Explore Outer Space with “NOVA: Solar System”

Take a journey across the galaxy and explore fascinating wonders that typically go unnoticed on planets across our solar system. From wandering spatial bodies, to otherworldly volcanoes, this season of “NOVA” is filled with the lesser-known marvels of the solar system. Watch the special mini-series, “NOVA: Solar System,” every Wednesday this month at 8 p.m. or stream afterwards on PBS.org.

“Volcano Worlds,” the third episode of the mini-series, reveals the impact volcanic eruptions have had on planets across the galaxy and how they contribute to planetary atmospheres. In anticipation of the episode, we spoke to Texas A&M geology professor Dr. David Sparks to give us a little more insight into the world of volcanoes.

What is a volcano and how are they formed?

Volcanoes aren’t always the mountains that probably come to mind.

“A volcano is a place where molten rock, or magma, and other gases are released on the surface of a planet,” Dr. Sparks said. “If eruptions are large enough and happen in the same place for a long enough period of time, the solidified material can build up a mountain, which is what most people think of as a volcano.”

On Earth, there are two ways volcanoes can form. When molten rock deep in the earth rises to the crust, it eventually reaches the surface, creating a hotspot. Volcanoes can also form in areas where oceanic plates have sunk beneath one another or beneath a continental plate. This process creates a typical volcanic mountain that builds up.

The amount of time it takes to form a volcano depends on the amount and frequency of its eruptions. Although a single eruption can add several tens of meters of lava and ash to a mountain, it may only happen every 1,000 years.

“It’s thought that Mt. Fuji in Japan began to form about 100,000 years ago to create the mountain we see today, though it hasn’t erupted for hundreds of years,” Dr. Sparks said.

Why do volcanoes erupt?

Dr. Sparks says there are several reasons and each eruption can depend on a variety of factors.

“Sometimes, large eruptions happen because earthquakes can trigger large landslides that open up a path for the magma,” Dr. Sparks said. “If there are dissolved volatiles, such as water, carbon dioxide or sulfur dioxide in the magma, once the magma begins to rise rapidly into cracks, these volatiles come out as bubbles, which accelerate the rise and cause the explosion.”

What about volcanoes in outer space?

You might not think about volcanoes on other planets, but Dr. Sparks says they absolutely exist.

“Volcanic activity occurs – or occurred in the distant past – on other planets for much the same reason as on Earth,” Dr. Sparks said.

And these volcanoes aren’t just limited to hot planets.

“There are many small solid bodies in the very cold outer part of the solar system, like Pluto, that had or still have some volcanic activity,” Dr. Sparks said, “although the surface ‘rock’ is actually ice, and the ‘magma’ is liquid water, methane or nitrogen.”

How do eruptions shape planets?

When a volcano erupts, it covers existing land with lava and ash, creating new rock. However, volcanic activity on Earth mainly occurs in the Ring of Fire and near the boundaries of tectonic plates, so these eruptions are not significant to shaping our world.

As for other planets, Dr. Sparks says “no other place in our solar system has surface water, and few have any atmosphere. In those places volcanic features are preserved for a long time and are the dominant features.”

Dr. Sparks gave us a couple of examples – one of which is pretty familiar to us.

“The Moon is geologically dead now and is covered in volcanic rock formed at least 3.5 billion years ago,” Dr. Sparks said. “[Jupiter’s satellite] Io has great internal heating, because it orbits through Jupiter’s massive gravitational field, so its surface is completely repaved with new lava every one to two million years.”

Wondering what other cosmic phenomenons you’ve been missing out on? Learn more by watching “NOVA: Solar System” every Wednesday this month at 8 p.m. or stream afterwards on PBS.org and don’t miss this week’s episode, “Volcano Worlds,” airing Oct. 16 at 8 p.m.!

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