When a volcano erupts, it’s spewing forth lava, ash and hot rock. But where does this material come from, and how does it get to the surface? A volcano conduit is the pipe or vent at the heart of a volcano where material wells up from beneath the surface.
The surface of the Earth is relatively cool, but things get hotter as you descend beneath the ground. When you get about 30 km down (beneath the continents), you reach the Earth’s mantle. This is region of the Earth where rocks can be heated to more than 1,000 degrees C. Because of this high heat and pressure, liquid rock squeezes out of the mantle and collects in magma chambers beneath the Earth’s crust. The magma is “lighter” than the surrounding rock, so it floats to the surface, finding its way though cracks and faults in the crust. Eventually it reaches the surface and erupts as a volcano.
The volcano conduit is the pipe that carries this magma from the magma chamber, up through the crust and through the volcano itself until it reaches the surface. Stratovolcanoes, the largest kind of volcano, can have entire networks of volcano conduits inside them, and they can have eruptions from the central crater at the top, or from volcanic vents on the side.
After an eruption, the lava can cool and harden in the volcano conduit forming a hard plug. In some cases the plug causes the volcano to build up additional pressure and have an explosive eruption. In other cases, the volcano goes extinct, and the hard plug is all that remains when the rest of the volcano erodes away. Some of the most beautiful natural structures are these volcanic necks perching up above the surroundings.
We have written many articles about volcanoes for Universe Today. Here’s an article about dormant volcanoes, and here’s an article about extinct volcanoes.
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Mount Etna is a stratovolcano on the east side of the Island of Sicily. Standing 3,329 meters tall, Etna is the second largest volcano in Europe, and the highest mountain in Italy south of the Alps. But more importantly, Mount Etna is one of the most active volcanoes in the world, in an almost constant state of eruption.
Etna is classified as a stratovolcano (also known as a composite volcano). This is where many different kinds of eruptions over time have built up the huge mountain. You can have layers of lava, rock and ash, and many volcanic vents reaching the surface and capable of erupting. Many of the largest, most dangerous volcanoes in the world are stratovolcanoes (Mount St. Helens, for example).
Geologists believe the Etna started erupting about 300,000 years ago. In the last 35,000 years or so the mountain has had many explosive eruptions with pyroclastic flows cascading down its banks. Ash from Mount Etna eruptions has been found in Rome, located 800 km away. The successive eruptions have also caused calderas on the mountain to collapse creating depressions. There are now almost constant eruptions on Etna, with severe eruptions happening every 20 years or so.
You would think that the Italians would be nervous about having an active volcano in their back yard, but people actually live on the slopes of Etna. There are vineyards and orchards spread across its flanks; that’s because the rich volcanic soil is so good for planting. For example, in 2007 an eruption brought rivers of lava flowing down the slopes of Etna into an uninhabited valley. Villagers in the city of Catania on the island of Sicily could watch the eruption. Only an airport was closed during the eruption.
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The name “volcano” comes the island of Vulcano, located in the Mediterranean Sea off the coast of Sicily. The Romans believed that Volcano was the chimney to the god Vulcan’s workshop. The island itself was thought to come from the debris that came out of the god’s furnace. The Romans believed that the earthquakes that shook the ground around the island came from Vulcan working in his shop, creating weapons for the gods to make war on one another.
The volcanic activity on the island of Vulcano comes from the northward motion of the African Plate colliding with the Eurasian Plate. This has opened up three volcanic hotspots on the island. There are two old stratovolcano cones at the southern end of the island, and then the most active Fossa cone in the center, and another at the north of the island. Currently about 470 people live on the island of Vulcano, getting their income from tourism.
In mythology, Vulcan was married to Venus, the goddess of love and beauty. The Romans believed that eruptions on Mount Etna in Sicily were caused by Vulcan’s anger at Venus. He works the forge so angrily that the metal turns red hot and sparks and smoke erupt from the top of the volcano.
