Posted on by Fraser Cain

Volcanic Mountain

View north into the summit crater of Redoubt volcano where recent eruptions have removed a significant portion of the glacial ice. A remnant shelf of ice remains on the west (right) side of crater, and in this view, fumaroles are rising from near the ice/wall-rock contact. Image Creator: Payne, Allison

[/caption]
Feel the ground. It’s nice and cool, right? Well, dig down a few kilometers and things really heat up. Once you’re down more than 30 km, and temperatures can reach more than 1,000 degrees C; that’s hot enough to melt rock. The melted rock is called magma, and it collects into vast chambers beneath the Earth’s surface. The molten rock is less dense than the surrounding rock and so it “floats” upwards through cracks and faults. When the magma finds its way to the surface, it erupts as lava, rock, ash and volcanic gases; this is a volcanic mountain.

A volcanic mountain starts out as a simple crack in the Earth called a volcanic vent. Magma erupts out of the ground as lava flows, clouds of ash, and explosions of rock. This material falls back to Earth around the vent, and piles up around it. Over time (and sometimes quite quickly) a volcanic mountain builds up, with the familiar cone shape.

There are different kinds of volcanic mountains. Cinder cone mountains are made up of material blasted out that rains back down. They don’t usually grow too large. Shield volcanoes are built up by many lava flows of low viscosity lava (low viscosity means that it flows more easily). The lava can flow for dozens of kilometers, and the volcano can be very wide. A stratovolcano or composite volcano is made up of many layers of ash, rock and hardened lava. Some of the largest, most impressive volcanoes in the world are stratovolcanoes (think about Mount Fuji or Rainier).

And we don’t just have volcanic mountains here on Earth. The largest mountain in the Solar System is Olympus Mons on Mars. This enormous shield volcano has grown to more than 21 km tall. There are also active volcanoes on Jupiter’s moon Io.

We have written many articles about volcanoes for Universe Today. Here’s an article about the biggest volcano in the Solar System, and here’s an article about different types 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.

Posted on by Fraser Cain

Dome Mountains

Half dome mountain. Credit: Mila Zinkova

[/caption]
The interior of the Earth is hot enough to melt rock, and that’s just what happens. Melted rock squeezes together into vast pools of magma beneath the ground. Since it’s less dense than the surrounding rock, it makes its way upward to the surface. If the magma reaches the surface you get a volcano; with the ash, and the lava and the explosions. But if the magma pushes up but doesn’t actually crack through the surface, you can get a dome mountain.

Dome mountains don’t usually get as high as folded mountains because the force of the magma underneath doesn’t push hard enough. Over a long period, the magma cools to become cold, hard rock. The result is a dome-shaped mountain.

Over long periods of time, erosion wipes away the outer layers of the mountain, exposing the dome-shaped cooled magma of harder rock.

An example of a dome-shaped mountain is Half Dome in the Sierra Nevada range in California. It’s made of granite, and was once a large blob of magma pushed up through the Earth. Granite is much harder than other rock, and so it doesn’t erode as easily as the rest of the mountain. The softer layers of sedimentary rock were washed away, leaving the hard granite dome.

Other dome mountains aren’t so easy to spot. You need satellite images to see the circular shape in the Earth’s surface.

We have written many articles about the Earth for Universe Today. Here’s an article about how satellites can measure the movement of the Earth after an earthquake.

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.

Posted on by Fraser Cain

Fault-Block Mountains

Diagram of a fault-block mountain range.

[/caption]
Fault-block mountains are formed by the movement of large crustal blocks when forces in the Earth’s crust pull it apart. Some parts of the Earth are pushed upward and others collapse down.

To understand a fault-block mountain, or sometimes referred as a “fault mountain”, you need to understand what a fault is. Faults are simply cracks in the Earth’s crust. The surface of the Earth can move along these faults, and displace rock layers on either side. Wherever you have movement along the faults, you can get earthquakes, and over long periods of time mountains form under the intense pressure.

