This image contains the initial, informal names being used by the New Horizons team for the features on Pluto’s largest moon, Charon. Names were selected based on the input the team received from the Our Pluto naming campaign. Names have not yet been approved by the International Astronomical Union (IAU). Click for a pdf. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
A big smile. That was my reaction to seeing the names of Uhura, Spock, Kirk and Sulu on the latest map of Pluto’s jumbo moon Charon. The monikers are still only informal, but new maps of Charon and Pluto submitted to the IAU for approval feature some of our favorite real life and sci-fi characters. Come on — Vader Crater? How cool is that?
This image contains the initial, informal names being used by the New Horizons team for the features and regions on the surface of Pluto. The IAU will still need to give final approval. Click for a large pdf file. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
Pluto’s features, in contrast, are named for both real people and places as well as mythological beings of underworld mythology. Clyde Tombaugh, the dwarf world’s discoverer, takes center stage, with his name appropriately spanning 990 miles (1,590 km) of frozen terrain nicknamed the “heart of Pluto”. Perhaps the most intriguing region of Pluto, it’s home to what appear to be glaciers of nitrogen ice still mobile at temperatures around –390°F (–234°C).
A close-up slice of Plutonian landscape centered on Tombaugh Regio with informal names waiting for approval. Click for a large pdf file. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
Pluto, being a physically, historically and emotionally bigger deal than Charon, comes with six themes. I’ve listed a few examples for each:
* Space Missions and Spacecraft – Sputnik, Voyager, Challenger
* Scientists and Engineers– Tombaugh, Lowell, Burney (after Venetia Burney, the young girl who named Pluto) * Historic Explorers– Norgay, Cousteau, Isabella Bird
* Underworld Beings– Cthulu, Balrog (from Lord of the Rings), Anubis (Egyptian god associated with the afterlife)
* Underworlds and Underworld Locales– Tartarus (Greek “pit of lost souls”), Xibalba (Mayan underworld), Pandemonium (capital of hell in Paradise Lost)
* Travelers to the Underworld– Virgil (tour guide in Dante’s Divine Comedy), Sun Wukong (Monkey king of Chinese mythology), Inanna (ancient Sumerian goddess)
Global map of Pluto’s moon Charon pieced together from images taken at different resolutions. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
There’s nothing like a name. Not only do names make sure we’re all talking about the same thing, but they’re how we begin to understand the unique landscapes presented to us by Pluto and its wonderful system of satellites. To keep them all straight, astronomers at the International Astronomical Union’s Working Group on Planetary System Nomemclature are charged with choosing themes for each planet, asteroid or moon along with individual names for craters, canyons, mountains, volcanoes based on those themes. Astronomers help the group by providing suggested themes and names. In the case of the Pluto system, the public joined in to help the astronomers by participating in the Our Pluto Naming Campaign.
Craters and fissures (fossae) on Charon photographed during the flyby. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
If you’ve followed naming conventions over the years, you’ve noticed more Latin in use, especially when it comes to basic land forms. I took Latin in college and loved it, but since few of us speak the ancient language anymore, we’re often at a loss to understand what’s being described. What’s a ‘Krun Macula’ or ‘Soyuz Colles’?
Image I dug out of New Horizon’s LORRI archive shows Pluto’s nitrogen ice flows in Tombaugh Regio also shows several clumps of “colles”. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
The first name is the proper name, so Krun denotes the Mandean god of the underworld. The second name – in Latin – describes the land form. Here’s a list of terms to help you translate the Plutonian and Charonian landscapes (plurals in parentheses):
Regio (Regi): Region
Mons (Montes): Mountain
Collis (Colles): Hill
Chasma (Chasmae): Canyon
Terra (Terrae): Land
Fossa (Fossae): Depression or fissure
Macula (Maculae): Spot
Valles (Valles): Valley
Rupes (Rupes): Cliff
Linea (Linea): Line
Dorsum (Dorsa): Wrinkle ridge
Cavus (Cava): Cavity or pit
Another LORRI photo showing icy Tombaugh Regio butting up against rugged, mountainous (montes) terrain. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
A view of the Villarrica Volcano's Eruption In Chile on March 3, 2-15. Credit: Ariel Marinkovic/EPA /Landov.
Want some volcano facts? Here are 10 interesting facts about volcanoes. Some of these facts you’ll know, and others may surprise you. Whatever the case, volcanoes are amazing features of nature that demand our respect.
1. There are Three Major Kinds of Volcanoes:
Although volcanoes are all made from hot magma reaching the surface of the Earth and erupting, there are different kinds. Shield volcanoes have lava flows with low viscosity that flow dozens of kilometers; this makes them very wide with smoothly sloping flanks.
Stratovolcanoes are made up of different kinds of lava, and eruptions of ash and rock and grow to enormous heights. Cinder cone volcanoes are usually smaller, and come from short-lived eruptions that only make a cone about 400 meters high.
2. Volcanoes Erupt Because of Escaping Magma:
About 30 km beneath your feet is the Earth’s mantle. It’s a region of superhot rock that extends down to the Earth’s core. This region is so hot that molten rock can squeeze out and form giant bubbles of liquid rock called magma chambers. This magma is lighter than the surrounding rock, so it rises up, finding cracks and weakness in the Earth’s crust.
