craters called calderas. These formed when the magma underneath drained away after eruptions. Scientists think the magma chambers for these calderas are deep below the surface. The shape of the volcano is not perfectly round; one side is steeper and more rugged than the other. This is 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. In 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 located between the northwestern edge of the Tharsis region and the eastern edge of Amazonis Planitia. It is 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 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 bumpy area 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.