Archive for April, 2012

Happy birthday, Athanasius Kircher

April 30th, 2012 by Michon Scott

By the year 1631, residents of southern Italy had perhaps grown complacent about the volcano that destroyed Pompeii. But near the end of that year, Mount Vesuvius reminded them of its power. From December 1631 to January 1632, explosive activity at Vesuvius caused a caldera collapse, a tsunami, mud flows, scorched farms, and up to 4,000 deaths. It was the volcano’s most destructive eruption since 79 AD.

The volcano was still rumbling several years later when it received a distinguished visitor: Athanasius Kircher, a German Jesuit mathematician and linguist living in Rome. Unlike his sensible contemporaries, he didn’t admire the volcano from a respectable distance. He descended into the active crater.

I reached Portici, the town at the roots of the mountain, and from there was led by a trusty peasant who knew the way, paying him a handsome fee. In the middle of the night I climbed the mountain by hard and rugged paths. When I reached the crater, horrible to relate, I saw it all lit up by fire, with an intolerable exhalation of sulfur and burning bitumen. Thunderstruck by the unheard-of spectacle, I believed I was peering into the realm of the dead, and seeing the horrid phantasms of demons, no less, perceived the groaning and shaking of the dreadful mountain, the inexplicable stench, the dark smoke mixed with globes of fire which the bottom and sides of the mountain continuously vomited forth from eleven different places, forcing me at times to vomit out myself . . . When dawn broke, I decided to explore diligently the whole of the interior constitution of the mountain. I chose a safe place where a firm foothold might be had, and descended to a vast rock with a flat surface to which the mountain slope gave access. There I set up my Pantometer and measured the dimensions of the mountain.

It was a bigger risk than most people would take, but by the time Kircher descended into the rumbling crater of Vesuvius, he had survived a shipwreck, gangrene, trampling by horses, a trip through the grinding wheel of a mill, and a near execution by Protestant soldiers in the Thirty Years War. So maybe a mere volcano didn’t intimidate him.

Kircher's engraving of Vesuvius in Mundus Subterraneus. Now appears in Athanasius Kircher's Theater of the World by Joscelyn Godwin.

He visited and studied Vesuvius, Etna, and Stromboli, and between 1664 and 1678 he published his observations in Mundus Subterraneus (The Subterranean World). In his twelve volumes, Kircher suggested that volcanoes owed their heat to the combustion of sulfur, bitumen, and niter (a chemical composition similar to gunpowder). His assumption was understandable considering volcanic eruptions release gases, including the sulfur that nauseated him at Vesuvius. He also realized that the amount of molten material released by a volcano often exceeded what the volcano itself could contain. He surmised that volcanoes were vents for material deep within the planet’s interior. Furthermore, he realized that volcanic activity could destroy some mountains while building others.

Kircher produced a diagram of the Earth’s interior to illustrate his hypothesis. Although quite different from geologists’ current understanding of our planet’s core, his hypothesis of a central source of heat inside the planet, and his realization that volcanoes and earthquakes are a global phenomenon, are now widely accepted.

Kircher's diagram of the Earth. Image courtesy Linda Hall Library of Science, Engineering and Technology

Kircher’s Mundus Subterraneus also discussed fossils. In Kircher’s day, naturalists had not yet figured out how fossils formed, and explanations varied from a creative force in the planet to the handiwork of angels. Kircher didn’t have a modern paleontologist’s understanding, but he did interpret some fossils correctly. And while some of his contemporaries attributed big skulls and femurs to giants, he wondered where the giants could find enough room to live and meat to eat. (The bones are now recognized as the remains of mammoths and mastodons.)