Lava fountain in Hawaii. Image Credit: Jim D. Griggs/HVO/USGS
When it finally reaches the surface, it erupts out of the ground as lava, ash, volcanic gasses and rock. It’s called magma when it’s under the ground, and lava when it erupts onto the surface.
3. Volcanoes can be Active, Dormant or Extinct:
An active volcano is one that has had an eruption in historical times (in the last few thousand years). A dormant volcano is one that has erupted in historical times and has the potential to erupt again, it just hasn’t erupted recently. An extinct volcano is one that scientists think probably won’t erupt again. Here’s more information on the active volcanoes in the world.
4. Volcanoes can Grow Quickly:
Although some volcanoes can take thousands of years to form, others can grow overnight. For example, the cinder cone volcano Paricutin appeared in a Mexican cornfield on February 20, 1943. Within a week it was 5 stories tall, and by the end of a year it had grown to more than 336 meters tall. It ended its grown in 1952, at a height of 424 meters. By geology standards, that’s pretty quick.
Detailed view from space of the ash plume caused by the Eyjafjallajökull volcano in 2010. Credit: NASA
5. There are 20 Volcanoes Erupting Right Now:
Somewhere, around the world, there are likely about 20 active volcanoes erupting as you’re reading this. Some are experiencing new activity, others are ongoing. Between 50-70 volcanoes erupted last year, and 160 were active in the last decade. Geologists estimate that 1,300 erupted in the last 10,000 years.
Three quarters of all eruptions happen underneath the ocean, and most are actively erupting and no geologist knows about it at all. One of the reasons is that volcanoes occur at the mid ocean ridges, where the ocean’s plates are spreading apart. If you add the underwater volcanoes, you get an estimate that there are a total of about 6,000 volcanoes that have erupted in the last 10,000 years.
6. Volcanoes are Dangerous:
But then you knew that. Some of the most deadly volcanoes include Krakatoa, which erupted in 1883, releasing a tsunami that killed 36,000 people. When Vesuvius exploded in AD 79, it buried the towns of Pompeii and Herculaneum, killing 16,000 people.
Image of Mt. Vesuvius, captured in 2000 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) aboard the Terra satellite. Credit: NASA/EO
Mount Pelee, on the island of Martinique destroyed a town with 30,000 people in 1902. The most dangerous aspect of volcanoes are the deadly pyroclastic flows that blast down the side of a volcano during an eruption. These contain ash, rock and water moving hundreds of kilometers an hour, and hotter than 1,000 degrees C.
7. Supervolcanoes are Really Dangerous:
Geologists measure volcano eruptions using the Volcano Explosivity Index, which measures the amount of material released. A “small” eruption like Mount St. Helens was a 5 out of 8, releasing a cubic kilometer of material. The largest explosion on record was Toba, thought to have erupted 73,000 years ago.
It released more than 1,000 cubic kilometers of material, and created a caldera 100 km long and 30 kilometers wide. The explosion plunged the world into a world wide ice age. Toba was considered an 8 on the VEI.
8. The Tallest Volcano in the Solar System isn’t on Earth:
That’s right, the tallest volcano in the Solar System isn’t on Earth at all, but on Mars. Olympus Mons, on Mars, is a giant shield volcano that rises to an elevation of 27 km, and it measures 550 km across. Scientists think that Olympus Mons was able to get so large because there aren’t any plate tectonics on Mars. A single hotspot was able to bubble away for billions of years, building the volcano up bigger and bigger.
Mauna Kea observed from space. Credit: NASA/EO
9. The Tallest and Biggest Volcanoes on Earth are side by side:
The tallest volcano on Earth is Hawaii’s Mauna Kea, with an elevation of 4,207 meters. It’s only a little bigger than the largest volcano on Earth, Mauna Loa with an elevation of only 4,169 meters. Both are shield volcanoes that rise up from the bottom of the ocean. If you could measure Mauna Kea from the base of the ocean to its peak, you’d get a true height of 10,203 meters (and that’s bigger than Mount Everest).
10. The Most Distant Point from the Center of the Earth is a Volcano:
You might think that the peak of Mount Everest is the most distant point from the center of the Earth, but that’s not true. Instead, it’s the volcano Chimborazo in Ecuador. That’s because the Earth is spinning in space and is flattened out. Points at the equator are further from the center of the Earth than the poles. And Chimborazo is very close to the Earth’s equator.
Earth's Hadean Eon is a bit of a mystery to us, because geologic evidence from that time is scarce. Researchers at the Australian National University have used tiny zircon grains to get a better picture of early Earth. Credit: NASA
During the Hadean Eon, some 4.5 billion years ago, the world was a much different place than it is today. As the name Hades would suggest (Greek for “underworld”), it was a hellish period for Earth, marked by intense volcanism and intense meteoric impacts. It was also during this time that outgassing and volcanic activity produced the primordial atmosphere composed of carbon dioxide, hydrogen and water vapor.
Little of this primordial atmosphere remains, and geothermal evidence suggests that the Earth’s atmosphere may have been completely obliterated at least twice since its formation more than 4 billion years ago. Until recently, scientists were uncertain as to what could have caused this loss.