Large blocks of rock along the sides of these faults can be uplifted and tilted sideways by this incredible force. And then, on the opposite sides of the faults, the ground tilts downwards forming a depression. This depression gets filled in and leveled by the erosion of the mountains above.

The Sierra Nevada mountains in California are an example of a fault-block mountain range.

We have written many articles about the Earth for Universe Today. Here’s an article that shows how satellites can calculate the movement of the Earth during earthquakes.

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.

Posted on by Nancy Atkinson

New Finding Shows Super-Huge Space Tornados Power the Auroras

Space tornadoes span a volume approximately the size of Earth or larger. Credit: Keiling, Glassmeier and Amm

[/caption]
If you think tornadoes on Earth are scary, newly found “space tornadoes” sound downright horrifying. But they are likely the power source behind the beautiful Northern and Southern Lights. A new finding by a cluster of five space probes – the THEMIS, or Time History of Events and Macroscale Interactions during Substorms show that electrical funnels which span a volume as large as Earth produce electrical currents exceeding 100,000 amperes. THEMIS recorded the extent and power of these electrical funnels as the probes passed through them during their orbit of Earth. Ground measurements showed that the space tornadoes channel the electrical current into the ionosphere to spark bright and colorful auroras on Earth.

Space tornadoes are rotating plasmas of hot, ionized gas flowing at speeds of more than a million miles per hour, far faster than the 200 m.p.h. winds of terrestrial tornadoes, according to Andreas Keiling, a research space physicist at the University of California, Berkeley’s Space Sciences Laboratory.

Keiling works on THEMIS, which was built and is now operated by UC Berkeley. The five space probes were launched by NASA in February 2007 to solve a decades-long mystery about the origin of magnetic storms that power the Northern and Southern Lights.

Electric currents in the funnels power auroras. Credit: Keiling, Glassmeier, and Amm
Electric currents in the funnels power auroras. Credit: Keiling, Glassmeier, and Amm

Both terrestrial and space tornadoes consist of funnel-shaped structures. Space tornadoes, however, generate huge amounts of electrical currents inside the funnel. These currents flow along twisted magnetic field lines from space into the ionosphere where they power several processes, most notably bright auroras such as the Northern Lights, Keiling said.

While these intense currents do not cause any direct harm to humans, on the ground they can damage man-made structures, such as power transformers.

The THEMIS spacecraft observed these tornadoes, or “flow vortices,” at a distance of about 40,000 miles from Earth. Simultaneous measurements by THEMIS ground observatories confirmed the tornadoes’ connection to the ionosphere.

Keiling’s colleagues include Karl-Heinz Glassmeier of the Institute for Geophysics and Extraterrestrial Physics (IGEP, TU) in Braunschweig, Germany, and Olaf Amm of the Finnish Meteorological Institute.

The findings were presented today at the general assembly of the European Geosciences Union (EGU) in Vienna, Austria.

Source: EGU

Posted on by Nancy Atkinson

New Hubble Survey Supports Cold Dark Matter in Early Universe

NICMOS Image of the GOODS North field. Credit: C Conselice, A Bluck, GOODS NICMOS Team.

[/caption]

A new survey is revealing how the most massive galaxies formed in the early Universe, and the findings support the theory that Cold Dark Matter played a role. A team of scientists from six countries used the NICMOS near infrared camera on the Hubble Space Telescope to carry out the deepest ever survey of its type at near infrared wavelengths. Early results show that the most massive galaxies, which have masses roughly 10 times larger than the Milky Way, were involved in significant levels of galaxy mergers and interactions when the Universe was just 2-3 billion years old.

“As almost all of these massive galaxies are invisible in the optical wavelengths, this is the first time that most of them have been observed,” said Dr. Chris Conselice, who is the Principal Investigator for the survey. “To assess the level of interaction and mergers between the massive galaxies, we searched for galaxies in pairs, close enough to each other to merge within a given time-scale. While the galaxies are very massive and at first sight may appear fully formed, the results show that they have experienced an average of two significant merging events during their life-times.”