Space shuttle Atlantis landed safely in California on Sunday morning after “dynamic and unpredictable” weather kept the orbiter from returning to Florida. Atlantis touched down on runway 22 of Edwards Air Force Base at 11:39 am EDT (1539 GMT) Sunday, the first of two opportunities to land the shuttle in California. Atlantis spent nearly 13 days in orbit on the STS-125 mission, successfully repairing and upgrading the Hubble Space Telescope during a series of five spacewalks. Atlantis will be ferried to Kennedy Space Center on top of a modified 747 in about a week. Next shuttle mission: STS-127, slated for liftoff on June 13, on a trip to the International Space Station.
Remembering Phoenix
Do you remember what you were doing a year ago? You may recall the Phoenix Mars lander touched down on the Red Planet a year ago, and if you were on Twitter back then, you could follow the spacecraft’s progress via the fledgling social networking device. The “voice” of Phoenix’s Twitter account, Veronica McGregor, is re-living the events of a year ago by re-posting her “Tweets” in real time as they were written a year ago. It is a fun way to stroll down memory lane.
About the same time space shuttle Atlantis’ landing was waved off today due to continued rainy weather in Florida, the White House announced that former shuttle commander Charles Bolden Jr. will be nominated as NASA’s next administrator. President Obama also chose Lori Garver to be Bolden’s deputy administrator. Obama said, “These talented individuals will help put NASA on course to boldly push the boundaries of science, aeronautics and exploration in the 21st century and ensure the long-term vibrancy of America’s space program.”
Several different sources expect Bolden to be a strong proponent of manned spaceflight, since he has flown on the shuttle four times, with over 680 hours in space. Many believe he will also be strongly in favor of the Constellation program, as well as support the efforts of some members of Congress who would like to see the life of the space shuttle extended beyond 2010.
Bolden and Garver will have to be approved by Congress, which can sometimes be a lengty process. Let’s hope not – over four months without an official administrator is long enough.
Bolden will have his work cut out for him, as NASA has a lot on its plate, but no real growth in its budget. The fiscal year 2010 budget request of $18.686 billion includes $456M increase for science and $630M increase for Exploration. Some of that increase is because of the one-time Recovery Act stimulus money. Future budget proposals for fiscal years 2011, 2012, 2013 also are also relatively flat. NASA Watch.com reported several sources say Bolden expressed concern at his meeting with President Obama because he was told that further cuts to human spaceflight in future budgets might be needed. STS-125 Commander Scott Altman (left) and pilot Greg Johnson use a software program to practice landing the shuttle. Credit: NASA
Meanwhile, the crew of STS-125 will stay on orbit another day. NASA officials are still hoping the shuttle can land at Kennedy Space Center in Florida rather than Edwards Air Force Base in California.
The astronauts will have two opportunities to land in Florida Sunday and two at Edwards. The first Florida opportunity, the astronauts would fire Atlantis’ twin braking rockets at 8:58 am EDT with landing at 10:11 am. A second Florida landing opportunity is available at 11:49 am.
Friday’s landing attempt was also canceled because of rain, low clouds and lightning. The forecast for Sunday is marginal, with clouds and rain expected, but flight controllers are hopeful conditions will improve.
Astronaut Mike Massimino in the foreground, with Mike Good on the end of the robotic arm, backdropped by the shuttle, Hubble, and Earth. Credit: NASA
In our last installment of images from the STS-125 mission, we left off with third EVA of the mission. Since then, as I’m sure you know, the astronauts have completed two more EVAs, released Hubble and are waiting for the weather to improve in Florida so they can land. So, let’s get caught up with the latest images released by NASA. I love the image above, as it has everything in it about the mission: two spacewalking astronauts from EVA #4 (Mike Massimino and Mike Good), the shuttle Atlantis, Hubble, and a beautiful view of Earth. Continue reading “More Stunning Images From the Hubble Servicing Mission”
Kids of all ages! With no Moon around to light up the weekend skies, isn’t it time to spend an evening outside an enjoy the stars? With Spring in the air in the northern hemisphere, the nights are much warmer and a welcome time to observe the glittering jewels that turn around Polaris, the “North Star”. This time we’re off on an adventure to help you identify the eight largest constellation in the night – Draco the Dragon…
As the skies get dark tonight, go out and do some stargazing. One of the brightest you will see will be almost overhead – the planet Saturn. Do you recognize the “Big Dipper” – Ursa Major – to the north? Good! Connect the dots of the two stars on the front of the dipper and they will point the way to Polaris. Once you have this star in site, you are ready to find the Draco constellation. It’s a long, glittering chain of faint stars that curls around between Ursa Major and Polaris on the east side. Watch as the night goes on and the Dragon climbs higher. By midnight its stars will have curled over the top of Polaris!