But a new study from MIT, Hebrew Univeristy, and Caltech indicates that the intense bombardment of meteorites in this period may have been responsible.
This meteoric bombardment would have taken place at around the same time that the Moon was formed. The intense bombardment of space rocks would have kicked up clouds of gas with enough force to permanent eject the atmosphere into space. Such impacts may have also blasted other planets, and even peeled away the atmospheres of Venus and Mars.
In fact, the researchers found that small planetesimals may be much more effective than large impactors – such as Theia, whose collision with Earth is believed to have formed the Moon – in driving atmospheric loss. Based on their calculations, it would take a giant impact to disperse most of the atmosphere; but taken together, many small impacts would have the same effect.
Artist’s concept of a collision between proto-Earth and Theia, believed to happened 4.5 billion years ago. Credit: NASA
Hilke Schlichting, an assistant professor in MIT’s Department of Earth, Atmospheric and Planetary Sciences, says understanding the drivers of Earth’s ancient atmosphere may help scientists to identify the early planetary conditions that encouraged life to form.
“[This finding] sets a very different initial condition for what the early Earth’s atmosphere was most likely like,” Schlichting says. “It gives us a new starting point for trying to understand what was the composition of the atmosphere, and what were the conditions for developing life.”
What’s more, the group examined how much atmosphere was retained and lost following impacts with giant, Mars-sized and larger bodies and with smaller impactors measuring 25 kilometers or less.
What they found was that a collision with an impactor as massive as Mars would have the necessary effect of generating a massive a shockwave through the Earth’s interior and potentially ejecting a significant fraction of the planet’s atmosphere.
However, the researchers determined that such an impact was not likely to have occurred, since it would have turned Earth’s interior into a homogenous slurry. Given the appearance of diverse elements observed within the Earth’s interior, such an event does not appear to have happened in the past.
A series of smaller impactors, by contrast, would generate an explosion of sorts, releasing a plume of debris and gas. The largest of these impactors would be forceful enough to eject all gas from the atmosphere immediately above the impact zone. Only a fraction of this atmosphere would be lost following smaller impacts, but the team estimates that tens of thousands of small impactors could have pulled it off.
Artist’s concept of the early Earth, showing a surface pummeled by large impacts. Credit: Simone Marchi
Such a scenario did likely occur 4.5 billion years ago during the Hadean Eon. This period was one of galactic chaos, as hundreds of thousands of space rocks whirled around the solar system and many are believed to have collided with Earth.
“For sure, we did have all these smaller impactors back then,” Schlichting says. “One small impact cannot get rid of most of the atmosphere, but collectively, they’re much more efficient than giant impacts, and could easily eject all the Earth’s atmosphere.”
However, Schlichting and her team realized that the sum effect of small impacts may be too efficient at driving atmospheric loss. Other scientists have measured the atmospheric composition of Earth compared with Venus and Mars; and compared to Venus, Earth’s noble gases have been depleted 100-fold. If these planets had been exposed to the same blitz of small impactors in their early history, then Venus would have no atmosphere today.
She and her colleagues went back over the small-impactor scenario to try and account for this difference in planetary atmospheres. Based on further calculations, the team identified an interesting effect: Once half a planet’s atmosphere has been lost, it becomes much easier for small impactors to eject the rest of the gas.
The researchers calculated that Venus’ atmosphere would only have to start out slightly more massive than Earth’s in order for small impactors to erode the first half of the Earth’s atmosphere, while keeping Venus’ intact. From that point, Schlichting describes the phenomenon as a “runaway process — once you manage to get rid of the first half, the second half is even easier.”
This gave rise to another important question: What eventually replaced Earth’s atmosphere? Upon further calculations, Schlichting and her team found the same impactors that ejected gas also may have introduced new gases, or volatiles.
“When an impact happens, it melts the planetesimal, and its volatiles can go into the atmosphere,” Schlichting says. “They not only can deplete, but replenish part of the atmosphere.”
The “impact farm:, an area on Venus marked by impact craters and volcanic activity. Credit: NASA/JPL
The group calculated the amount of volatiles that may be released by a rock of a given composition and mass, and found that a significant portion of the atmosphere may have been replenished by the impact of tens of thousands of space rocks.
“Our numbers are realistic, given what we know about the volatile content of the different rocks we have,” Schlichting notes.
Jay Melosh, a professor of earth, atmospheric, and planetary sciences at Purdue University, says Schlichting’s conclusion is a surprising one, as most scientists have assumed the Earth’s atmosphere was obliterated by a single, giant impact. Other theories, he says, invoke a strong flux of ultraviolet radiation from the sun, as well as an “unusually active solar wind.”
“How the Earth lost its primordial atmosphere has been a longstanding problem, and this paper goes a long way toward solving this enigma,” says Melosh, who did not contribute to the research. “Life got started on Earth about this time, and so answering the question about how the atmosphere was lost tells us about what might have kicked off the origin of life.”
Going forward, Schlichting hopes to examine more closely the conditions underlying Earth’s early formation, including the interplay between the release of volatiles from small impactors and from Earth’s ancient magma ocean.