The results show that these galaxies did not form in a simple collapse in the early universe, but that their formation is more gradual over the course of the Universe’s evolution, taking about 5 billion years.

NICMOS image of merging galaxies. Credit: C Conselice, A Bluck, GOODS NICMOS Team
NICMOS image of merging galaxies. Credit: C Conselice, A Bluck, GOODS NICMOS Team

“The findings support a basic prediction of the dominant model of the Universe, known as Cold Dark Matter,” said Conselice, “so they reveal not only how the most massive galaxies are forming, but also that the model that’s been developed to describe the Universe, based on the distribution of galaxies that we’ve observed overall, applies in its basic form to galaxy formation.”

The Cold Dark Matter theory is a refinement of the Big Bang theory, which includes the assumption that most of the matter in the Universe consists of material that cannot be observed by its electromagnetic radiation and hence is dark matter, while at the same time the particles making up this matter are slow and are thereforer cold.

The preliminary results are based on a paper led by PhD student Asa Bluck at the University of Nottingham, and were presented this week at the European Week of Astronomy and Space Science at the University of Hertfordshire.

The observations are part of the Great Observatories Origins Deep Survey (GOODS), a campaign that is using NASA’s Spitzer, Hubble and Chandra space telescopes together with ESA’s XMM Newton X-ray observatory to study the most distant Universe.

Source: RAS

Posted on by Fraser Cain

Fold Mountains

Mount Everest from Kalapatthar. Photo: Pavel Novak

[/caption]
Some of the most dramatic mountains in the world are fold mountains. These are created when two of the Earth’s tectonic plates crash together – like in a head-on car crash. The edges of the two plates buckle and fold, and the peaks of these folds are mountains. Entire mountain ranges, thousands of kilometers long, are created during these slow motion collisions between tectonic plates.

Some famous examples of fold mountains are the Himalayan mountains in Asia and the Rocky Mountains in North America. Consider the fact that the Earth’s tectonic plates are moving very slowly, just a few centimeters every year. These folding collisions play out in incredibly slow motion, taking millions of years. The Indian subcontinent crashed into Asia 24 million years ago, and since then it has built up the Himalayan mountains – the tallest mountains in the world. In fact, the Himalayans are still growing.

Want to make your own folded mountain range? Take two flat strips of modeling clay and put them side to side. Then slowly push one strip into the other and you’ll see how one or both will crumple up under the pressure. You’ll make your own mini mountain range.

We have written many articles about mountains for Universe Today. Here’s an article about different types of mountains.

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.

Posted on by Fraser Cain

Types of Mountains

Mount Everest from Kalapatthar. Photo: Pavel Novak

[/caption]
One feature of the Earth that you can’t miss are its mountains. But did you know there are different types of mountains? The different mountain types are formed in different ways, through tectonic plates crunching into each other, or sliding past one another, or even from magma coming up out of the Earth. The mountains are different in their appearance, and in their formation. Let’s take a look at each of the major mountain types.

Fold Mountains
The most common type of mountain in the world are called fold mountains. When you see vast mountain ranges stretching on for thousands of kilometers, those are fold mountains. Fold mountains are formed when two of the Earth’s tectonic plates collide head on; like two cars crashing together. The edges of each tectonic plate crumple and buckle, and these create the mountains. Some examples of fold mountain ranges include the Rocky Mountains in North America, and the Himalayan Mountains in Asia.

Fault-Block Mountains
Fault-block mountains (or just “block mountain“) are created when faults or cracks in the Earth’s crust force materials upward. So instead of folding, like the plate collision we get with fold mountains, block mountains break up into chunks and move up or down. Fault-block mountains usually have a steep front side and then a sloping back side. Examples of fault-block mountains include the Sierra Nevada mountains.