Kircher was a polymath who published on many topics besides Earth science, and his Mundus Subterraneus was a curious mixture of good science and weird old lore, including topics such as mining, gravity, magnetism, the Sun, the Moon, weather, bioluminescence, fireworks, herbal remedies, poisons, antidotes, astrology, demons, dragons, and subterranean men. Chased out of his native Germany by the violence of the Thirty Years War, he settled briefly in France before being summoned to Rome to teach mathematics and interpret Egyptian hieroglyphs. In fact, Kircher was summoned to Rome in the wake of the condemnation of Galileo Galilei. Church authorities wanted a showman who could rival’s Galileo’s talent and wit.

Kircher wasn’t ahead of his time in every respect. A believer in spontaneous generation of life forms, Kircher published recipes. Perhaps more remarkably, he believed in dragons, at least when they were vouched for by an authority (particularly a pope). In fact, in the words of one science historian, “Kircher was perhaps the last naturalist to believe passionately in the reality of any papal dragon he saw.” Dragons were featured in Mundus Subterraneus alongside astute observations about volcanoes and fossils.

One of Kircher's dragon engravings. Now appears in Athanasius Kircher's Theater of the World by Joscelyn Godwin.

How could the same person who made correct observations about Earth sciences still believe in dragons? For starters, it was politically shrewd to believe in the things your patrons believed in, including the occasional mythological creature. And it’s important to remember the age in which Kircher lived. Even in the seventeenth century, belief in supernatural beings was fairly common, and the religious and political uncertainty of the times fueled outlandish rumors of monsters, bad omens, and witches. When the mother of the great astronomer Johannes Kepler was put on trial for witchcraft, Kepler rushed to her defense and assured the authorities she wasn’t a witch. But he didn’t argue that there was no such thing as a witch.

History hasn’t remembered Kircher as generously as Galileo or Kepler, but the Jesuit is worth remembering. Kircher was born on May 2, the feast day of St. Athanasius. While he remembered the date of his birth, he wasn’t so sure about the year: 1601 or 1602. So May 2, 2012, marks Kircher’s 410th or 411th birthday.

Further reading

Findlen, P. ed. (2004) Athanasius Kircher: The Last Man Who Knew Everything. New York: Routledge.

Godwin, J. (2009) Athanasius Kircher’s Theatre of the World. Rochester: Inner Traditions.

Harrington, R. (2009, June 13) Athanasius Kircher’s “Mundus Subterraneus” (1664). The Volcanism Blog. Accessed April 21, 2012.

Principe, L.M. (2011). The Scientific Revolution: A Very Short Introduction. New York: Oxford University Press.

Rowland, I.D. (2000) The Ecstatic Journey: Athanasius Kircher in Baroque Rome. Chicago: University of Chicago Library.

Rudwick, M.J.S. (1976) The Meaning of Fossils: Episodes in the History of Paleontology. Chicago: University of Chicago Press

Smith, P.H., Findlen, P. eds. (2002) Merchants and Marvels. New York: Routledge.

Yamada, T. (2006)  Kircher and Steno on the “geocosm,” with a reassessment of the role of Gassendi’s works. Geological Society of America Special Papers.

Quickening Water Cycle, Risat-1 Launches, and More

April 27th, 2012 by Adam Voiland


Study: Quickening Water Cycle Fueling Extreme Weather
There’s been no shortage of extreme weather in recent years, from flooding in Australia to record-breaking temperatures in North America to wildfires in Russia. A new study published in Science argues that at least some of the blame should go to global warming for accelerating the water cycle. By measuring changes in the salinity of the ocean’s surface, the authors conclude that the water cycle has sped up by 4 percent over the last half century. The research is based on data from ships and a network of floating Argo sensors, not satellite data. However, NASA’s newly-launched Aquarius satellite will likely provide better global salinity estimates in the coming years. In other extreme weather news, a new poll found that two-thirds of Americans believe global warming is exacerbating severe weather and a new video (above) from the Yale Forum on Climate Change tackles the subject as well.