Listen… Do you hear a voice on the wind? I think it has a story for you…
“What “knight’s” tale would not be complete without a battle with a dragon? Almost every ancient culture has a dragon in its myths! These huge serpents were believed to have a body like a huge lizard, or a snake with two pairs of lizard-type legs, and able to emit fire from their mouths. Even our English word, dragon, comes from the Greek word “drakon” meaning huge serpent! Perhaps the largest of all known dragons is portrayed in stars… the constellation of Draco.”
“Finding Draco isn’t easy, but begin before dark and look to the north. As the stars come out one by one, look for a long ribbon of faint stars which encircles Polaris – the “North Star”. If you have a telescope, you can take a look into the eye of the Dragon! NGC 6543, is one of the brightest planetary nebula in the sky and you can find its small, blue green disc even with binoculars.”
“But, do dragons really breathe fire? No, but the constellation of Draco is host to six different meteor showers. The best of all occurs around the middle of September every year, so be sure to watch. Perhaps it is the Japanese dragon “Ryu” and he will grant your wish!”
Images that accompany this article are: Historical Draco Figure from Uranometria, Draco Map Created by Torsten Bronger, Dragon Eggs Screensaver, and Animation by Michelet B. We thank you!
STS-125 crew members aboard Atlantis (pictured above) will hang out at least a day longer in space, following foul weather that prevented a timely landing today at NASA’s Kennedy Space Center in Florida.
And the forecast isn’t looking any sunnier for at least a little while.
There’s a 70 percent likelihood that storms will stick around today, with that chance dropping slightly to 60 percent through Saturday. By early next week, the chance of thunderstorms will have dropped below 50 percent.
NASA Flight Director Norm Knight and the entry team will evaluate weather conditions at Kennedy before permitting Atlantis and its crew to land at 9:16 a.m. Saturday. A second Kennedy landing opportunity is at 10:54 a.m. The shuttle also has landing opportunities at Edwards Air Force Base in California at 10:46 a.m. and 12:24 p.m.
If Atlantis does not land Saturday, there are multiple landing opportunities Sunday at Kennedy, Edwards, or White Sands Space Harbor in New Mexico.
Meanwhile, here are some ways to keep current on the mission’s finale:
Greetings, fellow SkyWatchers! Are you ready for a dark sky observing weekend? Then let’s take a ride with Wild’s Triplets, join Markarian’s Chain gang and hang out with the night Owls. Are you ready? Then grab your telescopes and binoculars and I’ll see you in the backyard….
Friday, May 22, 2009 – Let’s begin the day by honoring the 1920 birth on this date of Thomas Gold, an astronomer known for proposing the ‘‘steady-state’’ theory of the universe; for explaining pulsars; and for giving the magnetosphere its name. Gold was also an auditory research genius. In his interview with D.T. Kemp he stated:
‘‘I’m a compulsive thinker, I never turn my brain off, I’ve never in my life complained of being bored because I’m constantly thinking about some problem, mostly physics I suppose. A problem is always on my mind – evidently even in my sleep because I often wake up with a solution clearly spread out.’’
