Volcanic Activity on Venus Could Explain Phosphine

Ever since the announcement last September that astronomers found evidence of phosphine in the clouds of Venus, the planet has been getting a lot of attention. It’s not surprising. Phosphine is a potential biosignature: On Earth, it is produced by microbial life. Might a similar biological process be taking place in the skies of our sister planet? It’s a tantalizing prospect, and is definitely worth examining closely, but it’s too early to be sure. Microbes aren’t the only way to get phosphine. A new paper published on July 12th in the Proceedings of the National Academy of Science suggests that volcanism might instead be to blame for the strange chemistry in the Venusian cloud tops.

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There Might be Volcanoes at the Bottom of Europa’s sub-ice Oceans

In about three years, NASA plans to launch a robotic orbiter that will study Jupiter’s mysterious moon Europa. It’s called the Europa Clipper mission, which will spend four years orbiting Europa to learn more about its ice sheet, interior structure, chemical composition, and plume activity. In the process, NASA hopes to find evidence that will help resolve the ongoing debate as to whether or not Europa harbors life in its interior.

Naturally, scientists are especially curious about what the Clipper mission might find, especially in Europa’s interior. According to new research and modeling supported by NASA, it’s possible that volcanic activity occurred on the seafloor in the recent past – which could be happening still. This research is the most detailed and thorough 3D modeling on how internal heat is produced and transferred and what effect this will have on a moon.

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The Most Recent Volcanic Activity on the Moon? Just 100 Million Years ago

Regions of the Moon known as irregular mare patches – formed by magma cooling from a volcanic eruption – have almost no big craters, indicating that they must be relatively young. By studying the distribution of craters within them, we can estimate when these regions were formed: no more than 100 million years ago.

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A Crater on Venus Indicates the Planet Hasn’t Been Volcanic for a Long Time

Venus may not have had Earth-like tectonic plates or volcanism for the last billion years, according to a new study. A deep look at a giant impact crater on Venus suggests the planet hasn’t experienced any tectonic activity in the recent past, and might be covered with a in a single outer plate. If so, this would essentially rule out any recent volcanic activity on the planet that many consider Earth’s twin.  

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Lava Tubes on the Moon and Mars are Really, Really Big. Big Enough to Fit an Entire Planetary Base

Could lava tubes on the Moon and Mars play a role in establishing a human presence on those worlds? Possibly, according to a team of researchers. Their new study shows that lunar and Martian lava tubes might be enormous, and easily large enough to accommodate a base.

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The Surprising Possibility That There are Still Active Volcanoes on Venus

Despite the similarities our world has with Venus, there is still much don’t know about Earth’s “Sister planet” and how it came to be. Thanks to its super-dense and hazy atmosphere, there are still unresolved questions about the planet’s geological history. For example, despite the fact that Venus’ surface is dominated by volcanic features, scientists have remained uncertain whether or not the planet is still volcanically active today.

While the planet is known to have been volcanically active as recent as 2.5 million years ago, no concrete evidence has been found that there are still volcanic eruptions on Venus’ surface. However, new research led by the USRA’s Lunar and Planetary Institute (LPI) has shown that Venus may still have active volcanoes, making it the only other planet in the Solar System (other than Earth) that is still volcanically active today.

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What is the Difference Between Active and Dormant Volcanoes?

Volcanoes are an impressive force of nature. Physically, they dominate the landscape, and have an active role in shaping our planet’s geography. When they are actively erupting, they are an extremely dangerous and destructive force. But when they are passive, the soil they enrich can become very fertile, leading to settlements and cities being built nearby.

Such is the nature of volcanoes, and is the reason why we distinguish between those that are “active” and those that are “dormant”. But what exactly is the differences between the two, and how do geologists tell? This is actually a complicated question, because there’s no way to know for sure if a volcano is all done erupting, or if it’s going to become active again.

Put simply, the most popular way for classifying volcanoes comes down to the frequency of their eruption. Those that erupt regularly are called active, while those that have erupted in historical times but are now quiet are called dormant (or inactive). But in the end, knowing the difference all comes down to timing!