Welcome to the Earth-observing Club, Risat-1
On April 26, India’s space agency successfully launched Risat-1, an Earth-observing satellite carrying a synthetic aperture radar system. Though it’s been called a spy satellite, Risat-1 will more likely be used to monitor the health of forests and agriculture and to predict natural disasters, according to Space Daily. Risat’s radar is capable of collecting images in all weather conditions and can “see” through tropical clouds and rain showers; it can also image the Earth at night. India currently has 11 Earth-observing satellites in orbit. The Canadian RADARSAT SAR, Europe’s Envisat (which recently went AWOL), and the Space Shuttle have flown similar instruments in the past.

Helmets for Severe Weather Week?

Around this time last year, fierce storms barreled through the central and southern United States, spawning more than 300 tornadoes that took hundreds of lives. This year, tornadoes have already killed 63 people (more than 100 tornadoes ripped through several Plains states just a few weeks ago), but tornado season hasn’t even hit its peak yet. Due to a lack of data, it’s up for debate whether climate change is fueling such outbreaks. Regardless of the cause, NOAA and FEMA are sponsoring the first ever severe weather preparedness week in an effort to limit the death toll of future storms. Meanwhile, NPR ran an interesting story that questions why the Centers for Disease Control and Prevention recommends people use their hands rather than helmets to protect their heads during twisters.

Study Suggests Chinese Dam and Earthquake are Linked
A disastrous 7.9 earthquake struck Wenchuan, China, in 2008, killing 80,000 thousand people. Ever since, many scientists have wondered whether the quake may have been triggered by the construction of nearby Zipingpu Dam, which put 900 million tons of water on top of the fault that was at the epicenter of the quake.  Some scientists believe the pressure from the reservoir could have pushed water into the fault, lubricating and weakening it enough to cause it to slip. Though the topic remains controversial, a new article in Science reviews new evidence that suggests the dam and earthquake were linked.

Nepal Gets a New Tool for Monitoring Wildfires
In the last few days, hundreds of fires have burned across the southern belt of the  Hindu-Kush Himalayan region. The MODIS instrument on NASA’s Aqua satellite captured this view of the burning on April 24. Should you be interested in monitoring Nepalese wildfires, the International Center Integrated Mountain Development just released a pilot version of a new monitoring system based on MODIS data. Go here to check it out.

Next Stop: The Arctic Circle
Operation IceBridge, NASA’s multi-year mission that maps polar ice, has passed the mid-point of its current mission to the Arctic.  You can visit this page for more details and follow along on the IceBridge blog.

Note: Click on the images for larger views and crediting information.

This Week’s Earth Indicator: 76

April 11th, 2012 by Adam Voiland


This map, based on data from the Moderate Resolution Imaging Spectroradiometer (MODIS), shows average aerosol amounts around the world for March 2012. An optical thickness of less than 0.1 ( palest yellow) indicates crystal clear sky with maximum visibility, whereas a value of 1 (reddish brown) indicates very hazy conditions.


This week’s indicator: 76. No, that is not a reference to the return time of Halley’s Comet (76 years) or the atomic number of the world’s densest natural element (the metal osmium). In this case, 76 is a percentage.  And it’s a particular percentage that represents how much of the variability in North Atlantic sea temperatures new climate simulations attribute to small airborne particles called aerosols. British scientists at the Met Office Hadley Center ran the simulations, and Nature published the numberin a recent issue.

North Atlantic sea temperatures have gone through warm and cool phases over the last 150 years (a phenomenon called the Atlantic Multidecadal Oscillation, or AMO). The sea was cool, for example, during the 1900s–1920s and 1960s–1990s, while a warm phase occurred in the 1930s–1950s (see graph below). Since the mid-1990s, the North Atlantic has been in a warm phase.

The difference between average ocean surface temperatures over the North Atlantic and those over the global oceans has oscillated between cool and warm phases. Figure from the April 4, 2012 edition of Nature.

That may sound like arcane trivia, but the cycling of North Atlantic sea temperatures matter. Earlier research has linked its phase (warm or cool) to high-stakes weather events, such as the frequency of Atlantic hurricanes and drought in the the Amazon Basin and the Sahel. Cool phases, for example, have coincided with decreased rainfall in the Amazon, more Atlantic hurricanes, and increased rain in the Sahel.