“We want to connect these geophysical processes to determine what was the most likely composition of the atmosphere at time zero, when the Earth just formed, and hopefully identify conditions for the evolution of life,” Schlichting says.
Schlichting and her colleagues have published their results in the February edition of the journal Icarus.
A 3-D model of 6 Hebe based on its light curve. The asteroid is about 120 miles in diameter and orbits in the main asteroid belt between Mars and Jupiter. Credit: Charles University_Josef Durech_Vojtech Sidorin
In the reeds that line the banks of the celestial river Eridanus, you’ll find Hebe on the prowl this month. Discovered in 1847 by German amateur astronomer Karl Ludwig Hencke , the asteroid may hold the key to the origin of the H-chondrites, a large class of metal-rich stony meteorites found in numerous amateur and professional collections around the world. You can now see this interesting minor planet with nothing more than a pair of binoculars or small telescope.
Judging by his demeanor, it might have been unwise to tell Karl Hencke he was wasting his time looking for asteroids.
The first four asteroids – Ceres, Pallas, Juno and Vesta – were discovered in quick succession from 1801 to 1807. Then nothing turned up for years. Most astronomers wrongly assumed all the asteroids had been found and moved on to other projects like measuring the orbits of double stars and determining stellar parallaxes. Nothing could have been further from the truth. Hencke, who worked as a postmaster during the day, doggedly persisted in sieving the stars for new asteroids in his free time at night. His systematic search began in 1830. Fifteen years and hundreds of cold nights at the eyepiece later he turned up 5 Astrae (asteroid no. 5) on Dec. 8, 1845, and 6 Hebe on July 1, 1847.
Hebe orbits in the main asteroid belt between Mars and Jupiter with an average distance from the Sun of 225 million miles. It spins on its axis once every 7.3 hours. Credit: Wikipedia
Energized by the finds, astronomers returned to their telescopes with renewed gusto to join in the hunt once again. The rest is history. As of November 2014 there are 415,688 numbered asteroids and a nearly equal number of unnumbered discoveries. Fittingly, asteroid 2005 Hencke honors the man who kept the fire burning.
You’ll find Hebe trucking along in Eridanus this month just north of Delta (left) and Epsilon Eridani, a pair of +3.5 magnitude stars. This map shows stars to magnitude +9.5 with Hebe’s position marked every 5 nights. Click to enlarge. Source: Chris Marriott’s SkyMap software
At 120 miles (190 km) across, Hebe is one of the bigger asteroids (officially 33rd in size in the main belt) and orbits the Sun once every 3.8 years. It will be our guest this final month of the year shining at magnitude +8.2 in early December, +8.5 by mid-month and +8.9 when you don your party hat on New Year’s Eve. All the while, Hebe will loop across the barrens of Eridanus west of Orion. Use the maps here to help track it down. I’ve included a detailed color map above, but also created a “black stars on white” version for those that find reverse charts easier to use.
Use this wide view of the sky to get oriented before zeroing in with the more detailed map above. Hebe lies just a few degrees north of Delta and Epsilon Eridani for much of December. Best viewing time is from 10 p.m. to 2 a.m. local time early in the month. Source: Stellarium
In more recent times, Hebe’s story takes an interesting turn. Through a study of its gravitational nudges on other asteroids, astronomers discovered that Hebe is a very compact, rocky object, not a loosey-goosey pile of rubble like some asteroids. Its high density provides strong evidence for a composition of both rock and iron. Scientists can determine the approximate composition of an asteroid’s surface by studying its reflectance spectrum, or what colors or wavelengths are reflected back from the object after a portion is absorbed by its surface. They use infrared light because different minerals absorb different wavelengths of infrared light. That data is compared to infrared absorptions from rocks and meteorites found on Earth. Turns out, our friend Hebe’s spectrum is a good match to two classes of meteorites – the H-chondrites, which comprise 40% of known meteorites – and the rarer IIE silicated iron meteorites.
Did this slice of meteorite come from Hebe? A 12.9-gram specimen of NWA 2710, an H5 stony chondrite, sparkles in the light. The shiny flecks are iron-nickel metal set in a stony matrix. Credit: Bob King
Because Hebe orbits close to an unstable zone in the asteroid belt, any impacts it suffers are soon perturbed by Jupiter’s gravity and launched into trajectories than can include the Earth. When you spot Hebe in your binoculars the next clear night, you might just be seeing where many of the more common space rocks in our collections originated.
Which is the main culprit for the terminal Cretaceous extinction: the Chicxulub impact or Deccan Traps volcanism? Upper Image: Donald Davis, NASA JPL
Lower Image: USGS
About sixty five and a half million years ago, the Earth suffered its largest known cosmic impact. An asteroid or comet nucleus about 10 km in diameter slammed into what is now the Yucatan peninsula of Mexico. It gouged out a crater 180 to 200 km in diameter: nearly twice as large as the prominent crater Copernicus on Earth’s moon. But did this impact really cause the extinction of the dinosaurs and many other forms of life? Many earth scientists are convinced that it did, but some harbor nagging doubts. The doubters have marshaled a growing body of evidence for another culprit; the enormous volcanic eruptions that produced the Deccan Traps formation in India. The skeptics recently presented their case at a meeting of the Geological Society of America in Vancouver, Canada, on October 19.