Sarychev volcano, (located in Russia's Kuril Islands, northeast of Japan) in an early stage of eruption on June 12, 2009. Credit: NASA
Sarychev volcano, (located in Russia’s Kuril Islands, northeast of Japan) in an early stage of eruption on June 12, 2009. Credit: NASA

Active Volcano:

Currently, there is no consensus among volcanologists about what constitutes “active”. Volcanoes – like all geological features – can have very long lifespans, varying between months to even millions of years. In the past few thousand years, many of Earth’s volcanoes have erupted many times over, but currently show no signs of impending eruption.

As such, the term “active” can mean only active in terms of human lifespans, which are entirely different from the lifespans of volcanoes. Hence why scientists often consider a volcano to be active only if it is showing signs of unrest (i.e. unusual earthquake activity or significant new gas emissions) that mean it is about to erupt.

The Smithsonian Global Volcanism Program defines a volcano as active only if it has erupted in the last 10,000 years. Another means for determining if a volcano is active comes from the International Association of Volcanology, who use historical time as a reference (i.e. recorded history).

Aleutian island #volcano letting off a little steam after the new year on Jan 2, 2016. #YearInSpace. Credit: NASA/Scott Kelly/@StationCDRKelly
Aleutian island #volcano letting off a little steam after the new year on Jan 2, 2016. #YearInSpace. Credit: NASA/Scott Kelly/@StationCDRKelly

By this definition, those volcanoes that have erupted in the course of human history (which includes more than 500 volcanoes) are defined as active. However, this too is problematic, since this varies from region to region – with some areas cataloging volcanoes for thousands of years, while others only have records for the past few centuries.

As such, an “active volcano” can be best described as one that’s currently in a state of regular eruptions. Maybe it’s going off right now, or had an event in the last few decades, or geologists expect it to erupt again very soon. In short, if its spewing fire or likely to again in the near future, then it’s active!

Dormant Volcano:

Meanwhile, a dormant volcano is used to refer to those that are capable of erupting, and will probably erupt again in the future, but hasn’t had an eruption for a very long time. Here too, definitions become complicated since it is difficult to distinguish between a volcano that is simply not active at present, and one that will remain inactive.

Volcanoes are often considered to be extinct if there are no written records of its activity. Nevertheless, volcanoes may remain dormant for a long period of time. For instance, the volcanoes of Yellowstone, Toba, and Vesuvius were all thought to be extinct before their historic and devastating eruptions.

The area around the Vesuvius volcano is now densely populated. Credit: Wikipedia Commons/Jeffmatt
The area around Mount Vesuvius, which erupted in 79 CE, is now densely populated. Credit: Wikipedia Commons/Jeffmatt

The same is true of the Fourpeaked Mountain eruption in Alaska in 2006. Prior to this, the volcano was thought to be extinct since it had not erupted for over 10,000 years. Compare that to Mount Grímsvötn in south-east Iceland, which erupted three times in the past 12 years (in 2011, 2008 and 2004, respectively).

And so a dormant volcano is actually part of the active volcano classification, it’s just that it’s not currently erupting.

Extinct Volcano:

Geologists also employ the category of extinct volcano to refer to volcanoes that have become cut off from their magma supply. There are many examples of extinct volcanoes around the world, many of which are found in the Hawaiian-Emperor Seamount Chain in the Pacific Ocean, or stand individually in some areas.

For example, the Shiprock volcano, which stands in Navajo Nation territory in New Mexico, is an example of a solitary extinct volcano. Edinburgh Castle, located just outside the capitol of Edinburgh, Scotland, is famously located atop an extinct volcano.

An aerial image of the Shiprock extinct volcano. Credit: Wikipedia Commons
Aerial photograph of the Shiprock extinct volcano. Credit: Wikipedia Commons

But of course, determining if a volcano is truly extinct is often difficult, since some volcanoes can have eruptive lifespans that measure into the millions of years. As such, some volcanologists refer to extinct volcanoes as inactive, and some volcanoes once thought to be extinct are now referred to as dormant.

In short, knowing if a volcano is active, dormant, or extinct is complicated and all comes down to timing. And when it comes to geological features, timing is quite difficult for us mere mortals. Individuals and generations have limited life spans, nations rise and fall, and even entire civilization sometimes bite the dust.

