Five worlds in the Solar System have active volcanoes (those that are currently erupting or have erupted in human history): Earth, Jupiter’s moons Io and Europa, Neptune’s moon Triton, and Saturn’s moon Enceladus. But there are some other worlds that show signs of ancient (and not so ancient) activity. Let’s explore these explosive spots in the solar system.
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Where the lava flows
A volcano is a hole in a planet or moon where hotter material from the inside erupts onto the surface or into the air. On Earth, there are hundreds to thousands of active and potentially active volcanoes. On the Big Island of Hawaii is Mauna Loa, the largest active volcano on Earth. It is 5.5 miles (9 km) high, but more than half of it is underwater. Yellowstone National Park in the United States is located over an extremely volcanic area. Three eruptions in the distant past created a crater 30 by 45 miles (48 by 72 km). Beneath the Pacific Ocean lies the Tamu Massif, a volcano so large it would cover the entire state of New Mexico.
Earth may have many volcanoes, but no place in the solar system is like Jupiter’s moon Io. Io is by far the most volcanic place in the solar system. Every day, hundreds of volcanoes on Io are actively erupting with lava shooting more than 100 miles above the surface. Io has a sea of lava called Loki Patera, which is about a million times larger than the average lava lakes on Earth. And over the course of five months, a mountain the size of Arizona grew on Io’s surface. This little moon literally turns inside out.
Cryovolcanoes
There is another, colder type of volcano that ejects liquids and ices made of water, methane, ammonia and chlorine instead of lava. Called cryovolcanoes, these eruptions form mountains of ice.
Jupiter’s moon Europa is covered in ice. But geysers gush material, including water, through cracks in the surface. Scientists believe that the internal heat source causing these currents may have melted the ice deep inside the planet. If true, Europa may have more water than the entire Earth.
Although Triton, Neptune’s largest moon, is billions of miles from the Sun, it has an internal heat source that makes it volcanically active. Volcanoes on Triton spew gases across this otherwise frozen world.
Saturn’s largest moon, Titan, is big enough to hold a thick atmosphere of nitrogen and methane (not much oxygen, unfortunately, so you couldn’t breathe it). Cryovolcanoes on Titan, Saturn’s largest moon, appear to spew gases above the icy surface, contributing to Titan’s ever-present hazy climate.
But the undeniably cool cryovolcano champion in the solar system has to be Enceladus, Saturn’s small moon. Enceladus is a frozen ball about 313 miles in diameter but it is not frozen solid. NASA’s Cassini spacecraft flew past Enceladus several times and noticed geysers of water erupting through cracks in the moon’s south pole and blasting into space. As the moon circles Saturn, the frozen droplets form a ring around the planet.
Extinct volcanoes
Many worlds in our solar system show evidence of ancient volcanoes and lava flows solidified into fascinating rock formations. Sapas Mons, an extinct volcano on Venus, has two peaks. It is 4 km high and surrounded by old lava flows and landslides.
The Tharsis region of Mars has 12 massive volcanoes. The largest are Olympus Mons, Ascraeus Mons, Pavonis Mons and Arsia Mons. They are up to 100 times larger than all the volcanoes on Earth.
Ahuna Mons is a cryovolcano on the dwarf planet Ceres. It grew from eruptions of mud and salt water that froze on the surface. During the New Horizons mission that flew by Pluto in 2015, astronomers saw signs of cryovolcanoes. Ridges and mountains of ice and ammonia piled up in such a regular fashion that they looked like frozen daggers rising above the otherwise flat plain.
Dean Regas is an astronomer for the Cincinnati Observatory and author of the books 1000 Facts About Space, and How to Teach Grown Ups About Pluto. For a daily space fact, follow him on Instagram:@deanregas.
Tour of the Universe Online Class
What: Astronomer Dean Regas takes you on a virtual tour of it all. Take this fast, fun online course for all ages and interests, right from your home.
When: Tuesday, April 11 at 19.00
Where: Zoom webinar.
Tickets: $10/household.
Information: cincinnatiobservatory.org.
First night of light at the Cincinnati Observatory
What: Celebrate the oldest telescope in the United States as it turns 178. Learn about astronomy, tour the buildings, then look through the 178-year-old telescope at the stars (weather permitting).
When: Friday, April 14 at 8-10 p.m
Where: Cincinnati Observatory, 3489 Observatory Place.
Tickets: 15 USD/adult, 10 USD/child.
Information: cincinnatiobservatory.org.
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