The dinosaurs are the most well-known victims of the mass extinction event that ended the Cretaceous period. The extinction claimed almost all large vertebrates on land, at sea, or in the air, as well as numerous species of insects, plants, and aquatic invertebrates. At least 75% of all species then existing on Earth vanished in a short span in relation to the geological timescale of millions of years. The disaster is one of five global mass extinction events that paleontologists have identified over the tenure of complex life on Earth.
The hypothesis that the terminal Cretaceous extinction was caused by a cosmic impact has been the most popular explanation of this catastrophe among earth scientists and the public for several decades. It was proposed in 1980 by the father and son team of Luis and Walter Alvarez and their collaborators. The Alvarez team’s main line of evidence that an impact happened was an enrichment of the metal iridium in sediments dating roughly to the end of the Cretaceous. Iridium is rare in Earth’s crust, but common in meteorites. The link between iridium and impacts was first established by studies of the samples returned by the Apollo astronauts from the Moon.
Over the ensuing decades, evidence of an impact accumulated. In 1991, a team of scientists led by Dr. Alan Hildebrand of the Department of Planetary Sciences at Arizona University, published evidence of a gigantic buried impact crater, called Chicxulub, in Mexico. Other investigators found evidence of materials ejected by the impact, including glass spherules in Haiti and Mexico. Supporters of the impact hypothesis believe that vast amounts of dust hurtled into the stratosphere would have plunged the surface of the planet into the darkness and bitter cold of an “impact winter” lasting for at least months, and perhaps decades. Global ecosystems would have collapsed and mass extinction ensued. But, they’ve had a harder time finding evidence for these consequences than for the impact itself.
Doubters of the Alvarez hypothesis don’t question the ‘smoking gun’ evidence that an impact happened near the end of the Cretaceous, but they don’t think it was the main cause of the extinctions. For one thing, inferring the exact time of the impact from its putative geological traces has proved difficult. Dr. Gerta Keller of the Department of Geosciences of Princeton University, a prominent skeptic of the Alvarez hypothesis, has questioned estimates that make the impact and the extinctions simultaneous. Analyzing core samples taken from the Chicxulub crater, and glass spherule containing deposits in northeastern Mexico, she concludes that the Chicxulub impact preceded the mass extinction by 120,000 years and had little consequence for the fossil record of life in the geological formations which she studied. Of the five major mass extinction events in Earth’s history, she noted in a 2011 paper, none other than the terminal Cretaceous event has ever been even approximately associated with an impact. Several other large impact craters besides Chicxulub have been well studied by geologists and none is associated with fossil evidence of extinctions. On the other hand, four of the five major mass extinctions appear to have some connection with volcanic eruptions.
Keller and other Alvarez skeptics look to a major volcanic event that occurred towards the end of the Cretaceous as an alternate primary cause of the extinction. The Deccan Traps formation in central India is a plateau consisting of multiple layers of solidified lava 3500 m thick. Today, it extends over an area larger than all of France. It was once three times that large. It was formed in a series of three volcanic outbursts that may have been among the largest in Earth’s history. At the October conference, Dr. Theirry Adatte of the Institute of Earth Sciences at the University of Lausanne in France presented evidence that the second of these outbursts was by far the largest, and occurred over a period of 250,000 years prior to the end of the Cretaceous. During this period, 80% of the total lava thickness of the Deccan formation was deposited. The eruptions produced lava flows that may be the longest on Earth, extending more than 1500 km.
The blue area indicates the Deccan Traps, a massive remnant of immense volcanic eruptions at the end of the Cretaceous period that may have contributed to the terminal Cretaceous extinction. Credit: CamArchGrad, English Wikipedia Project
To illustrate the likely environmental consequences of such a super-eruption, Adatte invoked the worst volcanic catastrophe in human history. Over eight months from 1783-84 a major eruption in Laki, Iceland, deposited 14.3 square kilometers of lava and emitted an estimated 122 megatons of toxic sulfur dioxide into the atmosphere. About a quarter of the people and half of the livestock in Iceland died. Across Europe the sky was darkened by a pall of haze, and acid rain fell. Europe and America experienced the most severe winter in history and global climate was disrupted for a decade. Millions of people died from the resulting drought and famine. The Laki incident was nonetheless miniscule by comparison with the second Deccan Traps outburst, which produced 1.5 million square kilometers of lava and an estimated 6,500- 17,000 gigatons of sulfur dioxide.
The Deccan Traps eruptions would also have emitted immense quantities of carbon dioxide. Carbon dioxide is a heat trapping greenhouse gas responsible for the oven-like temperatures of the planet Venus. It is released by the burning of fossil fuels and plays a major role in human-caused global warming on Earth. Thus Geller surmised that the Deccan Traps eruptions could have produced both periods of intense cold due to sulfur dioxide haze, and intense heat due to carbon dioxide induced global warming.