But volcanic formations? They can endure for millions of years! Knowing if there still life in them requires hard work, good record-keeping, and (above all) immense patience.

We have written many articles about volcanoes for Universe Today. Here’s Ten Interesting Facts About Volcanoes, What are the Different Types of Volcanoes?, How Do Volcanoes Erupt?, What is a Volcano Conduit?, and What are the Benefits of Volcanoes?

Want more resources on the Earth? Here’s a link to NASA’s Human Spaceflight page, and here’s NASA’s Visible Earth.

We have also recorded an episode of Astronomy Cast about Earth, as part of our tour through the Solar System – Episode 51: Earth.

Sources:

What is the Earth’s Mantle Made Of?

The Earth's layers, showing the Inner and Outer Core, the Mantle, and Crust. Credit: discovermagazine.com

Like all the other terrestrial planets, (Mercury, Venus, and Mars) the Earth is made up of many layers. This is the result of it undergoing planetary differentiation, where denser materials sink to the center to form the core while lighter materials form around the outside. Whereas the core is composed primarily of iron and nickel, Earth’s upper layer are composed of silicate rock and minerals.

This region is known as the mantle, and accounts for the vast majority of the Earth’s volume. Movement, or convection, in this layer is also responsible for all of Earth’s volcanic and seismic activity. Information about structure and composition of the mantle is either the result of geophysical investigation or from direct analysis of rocks derived from the mantle, or exposed mantle on the ocean floor.

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Warm, Flowing Water on Mars Was Episodic, Study Suggests

Though the surface of Mars is a dry, dessicated and bitterly cold place today, it is strongly believed that the planet once had rivers, streams, lakes, and flowing water on its surface. Thanks to a combination of spacecraft imagery, remote sensing techniques and surface investigations from landers and rovers, ample evidence has been assembled to support this theory.

However, it is hard to reconcile this view with the latest climate models of Mars which suggest that it should have been a perennially cold and icy place. But according to a new study, the presence of warm, flowing water may have been an episodic occurrence, something that happened for decades or centuries when the planet was warmed sufficiently by volcanic eruptions and greenhouse gases.

The study, which was conducted by scientists from Brown University and Israel’s Weizmann Institute of Science, suggests that warmth and water flow on ancient Mars were probably episodic, related to brief periods of volcanic activity that spewed tons of greenhouse-inducing sulfur dioxide gas into the atmosphere.

The work combines the effect of volcanism with the latest climate models of early Mars and suggests that periods of temperatures warm enough for water to flow likely lasted for only tens or hundreds of years at a time.

The notion that Mars had surface water predates the space age by centuries. Long before Percival Lowell observed what he thought were “canals” on the Martian surface in 1877, the polar ice caps and dark spots on the surface were being observed by astronomers who thought that they were indications of liquid water.

Curiosity found evidence of an ancient, flowing stream on Mars at a few sites, including the "Hottah" rock outcrop pictured here. Credit: NASA/JPL
Curiosity found evidence of an ancient, flowing stream on Mars at a few sites, including the “Hottah” rock outcrop pictured here. Credit: NASA/JPL

But with all that’s been learned about Mars in recent years, the mystery of the planet’s ancient water has only deepened. The latest generation of climate models for early Mars suggests that the atmosphere was too thin to heat the planet enough for water to flow. Billions of years ago, the sun was also much dimmer than it is today, which further complicates this picture of a warmer early Mars.

“These new climate models that predict a cold and ice-covered world have been difficult to reconcile with the abundant evidence that water flowed across the surface to form streams and lakes,” said James W. Head, professor of earth, environmental and planetary sciences at Brown University and co-author of the new paper with Weizmann’s Itay Halevy. “This new analysis provides a mechanism for episodic periods of heating and melting of snow and ice that could have each lasted decades to centuries.”

Halevy and Head explored the idea that heating may have been linked to periodic volcanism. Many of the geological features that suggest water was flowing on the Martian surface have been dated to 3.7 billion years ago, a time when massive volcanoes are thought to have been active.

And whereas on Earth, widespread volcanism has often led to global dimming rather than warming – on account of sulfuric acid particles reflecting the sun’s rays – Head and Halevy think the effects may have been different in Mars’ dusty atmosphere.