For the large telescope and seasoned observer, the challenge for this evening will be 5.5 degrees south of Beta Virginis, and one half degree west (RA 11 46 45 Dec -03 50 53). Classified as Arp 248, and more commonly known as ’’Wild’s Triplet,’’ these three very small interacting galaxies are a real treat! Best with around a 9-mm eyepiece, use wide aversion, and try to keep the star just north of the trio at the edge of the field to cut glare. Be sure to mark your Arp Galaxy challenge list!
Saturday, May 23, 2009 – Tonight let’s hop to far northern skies for a look at two gems. Start with Beta Ursae Majoris – the southwestern star of the Big Dipper – and begin scanning about a finger-width southeast for M108 (RA 11 11 31 Dec +55 40 31). At magnitude 10, you’ll appreciate this splendid edge-on galaxy! Discovered by Pierre Mechain on February 19, 1781, and later verified by Charles Messier, it didn’t formally enter the Messier’s catalog until 1953 at the hand Owen Gingerich. Despite its low surface brightness, M108 can be spotted by mid-aperture telescopes, and larger scopes will make out irregular patches of detail.
Now, hop on less than a finger-width further southeast (RA 11 14 47 Dec +55 01 08) where you’ll spot M97, the ‘‘Owl Nebula.’’ Discovered by Pierre Mechain 3 days earlier than M108, the Owl is often thought of as one of the most difficult of the Messier studies to detect from urban locations… and it may require a light pollution filter to help bring it to life. About the apparent size of Jupiter, the Owl gets its name from the vague gray-greenness of its light, and the two curious eye-like voids visible through larger scopes. Scientists believe the voids are the result of a line-of-sight phenomenon, where the lowest-density poles lie at an oblique angle from our vantage point. The structure of M97 and its fluorescence are associated with a high surface temperature central star in the last stages of life. Can you spot the faint 16th magnitude dying star at its heart?
Sunday, May 24, 2009 – Tonight is the New Moon and time to tour the galaxy fields of Virgo. For large telescopes, this is the ‘‘field of dreams’’… Start four finger-widths east-southeast of Beta Leonis for part of ‘‘ Markarian’s Chain ’’ and discover M84 and M86 (RA 12 25 03 Dec +12 53 13)! Good binoculars and small telescopes reveal the matched ellipticals of M84/86, while mid-sized telescopes will note that western M84 is slightly brighter and smaller. Larger scopes see these two galaxies literally ‘‘leap’’ out of the eyepiece at even modest magnifications!
In large telescopes, the bright galactic forms of M84/86 can be held with direct vision, while aversion welcomes many other mysterious strangers into view. Forming an easy triangle with the two Messiers, and located about 200 south, is 11th magnitude NGC4388, a classic edge-on spiral. Dim NGC4387 (magnitude 12) appears in the center of a triangle as a small face-on spiral with a noticeable dust lane. In large scopes, the central structure forms a curved ‘‘bar’’ of light, and the dust lane cleanly separates the central bulge of the core. East of M86 are two brighter NGC galaxies – 4435 and 4438.
In an average telescope, NGC 4435 has a simple star-like core and wispy round body structure, while NGC 4438 is a dim elliptical. The beauty of the pair is their proximity to each other! At times, a conspicuous wisp of galactic material can be seen stretching back toward the nearby (brighter) galaxy pair M84/86. Happy hunting!
Until next week? “Keep on rockin’ in the free world…”
This week’s awesome images are (in order of appearance): Thomas Gold (historical image), Arp 248: Wild’s Triplet (credit—Adam Block/NOAO/AURA/NSF), M108 and M97 (credit—Palomar Observatory, courtesy of Caltech) and Wide-field image of the Virgo galaxy cluster with M84/86 region to the upper right (credit—NOAO/AURA/NSF). We thank you so much!
A sizable collaboration of researchers has unveiled an enormous set of data from NASA’s Opportunity rover today — data that testify to the rover’s lucky longevity, and paint a picture of climate events that have shaped Victoria Crater, shown in this NASA/JPL-Caltech image.
The climate history is vast and compelling, including dramatic floods and terrain-shaping winds spanning billions of years. The data appear in today’s issue of the journal Science.