At the October conference she presented the results of her studies of geological formations in Tunisia that preserved a high resolution record of climate change during the time of the main pulse of Deccan Traps volcanic activity. Her evidence shows that near the onset of the 250,000 year pulse, there was a ‘hyperthermal’ period of rapid warming that increased ocean temperatures by 3-4 degrees Celsius. She claimed that temperatures remained elevated through the pulse culminating with a second ‘hyperthermal’ warming of the oceans by an additional 4-5 degrees Celsius. This second hyperthermal warming occurred within a 10,000 year period of mega-eruptions, which corresponded with the terminal Cretaceous extinction. The Chicxulub impact occurred during the 250,000 year pulse, but well prior to the extinctions and the hyperthermal event.
The debate over the relative importance of the Chicxulub impact and the Deccan Trap volcanoes in producing the terminal Cretaceous extinction isn’t over. In May of this year, a team headed by Dr. Johan Vellekoop at the Department of Earth Sciences at Ulrecht University in the Netherlands published evidence of a geologically brief episode of cooling which they claim as the first direct evidence of an “impact winter”. Whatever the outcome of the debate, it seems clear that the end of the Cretaceous, with its super-volcanoes and giant impacts, was not a good time for life on Earth.
G. Keller (2012), The Cretaceous-Tertiary Mass Extinction, Chicxulub Impact, and Deccan Volcanism, Earth and Life, J.A. Talent, Editor, Springer Science and Business media.
The feature called Maskelyne is one of many newly discovered young volcanic deposits on the moon. Called irregular mare patches, these areas are thought to be remnants of small lava eruptions that occurred recently in the moon's past. To view this image correctly, the large, dark, circular feature right of center is pancake-like dome that rises ABOVE the surrounding lighter-toned terrain. Lower domes, many pitted with small craters, are seen from left to right across the photo. Credit: NASA/GSFC/Arizona State University
The Moon’s a very dusty museum where the exhibits haven’t changed much over the last 4 billion years. Or so we thought. NASA’s Lunar Reconnaissance Orbiter (LRO) has provided researchers strong evidence the Moon’s volcanic activity slowed gradually instead of stopping abruptly a billion years ago.
Some volcanic deposits are estimated to be 100 million years old, meaning the moon was spouting lava when dinosaurs of the Cretaceous era were busy swatting giant dragonflies. There are even hints of 50-million-year-old volcanism, practically yesterday by lunar standards.
Ina Caldera sits atop a low, broad volcanic dome or shield volcano, where lavas once oozed from the moon’s crust. The darker patches in the photo are blobs of older lunar crust. As in the photo of Maskelyne, they form a series of low mounds higher than the younger, jumbled terrain around them. Credit: NASA
The deposits are scattered across the Moon’s dark volcanic plains (lunar “seas”) and are characterized by a mixture of smooth, rounded, shallow mounds next to patches of rough, blocky terrain. Because of this combination of textures, the researchers refer to these unusual areas as “irregular mare patches.”
Measuring less than one-third mile (1/2 km) across, almost all are too small to see from Earth with the exception of Ina Caldera, a 2-mile-long D-shaped patch where blobs of older, crater-pitted lunar crust (darker blobs) rise some 250 feet above the younger, rubbly surface like melted cheese on pizza.
Lavas on the moon were thin and runny like this flow photographed in Kilauea, Hawaii. Credit: USGS
Ina was thought to be a one-of-a-kind until researchers from Arizona State University in Tempe and Westfälische Wilhelms-Universität Münster in Germany spotted 70 more patches in close-up photos taken by the LRO. The large number and the fact that the patches are scattered all over the nearside of the Moon means that volcanic activity was not only recent but widespread.
Astronomers estimate ages for features on the moon by counting crater numbers and sizes (the fewer seen, the younger the surface) and the steepness of the slopes running from the tops of the smoother domes to the rough terrain below (the steeper, the younger).
“Based on a technique that links such crater measurements to the ages of Apollo and Luna samples, three of the irregular mare patches are thought to be less than 100 million years old, and perhaps less than 50 million years old in the case of Ina,” according to the NASA press release.
Artist concept illustration of the internal structure of the moon. Credit: NOAJ
The young mare patches stand in stark contrast to the ancient volcanic terrain surrounding them that dates from 3.5 to 1 billion years ago.
For lava to flow you need a hot mantle, the deep layer of rock beneath the crust that extends to the Moon’s metal core. And a hot mantle means a core that’s still cranking out a lot of heat.
Scientists thought the Moon had cooled off a billion or more years ago, making recent flows all but impossible. Apparently the moon’s interior remained piping hot far longer than anyone had supposed.
“The existence and age of the irregular mare patches tell us that the lunar mantle had to remain hot enough to provide magma for the small-volume eruptions that created these unusual young features,” said Sarah Braden, a recent Arizona State University graduate and the lead author of the study.
It takes two to tango. The moon’s gravity raises a pair of watery bulges in the Earth’s oceans creating the tides, while Earth’s gravity stretches and compresses the moon to warm its interior. Illustration: Bob King
One way to keep the Moon warm is through tidal interaction with the Earth. A recent study points out that strains caused by Earth’s gravitational tug on the Moon (nearside vs. farside) heats up its interior. Could this be the source of the relatively recent lava flows?