Dome Mountains
Dome mountains are created when a large amount of magma pushes up from below the Earth’s crust, but it never actually reaches the surface and erupts. And then, before it can erupt, the source of the magma goes away and the pushed up rock cools and hardens into a dome shape. Since the dome is higher than its surroundings, erosion works from the top creating a circular mountain range.

Volcanic Mountains
Here’s a fairly familiar kind of mountain. Volcanic mountains are created when magma from beneath the Earth makes its way to the surface. When does get the surface, the magma erupts as lava, ash, rock and volcanic gases. This material builds up around the volcanic vent, building up a mountain. Some of the largest mountains in the world were created this way, including Mauna Loa and Mauna Kea on the Big Island of Hawaii. Other familiar volcanoes are Mt. Fuji in Japan and Mt. Rainier in the US.

Plateau Mountains
Plateau mountains are actually formed by the Earth’s internal activity; instead, they’re revealed by erosion. They’re created when running water carves deep channels into a region, creating mountains. Over billions of years, the rivers can cut deep into a plateau and make tall mountains. Plateau mountains are usually found near folded mountains.

We have written many articles about mountains for Universe Today. Here’s an article about a massive mountain range seen on Titan, and the search for a mountain of eternal sunlight on the Moon.

Here are more article about mountains:

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:
http://en.wikipedia.org/wiki/List_of_mountain_types
http://www.wvgs.wvnet.edu/www/geology/geolf001.htm
http://library.thinkquest.org/05aug/00184/Mountain%20Ranges%20Page.htm

Posted on by Nancy Atkinson

New Image of Jet-Driven Galactic Shock Wave is a Shocker

The image shows in red the X-ray emission produced by high-energy particles accelerated at the shock front where Centaurus A's expanding radio lobe (shown in blue) collides with the surrounding galaxy. (In the top-left corner X-ray emission from close to the central black hole, and from the X-ray jet extending in the opposite direction can also be seen.) Credit: NASA

[/caption]
The Chandra X-ray observatory has taken a closer look at the galaxy Centaurus A, and new images have revealed in detail the effects of a shock wave blasting through the galaxy. Powerful jets of plasma emanating from a supermassive black hole at the galactic core are creating the shock wave, and the new observation, have enabled astronomers to revise dramatically their picture of how jets affect the galaxies in which they live.

A team led by Dr. Judith Croston from the University of Hertfordshire and Dr. Ralph Kraft, of the Harvard-Smithsonian Center for Astrophysics used very deep X-ray observations from Chandra to get a new view of the jets in Centaurus A. The jets inflate large bubbles filled with energetic particles, driving a shock wave through the stars and gas of the surrounding galaxy. By analyzing in detail the X-ray emission produced where the supersonically expanding bubble collides with the surrounding galaxy, the team were able to show for the first time that particles are being accelerated to very high energies at the shock front, causing them to produce intense X-ray and gamma-ray radiation. Very high-energy gamma-ray radiation was recently detected from Centaurus A for the first time by another team of researchers using the High Energy Stereoscopic System (HESS) telescope in Namibia.

“Although we expect that galaxies with these shock waves are common in the Universe, Centaurus A is the only one close enough to study in such detail,” said Croston. “By understanding the impact that the jet has on the galaxy, its gas and stars, we can hope to understand how important the shock waves are for the life cycles of other, more distant galaxies.”

Centaurus A (NGC 5128) is one of our closest galactic neighbors, and is located in the southern constellation of Centaurus. The supermassive black hole is the source of strong radio and X-ray emissions. Visible in the image below, (click here for a zoomable image from Chandra) a combined image from Chandra and the Atacama Pathfinder Experiment (APEX) telescope in Chile, is a dust ring encircling the giant galaxy, and the fast-moving radio jets ejected from the galaxy center.