To test this theory, they created a model of how sulfuric acid might react with the widespread dust in the Martian atmosphere. The work suggests that those sulfuric acid particles would have glommed onto dust particles and reduced their ability to reflect the sun’s rays. Meanwhile, sulfur dioxide gas would have produced enough greenhouse effect to warm the Martian equatorial region so that water could flow.

Image of the McMurdo Dry Valleys, Antarctica,  acquired by Landsat 7’s Enhanced Thematic Mapper plus (ETM+) instrument. Credit: NASA/EO
Image of the McMurdo Dry Valleys, Antarctica, acquired by Landsat 7’s Enhanced Thematic Mapper plus (ETM+) instrument. Credit: NASA/EO

Head has been doing fieldwork for years in Antarctica and thinks the climate on early Mars may have been very similar to what he has observed in the cold, desert-like.

“The average yearly temperature in the Antarctic Dry Valleys is way below freezing, but peak summer daytime temperatures can exceed the melting point of water, forming transient streams, which then refreeze,” Head said. “In a similar manner, we find that volcanism can bring the temperature on early Mars above the melting point for decades to centuries, causing episodic periods of stream and lake formation.”

As that early active volcanism on Mars ceased, so did the possibility of warmer temperatures and flowing water.

According to Head, this theory might also help in the ongoing search for signs that Mars once hosted life. If it ever did exist, this new research may offer clues as to where the fossilized remnants ended up.

“Life in Antarctica, in the form of algal mats, is very resistant to extremely cold and dry conditions and simply waits for the episodic infusion of water to ‘bloom’ and develop,” he said. “Thus, the ancient and currently dry and barren river and lake floors on Mars may harbor the remnants of similar primitive life, if it ever occurred on Mars.”

The research was published in Nature Geoscience.

Further Reading: Brown University

Mercury Had Quite The Explosive Past, Spacecraft Analysis Shows

Mercury — a planet once thought to have no volcanism at all — likely had a very active past, a new analysis of images from NASA’s MESSENGER spacecraft shows. After looking at 51 vents across Mercury, the team concluded that they show different amounts of erosion — hinting that the explosions happened at different times in the planet’s history.

“If [the explosions] happened over a brief period and then stopped, you’d expect all the vents to be degraded by approximately the same amount,” stated Goudge, a graduate geology student at Brown University who led the research.

“We don’t see that; we see different degradation states. So the eruptions appear to have been taking place over an appreciable period of Mercury’s history.”

Information came from orbital data collected from MESSENGER (MErcury Surface, Space ENvironment, GEochemistry and Ranging) since 2011, which provided more consistent data than the previous flybys, the researchers added. To better figure out the age of these vents, they examined those that are located in impact craters; any vents there before the impact occurred would have been wiped out.

Two pyroclastic vents in Mercury's Kipler crater in optical (top) and false-color views from NASA's MESSENGER spacecraft. Pyroclastic material is in brown-red in the bottom image. The vents were likely too fragile to survive the impact of the crater, scientists said, showing that they likely arose after the impact occurred. Credit: Brown University/NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
Two pyroclastic vents in Mercury’s Kipler crater in optical (top) and false-color views from NASA’s MESSENGER spacecraft. Pyroclastic material is in brown-red in the bottom image. The vents were likely too fragile to survive the impact of the crater, scientists said, showing that they likely arose after the impact occurred. Credit: Brown University/NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

The vents show up along with deposits of pyroclastic ash, which are leftovers of volcanic explosions. This shows that like Earth, the interior of Mercury has volatiles or compounds that have low boiling points. (Earth examples of these are water and carbon dioxide.)

By looking at the pattern of erosion in the craters, Goudge found that there are pyroclastic deposits in craters that are between 1 and 3.5 billion years old. By comparison, Mercury and the rest of the solar system formed about 4.5 billion years ago, and the finding shows the pyroclastic activity happened well after then.

“These ages tell us that Mercury didn’t degas all of its volatiles very early,” Goudge added. “It kept some of its volatiles around to more recent geological times.”

You can read more about the study in the Journal of Geophysical Research.

Source: Brown University