So the pendulum swings. Prior to 1950 it was thought that lunar craters and landforms were all produced by volcanic activity. But the size and global distribution of craters – and the volcanoes required to produce them – would be impossible on a small body like the Moon. In the 1950s and beyond, astronomers came to realize through the study of nuclear bomb tests and high-velocity impact experiments that explosive impacts from asteroids large and small were responsible for the Moon’s craters.
This latest revelation gives us a more nuanced view of how volcanism may continue to play a role in the formation of lunar features.
The Moon sets above the Continental Divide in Colorado from 86,000 feet. Taken June 27, 2013 on a meteorological balloon launched from Boulder, Colorado. Credit and copyright: Patrick Cullis.
What physical evidence exists of a huge collision that formed our Moon and nearly blew the Earth apart, about 4.5 billion years ago? This is the leading theory for how the Moon came to be, but given it happened so long ago the physical evidence is scarce.
Readers may recall the story from last week talking about how oxygen in Moon rocks shows evidence of this crash. This week, there’s a new study from the same conference that focuses on the other side of the puzzle piece: what can we see on planet Earth? Turns out there might be a “signal” showing us the way.
As the theory goes, the colliding body — which some researchers call “Theia” — would have created a cloud of fragments surrounding our planet that eventually coalesced into the Moon.
The new research says that evidence of this collision would have showed up in the mantle, a layer of the Earth’s interior, and could explain a puzzling difference in isotopes (types) of certain elements that was known before.
“The energy released by the impact between the Earth and Theia would have been huge, certainly enough to melt the whole planet,” stated research lead Sujoy Mukhopadhyay, an associate professor at Harvard University.
Layers of the Earth
“But we believe that the impact energy was not evenly distributed throughout the ancient Earth. This means that a major part of the impacted hemisphere would probably have been completely vaporized, but the opposite hemisphere would have been partly shielded, and would not have undergone complete melting.”
The team said that the impact did not completely stir the mantle, which would explain why the ratio of isotopes of helium and nitrogen inside the shallow part of the mantle is much higher than the deep mantle.
They also analyzed two isotopes of xenon. Scientists know already that the material on the surface has a lower isotope ratio to what is inside, but what is new is comparing these isotopes pointed to an age of the collision: about 100 million years after the Earth formed.
The research was presented today at the Goldschmidt conference in Sacramento, California.
First ever image of Earth Taken by Mars Color Camera aboard India’s Mars Orbiter Mission (MOM) spacecraft while orbiting Earth and before the Trans Mars Insertion firing on Dec. 1, 2013. Image is focused on the Indian subcontinent. Credit: ISRO
While astronomers are trying to figure out which planets they find are habitable, there are a range of things to consider. How close are they to their parent star? What are their atmospheres made of? And once those answers are figured out, here’s something else to wonder about: how many minerals are on the planet’s surface?
As more information is learned about these distant worlds, it will be interesting to see if it’s possible to apply his findings — if we could detect the minerals from afar in the first place.
“We live on a planet of remarkable beauty, and when you look at it from the proximity of our moon, you see what is obviously a very dynamic planet,” Hazen told delegates at “Habitable Worlds Across Time and Space”, a spring symposium from the Space Telescope Science Institute that is being webcast this week (April 28-May 1).
His point was that planets don’t necessarily start out that way, but he said in his talk that he’d invite comments and questions on his work for alternative processes. His team believes that minerals and life co-evolved: life became more complex and the number of minerals increased over time.
Artist’s impression of a baby star still surrounded by a protoplanetary disc in which planets are forming. Credit: ESO
The first mineral in the cosmos was likely diamonds, which were formed in supernovas. These star explosions are where the heavier elements in our cosmos were created, making the universe more rich than its initial soup of hydrogen and helium.
There are in fact 10 elements that were key in the Earth’s formation, Hazen said, as well as that of other planets in our solar system (which also means that presumably these would apply to exoplanets). These were carbon, nitrogen, oxygen, magnesium, silicon, carbon, titanium, iron and nitrogen,which formed about a dozen minerals on the early Earth.
Here’s the thing, though. Today there are more than 4,900 minerals on Earth that are formed from 72 essential elements. Quite a change.
Hazen’s group proposes 10 stages of evolution:
Primary chondrite minerals (4.56 billion years ago) – what was around as the solar nebula that formed our solar system cooled. 60 mineral species at this time.
Planetesimals — or protoplanets — changed by impacts (4.56 BYA to 4.55 BYA). Here is where feldspars, micas, clays and quartz arose. 250 mineral species.
Planet formation (4.55 BYA to 3.5 BYA). On a “dry” planet like Mercury, evolution stopped at about 300 mineral species, while “wetter” planets like Mars would have seen about 420 mineral species that includes hydroxides and clays produced from processes such as volcanism and ices.
Granite formation (more than 3.5 BYA). 1,000 mineral species including beryl and tantalite.
Plate tectonics (more than 3 BYA). 1,500 mineral species. Increases produced from changes such as new types of volcanism and high-pressure metamorphic changes inside the Earth.
