1. Elysium Mons
Location: Mars
Height: 14.1km
Elysium Mons was also discovered by the orbiting Mariner 9 but in 1972. It stands in the surrounding lava plains in Mars’ eastern hemisphere and has a diameter at its base of 149 miles.
Elysium Mons resides on the Elysium Planitia and in 2005 a photo taken by the Mars Express spacecraft showed what could be ash-covered water ice. The ice is thought to be the remains of water floods from the Cerberus Fossae fissures about 2 to 10 million years ago.

2. Ascraeus Mons
Location: Mars
Height: 18km
Ascraeus Mons is the second largest of all these Martian mountains listed reaching 9.3 miles from its base. This volcano’s low profile of just 7 degrees and is filled with volcanic vents. This results in a vast lava flow plain covered in a very fine dust.
It is currently believed that Ascraeus Mons has been active through most of Mars’ history with surrounding craters ranging in age from 200 to 800 million years old.

3. Equatorial Ridge, Saturn’s Moon
Location: Saturn’s moon Iapetus
Height: 20 km
Discovered by the Cassini spacecraft on December 31 2004, Iapetus’ Equatorial Ridge resides on Saturn’s third largest moon. This heavily cratered ridge has a history that is still debated upon.
This ridge runs along the center of Iapetus’ hemisphere and contains some peaks that reach upwards of 12 miles high from the base.
Iapetus is named after the Titan Iapetus, suggested by John Herschel that thought all of Saturn’s moons should be named after the Titans.

4. Rheasilvia Mons
Location: Vesta astreroid
Height: 20-25km
Vesta is the second largest asteroid that orbits our Sun and Rheasilvia is its most prominent feature. Its 314 mile diameter makes up 90 percent of the asteroid’s surface.
It is named after Rhea Silvia, a mythological mother of the founders of Rome and is believed to be an impact crater – one of the largest in the solar system.

5. Boösaule Montes
Location: Io, Moon of Jupiter
Height: 17.2km – 17.8km
Boösaule Montes of IO is the largest non-volcanic mountain in our Solar System. It’s located on IO, the fourth largest and inner-most moon of Jupiter.
From base to peak it reaches 10.6 miles and is just one of 150 discovered mountains on IO’s surface. IO also has over 400 active volcanoes. Boösaule Montes is just one of three mountains connected by a raised plane located on the Pele plume deposit.