Earth's biggest volcano would be a foothill out there. Nine giants — from ice fountains to a country-sized lava lake — counting down to a 22 km monster.
Our yardstick. Measured from its true base on the seafloor, Mauna Loa rises about 17 km and holds 75,000 cubic km of lava. Everything after this one beats it.
A 4 km dome on a dwarf planet only 940 km wide. It never erupted lava — it oozed briny ice slush, which froze into the bright streaks down its flanks.
Roughly 150 km across and 4.7 km tall, with a vast hollow at its summit. At -230°C, Pluto's magma is a slurry of water ice, ammonia and methane.
Saturn's small icy moon fires water hundreds of kilometres into space through cracks near its south pole. That spray is what builds Saturn's enormous E ring.
Voyager 2 caught plumes shooting 8 km up from Neptune's largest moon — about 140 times the reach of Old Faithful, on a surface colder than -235°C.
A lava lake 200 km wide, rimmed with molten rock and dotted with islands. It has been erupting every single time astronomers have looked since 1979.
Venus's tallest volcano climbs 8 km. In 2023, researchers re-examined Magellan radar from 1990-92 and found a vent that changed shape — a live eruption.
Only about 7 km tall, yet its lava flows reach 1,350 km from the summit. It blankets more of Mars than any other volcano — so broad it barely reads as a mountain.
The champion: about 22 km high and 600 km across, roughly 2.5 times the height of Everest. Stand at its base and the summit would sit beyond the horizon.
Io alone throws lava higher than any volcano Earth has managed. The solar system is a long way from geologically dead.