Conventional wisdom has held that the cycling of North Atlantic sea temperature is a natural phenomenon driven by ocean currents. The new climate simulations suggest that aerosols are the real culprit. The British team considered a number of aerosol types in their analysis but the most important was one called sulfates, which come from volcanic eruptions and from humans burning fossil fuels.

The researchers used a state-of-the-art climate model to see if they could reproduce the changes in North Atlantic sea temperatures seen over the last 150 years. This wasn’t the first time scientists have tried this, but it was the first time any group did it so accurately. And the key to their success, the British team concluded, was that they incorporated better estimates of how aerosols affect clouds—something that most previous models omitted or only partially included.

How do aerosols (for the sake of simplicity, let’s just call it pollution for the moment) affect clouds and how does that affect sea surface temperature?  In short, pollution tends to brighten clouds (see illustration above) causing the clouds to reflect more light back to space and cool the sea.

Clouds in clean air are composed of a relatively small number of large droplets (left). As a consequence, the clouds are somewhat dark and translucent. In air with high concentrations of aerosols, water can easily condense on the particles, creating a large number of small droplets (right). These clouds are dense, very reflective, and bright white. This influence of aerosols on clouds is called the “indirect effect.” NASA image by Rob Simmon.

After taking this indirect aerosol effect into account, the British team’s simulations suggested that the majority (the number they came up with was, of course, 76 percent) of the observed variability in sea temperatures seen since 1860 was due to cooling caused by sulfates from volcanic eruptions and from the buildup of industrial pollution. The results of the simulation also imply that sea  temperatures have risen in recent decades because clean air regulations passed in the United States and Europe in the 1960s and 1970s have reduced levels of air pollution.

If the new simulation is right, it would be a big deal. It would not only mean, as a Nature News & Views article pointed out, that humans are the key factor driving changes in sea surface temperatures (and that cleaning up the air could be fueling hurricanes); it would also mean that the Atlantic Multidecadal Oscillation (AMO) doesn’t really exist.

Before you start mourning its death, however, realize there are some indications that this latest simulation may not be right. Understanding how aerosols affect clouds remains a young science, and the British team may have made some incorrect assumptions about how aerosols affect particular types of clouds. Plus, the model didn’t reproduce changes in the frequency of outbreaks of African dust storms, something that can affect the temperature of the tropical Atlantic. On top of all that, a number of other studies have come to very different conclusions.

Bottom line: stay tuned. Things can get messy at the cutting-edge of science, but we’ll be keeping our eye out to see if and how long the 76 percent number holds.

Science is full of numbers and here at the Earth Observatory we know they can sometimes be contradictory and confusing. In our new Earth Indicator column, we’ll pick a number from the many floating around in the science or popular press, unpack where it came from, and explain what it means. Also, a tip of the hat to NPR’s Planet Money team. They have a Planet Money indicator on their podcast that we like so much we decided to steal the name.

Share and Share Alike

April 10th, 2012 by Paul Przyborski

The vast majority of content on the Earth Observatory is free and available for anyone to use, commercially or otherwise. Many iPhone users will recognize our Blue Marble image from their welcome screen, and many other people have been using our RSS feeds and other syndication methods to bring EO content to other websites, or to integrate into their Google homepage or Facebook feed.

Recently, we learned about a widget created for WordPress that will show our Image of the Day in your blog’s sidebar. We are always excited to see our content repurposed, and this is a really cool way for people to share compelling images and stories with their family, friends, and community.

Do you know of other places where EO content is being used? Are you a fellow developer interested in how you can use our content in your own web applications? Leave us a note here telling us where you have seen our content, or what you would do with with the resources available. Are you working on a great app, but don’t have exactly what you need? Tell us what you’re looking for! We are always looking for new ways to get our readership involved in making the Earth Observatory even better.