Because of the Mars rovers’ ability to move from place to place and also because of their unexpected long lives, the mission scientists have been able to study Mars in situ in a way they weren’t anticipating.
“There’s no way Spirit and Opportunity could have made all of these discoveries without the longevity that they’ve had,” said principal investigator Steve Squyres, of Cornell University in Ithaca, N.Y. “Mars has been good to us, but more than anything else, I think their longevity is testimony to the excellence of the work that was done by the team that built these vehicles so many years ago.” Pancam false-color image of the east face of Cape Verde, showing typcal impact-related stratigraphy. Credit: NASA/JP
The Opportunity rover has been able to study in detail three different craters located over three miles apart. Data and images from the rover show similar patterns in sedimentary rocks in each crater, patterns that could only have been laid down by ancient water flow. According to Squyres and his team, this discovery means that water once covered the entire area and helped shape that region of the planet long ago.
The rover revealed that water repeatedly came and left billions of years ago. Wind persisted much longer, heaping sand into dunes between ancient water episodes. These activities still shape the landscape today. At Victoria, steep cliffs and gentler alcoves alternate around the edge of a bowl about 0.8 kilometers (half a mile) in diameter. The scalloped edge and other features indicate the crater once was smaller than it is today, but wind erosion has widened it gradually. More layering in Victoria Crater. Credit: NASA/JPL
“What drew us to Victoria Crater is the thick cross-section of rock layers exposed there,” Squyres said. “The impact that excavated the crater millions of years ago provided a golden opportunity, and the durability of the rover enabled us to take advantage of it.”
Imaging the crater’s rim and interior, Opportunity inspected layers in the cliffs around the crater, including layered stacks more than 10 meters (30 feet) thick. Distinctive patterns indicate the rocks formed from shifting dunes that later hardened into sandstone, according to Squyres and 33 co-authors.
Instruments on the rover’s arm studied the composition and detailed texture of rocks just outside the crater and exposed layers in one alcove called “Duck Bay.” Rocks found beside the crater include pieces of a meteorite, which may have been part of the impacting space rock that made the crater.
Inside Duck Bay, the rover found that the lower layers showed less sulfur and iron, more aluminum and silicon. This composition matches patterns Opportunity found earlier at the smaller Endurance Crater, about 6 kilometers (4 miles) away from Victoria, indicating the processes that varied the environmental conditions recorded in the rocks were regional, not just local.
Squyres said there were specific minerals and specific patterns in the geochemistry of the crater walls. In all three craters, Eagle, Endurance and Victoria, the round, iron-rich spherules — BB-like structures — which the scientists nicknamed “blueberries,” were found embedded in the rock. The scientists have concluded that these were created from mineral deposits emerging from a watery solution inside the rock.
Opportunity gained more than 30 meters (98 feet) of elevation travelling from Endurance to Victoria, and the amount of “blueberries” decreased with the elevation. But once the rover entered Victoria crater, which is about 75 meters (246 feet) deep — and 750 meters in diameter — the spherules reappeared in the soil.
The spherules in rocks deeper in the crater are larger than those in overlying layers, suggesting the action of groundwater was more intense at greater depth.
Opportunity’s first observations showed interaction of volcanic rock with acidic water to produce sulfate salts. Dry sand rich in these salts blew into dunes. Under the influence of water, the dunes hardened to sandstone. Further alteration by water produced the iron-rich spherules, mineral changes and angular pores left when crystals dissolved away.
A rock from space blasted a hole about 600 meters (2,000 feet) wide and 125 meters (400 feet) deep. Wind erosion chewed at the edges of the hole and partially refilled it, increasing the diameter by about 25 percent and reducing the depth by about 40 percent.
Since leaving Victoria Crater about eight months ago, Opportunity has been on its way to study a crater named Endeavour that is about 20 times bigger than Victoria. The rover has driven about one-fifth of what could be a 16-kilometer (10-mile) trek to this new destination.
Sources: NASA and an e-mail exchange with Steve Squyres.