The official poster of the World Space Week Association 2013 campaign. Credit: World Space Week Association
These stages above are about as far as you would get on a planet without life, Hazen said. As for the remaining stages on Earth, here they are:
Anoxic biosphere (4 to 2.5 BYA), again with about 1,500 mineral species existing in the early atmosphere. Here was the rise of chemolithoautotrophs, or life that obtains energy from oxidizing inorganic compounds.
Paleoproterozoic oxidation (2.5 to 1.5 BYA) — a huge rise in mineral species to 4,500 as oxygen becomes a dominant player in the atmosphere. “We’re trying to understand if this is really true for every other planet, or if there is alternative pathways,” Hazen said.
And the final three stages up to the present day was the emergence of large oceans, a global ice age and then (in the past 540 million years or so) biomineralization or the process of living organisms producing minerals. This latter stage included the development of tree roots, which led to species such as fungi, microbes and worms.
‘The Moon rising behind a couple of palm trees with cows grazing in the foreground. As you can see in the image, the bottom half of the moon has a different tint due to the earths atmosphere.’ Credit: Tom Connor, Parrish, FL
It should be noted here that oxygen does not necessarily indicate there is complex life. Fellow speaker David Catling from the University of Washington, however, noted that oxygen rose in the atmosphere about 2.4 billion years ago, coincident with the emergence of complex life.
Animals as we understand them could have been “impossible for most of Earth’s history because they couldn’t breathe,” he noted. But more study will be needed on this point. After all, we’ve only found life on one planet: Earth.
An erupting undersea volcano forms a new island off the coast of Nishinoshima, a small unihabited island in the southern Ogasawara chain of islands. The image was taken on November 21, 2013 by the Japanese Coast Guard.
A volcanic eruption is creating a tiny new island off the coast of Japan. The Japanese Coast Guard snapped images and video of the eruption taking place, showing the new island being formed. Footage showed heavy smoke, ash and rocks spewing from the volcanic crater. As of this writing, experts say the small island is about 200 meters (660 feet) in diameter. It is located just off the coast of Nishinoshima, a small, uninhabited island in the Ogasawara chain, also known as the Bonin Islands, about about 620 miles (1,000 km) south of Tokyo.
See a video and additional images below.
Only time will tell if the island will remain or if the ocean waters will reclaim it. According to Yahoo News, Japan’s chief government spokesman said they would welcome any new territory.
“This has happened before and in some cases the islands disappeared,” Yoshihide Suga said when asked if the government was planning on naming the new island. “If it becomes a full-fledged island, we would be happy to have more territory.”
An erupting undersea volcano forms a new island, shown by its nearest neighbor, Nishinoshima, a small unihabited island in the southern Ogasawara chain of islands. The image was taken on November 21, 2013 by the Japanese Coast Guard.This screenshot of Google Maps shows all the volcanoes in the The Japan, Taiwan, Marianas Region. Via Google Maps and the Smithsonian volcano website.
According to the Smithsonian Global Volcanism Program website, the Japan, Taiwan, Marianas Region is a very active region in the Pacific Ring of Fire and most volcanoes in this region “result from subduction of westward-moving oceanic crust under the Asian Plate. In the Izu-Mariana chain, however, the crust to the west is also oceanic, forming more basaltic island arcs (but with volcanoes that are far more explosive than oceanic hotspot volcanoes).”
Canadian astronaut Jeremy Hansen during 2010 geology training near Gila Bend, Arizona. Credit: Canadian Space Agency
This week, Canadian astronaut Jeremy Hansen is on his way to a remote island in the Canadian Arctic. We realize this sounds like the opening episode for Survivor, but his purpose up there is more scientific: to conduct field geology.
Geology work, and training for sample collection is not as easy as simply picking up whatever you see on the ground. It’s important to get a range of rocks that represent the geology of the area. You also need to photograph and otherwise document the area in such a way that geologists can learn more about how it was formed, among other duties.
A trained observer can come to preliminary conclusions while wandering around in the field, and possibly change his or her sample-gathering strategy in accordance with that. The Apollo moon missions were replete with examples of this, with one of the more famous ones perhaps being when Harrison Schmitt (who, unlike his colleagues, had a Ph.D. in geology) stumbled across some orange soil during Apollo 17. This was probably evidence of an ancient fire-fountain of lava on the moon.
But Schmitt certainly wasn’t expecting to see that when he walked on the surface. Check out his reaction around 1:50 in this video:
Hansen will join a Western University group to study “impact cratering processes while learning methods and techniques for conducting geological fieldwork that can be applied to sites beyond our planet,” stated the Canadian Space Agency. To make it feel more space mission-like, the group will be working with limited supplies and support.
Geology training isn’t important just on the ground, but also in observing from space. As Hansen points out on this video, from time to time astronauts on the International Space Station are called upon to observe features from their orbital perches. If they understand the processes behind what they see, their descriptions, videos and photos will be more scientific.
Hansen will stay on Devon Island until about July 25, studying impact crater processes along with the rest of the team. Updates should be available on his Twitter feed as well as through the Canadian Space Agency.
And by the way, Canada was also useful to astronauts during the Apollo years. One famous geology site was at Sudbury, Ont. This website highlights the activities of the Apollo 16 crew, which was looking at craters in the area.
