Across our planet, on every continent, there is a volcano.
Although most are in a dormant state, we still see on average 50-70 eruptions every year.
Some of which, are extremely destructive, destroying people's lives and property.
But the Earth is not the only place in the solar system where these dramatic events unfold,
because other planets and moons have their own volcanic stories to tell.
Evidence of past volcanic activity has been found on all of the rocky inner planets
and many of the solar system's moons. Our moon, for example, has vast areas covered with
ancient lava flows, while Mars boasts Olympus Mons, the largest volcano ever discovered.
However, most of these volcanic features formed millions of years ago and are now just the scars
of once active worlds. But we do know of at least five bodies throughout the solar system,
including Earth, that are still volcanically active.
The word "Volcano" comes from the Roman god of fire,
Vulcanus, and nowhere is that name more suited than IO. With hundreds of active volcanoes,
this rocky moon of Jupiter is considered the most volcanic world in the solar system.
The hellish moon is covered with volcanos spewing fountains of lava and sulphurous gases high above
its bizarre surface. Here, you will not find lakes of water but instead great lakes of molten rock.
The largest, named Loki Patera, is more than 126 miles across, which is more than 202 kilometres
across. It is a million times the area of any lava lake found on Earth. It is a vision of hell.
This photo, captured by Voyager One in 1979, reveals the bizarre volcanic lake from above,
as a giant shield-shaped black feature, with a mysterious island in the middle.
Research has shown that cooling molten rock in the volcanic lake periodically sinks,
allowing a dramatic wave of fresh lava that starts at one end, to flow around the middle island and
converge on the other side. A phenomenon that strangely occurs once every 500 days or so.
In 2007 NASA's New Horizons spacecraft captured an eruption
in action, which can be seen in this sequence of photos.
The incredible time lapse is over an 8 minute period and shows a plume of volcanic debris around
200 miles high, which is around 320 kilometres high, drifting above the moons hellish surface.
IO is being stretched and squeezed in a gravitational tug of war between Jupiter
and the other large Galilean moons. Its rocky surface bulges up and down during the process,
similar to how our moon affects the oceans of Earth. But on IO, tidal forces generate
tremendous amounts of heat in the moon's interior, causing subsurface magma oceans
that are seeking any available escape to relieve the immense pressure from within.
You can imagine it a bit like squeezing a ball of clay in your hand. Eventually,
the clay becomes warm due to friction, and this is similar to what is happening on IO,
just on a much larger and more violent scale.
Closer to home, we find Venus, a planet with more volcanos than any other planet in the solar
system. There is no doubt volcanic activity has played a pivotal role in its history,
but it is unsure whether they are still active.
Venus is a difficult planet to study because of its thick, corrosive, scorching atmosphere.
Meaning that spacecraft can only survive for a matter of minutes on its surface,
unlike Mars, where they can last for years. Recently a study has possibly
identified 37 volcanic structures that may indicate that Venus is still active,
however. Although, scientists are yet to image them directly.
Most of the volcanos on Venus are classed as shield volcanos,
such as the planets largest, Maat Mons. But there are some unusual volcanic features that
have been discovered using radar images captured by the Magellan spacecraft in the early 1990s.
These strange pancake-like domes can be found across the planet and likely formed
when unusually thick lava oozed out of the surface and spread evenly in all directions.
This strange dome-shaped volcano has lava channels radiating from the centre and is about 62 miles
across or 100 kilometres across. More than three times the width of Mount Everest. Several
magnificent ancient flows can be seen that resemble the shape of a fan
and once again were likely formed by very thick, viscous lava.
Other than Earth, IO and possibly Venus, no other world in the solar system is
known to have actively erupting volcanoes spewing out magma. There are, however,
frozen worlds in the outer solar system where flowing ice takes the place of molten rock.
The very idea of a frozen volcano, known as a cryo-volcano,
is so strange that it was never even considered a possibility until the Voyager missions in 1979.
While flying past the moons of the gas giants, the twin spacecraft
sent back bizarre images that resembled smooth lava plains and volcanic like mountains.
Most people define the word "volcano" as an opening in the Earths surface
from which molten rock, gases, and volcanic ash can escape.
A cryo-volcano isn't all that different. It forms from pressure beneath the surface,
but rather than molten rock, it erupts molten ice, sometimes called cryo-magma.
They can erupt violently or flow gently, just like the volcanoes we see on Earth, and in 2005 the
Cassini spacecraft captured plumes of ice being ejected from Saturns bright white moon, Enceladus.
Although not in the form of a towering volcanic mountain,
the South Pole of Enceladus is scattered with more than 100 geysers-like features.
The presence of these powerful jets indicates that liquid water was bubbling
up from a layer under the moons frozen crust, providing evidence of a subsurface ocean.
It is thought that oceans of water a short distance beneath the frigid surface is heated
by tidal interactions with Saturn, similar to the process that makes IO so volcanic.
When the icy material bursts out of the moons frozen crust,
some of it falls back onto the moon, replenishing its bright white surface,
while the rest escapes into space and forms part of Saturn's magnificent ring.
A similar cloud of icy debris has also been seen coming from Jupiters moon
Europa in 2012, indicating that it too may have a subsurface ocean. But orbiting the solar systems
most distant planet, Neptune, the mysterious moon Triton is where Cryo-volcanism was first observed.
As Voyager two flew past Triton in 1989, marking the first and last time the moon was ever visited,
it captured incredible images of its unusual surface.
Triton is a rugged moon covered with rising blobs of ice,
faults and frozen lava flows composed of water and other ices. However, its surface
is also extremely young and sparsely cratered, indicating that it is still geologically active.
The dark streaks seen across Tritons south polar region are thought to be dust deposits
left by recent eruptions of nitrogen ice. Scientists believe the eruptions are created by
dark particles inside Tritons ice caps absorbing the distant sunlight, which slowly warms nitrogen
ice and causes pressured gas pockets to jet out and drift across its frozen surface.
Volcanism outside of Earth mainly occurred in the early stages of
the solar system when the planets were much hotter. Now, only Earth and IO are
confirmed to have molten rock spewing from violent chasms in their surfaces.
Venus may well be added to that list in time, but further research is required.
Many of the icy worlds in the outer solar system have in recent times
revealed themselves to also be active, erupting molten ice instead of molten rock.
Even Pluto has a possible active cryo-volcano, seen by New Horizons in 2015.
These distant frozen worlds may seem like frigid wastelands at first glance, but if
we take a closer look, there seems to be a mystery hidden beneath the surface waiting to burst free.