Space mountains

SPACE

“ The largest shield volcano on Earth – Mauna Loa in Hawaii – is smaller than the largest caldera on Olympus Mons”

When placed next to two of the Earth’s tallest mountains, you can see just how big Mars’s Olympus Mons really is

Mount Everest

Mount Everest is the highest peak on Earth above sea level at 8,848m (29,029ft), though mountains in the rest of the Solar System are measured from their bases.

Olympus Mons

At about 22km (13.7mi) tall, Olympus Mons is two and a half times taller than Mount Everest, and over double Mauna Kea’s height too.

Giant space mountains

Everest has nothing on mighty peaks elsewhere in the Solar System…

We marvel at Mount Everest, the highest peak on Earth at 8,848 metres (29,029 feet). Yet in comparison to some of the other mountains found in our Solar System, it’s positively puny. Since its discovery in 1971, Olympus Mons has held the title of tallest mountain in the Solar System. It is a shield volcano located in the western hemisphere of Mars, and has a height of about 22 kilometres (13.7 miles) when measured from base to summit. Olympus Mons looks a lot like the volcanoes that make up Hawaii. It’s asymmetrical, has a low profi le and is probably built up from thousands of basaltic lava fl ows.

In 2011, a mountain on 4 Vesta – an asteroid designated as a minor planet – was named as a potential challenger to Olympus Mons. Since Vesta is one of the largest asteroids in the Solar System, it makes sense that it would have one of the tallest mountains. Thought to be an impact crater, Rheasilvia is the most prominent feature on the rocky body. The central peak in Rheasilvia has also been measured at 22 kilometres (13.7 miles) from its base. First spotted by the Hubble Space Telescope in 1997, the crater was more closely examined by NASA’s Dawn space probe. Given the margin of error for measuring space mountains, Olympus Mons still offi cially holds the designation of tallest mountain in the Solar System.

The third-highest mountain is one of the most unusual. Found on Iapetus, Saturn’s third-largest natural satellite, it doesn’t even have a name of its own beyond ‘equatorial ridge of Iapetus’. But it is an incredibly dramatic feature, dividing the moon at its equator and giving it a walnut-like appearance. The ridge contains numerous isolated peaks along its 1,500 kilometres (930 miles), some of them estimated at more than 20,000 metres (65,617 feet). We don’t yet know how the ridge formed or why it’s located along the moon’s equator.

Calderas on Olympus Mons

Olympus Mons has a complex of calderas and caldera segments at its peak – cauldron-like depressions that form when a volcano’s roof collapses after an eruption. Each one indicates a separate eruption in the history of the volcano. Olympus Mons’ largest caldera is 80 kilometres (50 miles) wide and was probably a lava lake. By comparison, the largest shield volcano on Earth – Mauna Loa in Hawaii – is smaller than the largest caldera on Olympus Mons!

DID YOU KNOW?

Olympus Mons is so big and shallow that if you stood on Mars you could never see its entire profile

Base area

At nearly 700km (435mi) across Olympus Mons’ width is just as impressive as its height. This diagram shows how it would sit if it were placed in France.

Mauna Kea

If measured from its base, Hawaii’s Mauna Kea is over 10,000m (32,800ft) – taller than Mount Everest.

FRANCE

The real Mount Doom?

Titan, Saturn’s largest moon, is home to a mountain range named Doom Mons. This range is in the southern hemisphere of the moon and stands out on the mostly smooth surface. It may be the largest mountain range on Titan, estimated at 1.5 kilometres (0.9 miles) tall. The International Astronomical Union’s naming convention for mountains on Titan is to name them after mountains in JRR Tolkien’s works, although Doom Mons has an unknown origin. It is located near Sotra Patera, a cryovolcano that is over 30 kilometres (20 miles) across.

A topographical map of Titan put together using data from the Cassini probe. Doom Mons is located in the red region on the right; inset, Titan

How do space peaks form?

1Volcanic activity Large volcanic mountains often form from fl uid lava fl ows, and may be larger than terrestrial volcanoes due to a lack of tectonic plates on the particular body.

2Tectonics These mountains form due to the movement of plates in the crust, caused by compressive forces within the planet or moon.

3Impact Large projectiles like asteroids striking a planet or moon can leave more than craters; they can also fault and fracture the surface to create new mountains.