Centaurus A. Credit: ESO/WFI (Optical); MPIfR/ESO/APEX/A.Weiss et al. (Submillimetre); NASA/CXC/CfA/R.Kraft et al. (X-ray)
Centaurus A. Credit: ESO/WFI (Optical); MPIfR/ESO/APEX/A.Weiss et al. (Submillimetre); NASA/CXC/CfA/R.Kraft et al. (X-ray)

The powerful jets are found in only a small fraction of galaxies but are most common in the largest galaxies, which are thought to have the biggest black holes. The jets are believed to be produced near to a central supermassive black hole, and travel close to the speed of light for distances of up to hundreds of thousands of light years. Recent progress in understanding how galaxies evolve suggests that these jet-driven bubbles, called radio lobes, may play an important part in the life cycle of the largest galaxies in the Universe.

Energetic particles from radio galaxies may also reach us directly as cosmic rays hitting the Earth’s atmosphere. Centaurus A is thought to produce many of the highest energy cosmic rays that arrive at the Earth. The team believes that their results are important for understanding how such high-energy particles are produced in galaxies as well as for understanding how massive galaxies evolve.

The results of this research will be published in a forthcoming issue of the Monthly Notices of the Royal Astronomical Society and were presented at the European Week of Astronomy and Space Science in the UK.

Source: RAS

Posted on by Ian O'Neill

Could Orion be Downgraded from a Six to Four Astronaut Vehicle?

A cut away graphic of the Orion Crew Module... with six seats (NASA)

[/caption]

To save on weight, NASA engineers are considering the option to remove two seats from the Orion crew exploration vehicle. According to the manager of the Constellation Program, a possible redesign option has been discussed with the International Space Station (ISS) partners despite the fact that the initial operational capability (IOC) to deliver crew to the ISS calls for a six-seat version. Although the space station crew will have expanded to six by the end of next month, NASA is confident the loss of two seats on Orion won’t cause any operational problems… at least we’ll still have Soyuz.

Today, the Orlando Sentinel reported that the Constellation Program, due to budget problems, probably won’t be ready for a return trip to the Moon until 2020, two years later than officially planned (NASA hoped for a 2018 mission). Now NASA engineers are concerned that the lunar mission may slip even further behind schedule.

To compound this bad news, NASA is weighing up its options to free up some mass from the initial Orion launches atop the Ares I rocket. This issue arose after Jeff Hanley, manager of the Constellation Program and Orion developer, said the Orion design was within “plus or minus a couple of hundred pounds” of the 21,000-pound maximum for the command module set by a safety requirement to land with only two of the three main parachutes deployed should one fail after reentry.

“Right now we’re studying and really on the verge of deciding that we’re going to start with four,” Hanley said. “That gives us a common lunar and ISS version, but we’ve sized the system and have a design for six, so we’ll grow our capability as we need it.” So it’s not all bad news, the first launches may consist of four astronauts, but Orion could be modified to cater for six.

Hanley is keen to point out that although the brand new NASA manned space vehicle may be operating at a reduced capacity, at least Roscosmos will be able to help out. “Our Russian partners are always going to fly Soyuz or something derivative to that, so we’ll have the full coverage of being able to get the crew off the station in a pinch on the Soyuz and in the Orion,” he added. Soyuz is a three-crew space vehicle and is currently used by the space station as a “lifeboat” should an emergency crop up in orbit.

Apparently the Orion weight problem has been around for a while as the design of Orion is based on predicted weights, and not actual launch weight; if the actual weight exceeds that of the safety margin, cutbacks would be required. In this case the cutback may include two crew members.

Hanley points out that although the early Constellation flights may include a four-crew IOC, it would stand NASA in good stead so a good understanding of how well it performs with four seats before the possibility of expanding it to six.

Source: Aviation Week

Posted on by Ian O'Neill

Young Asteroids Age Fast with a Solar Wind Tan

Young asteroid tanning is big business in the Solar System (ESO)

[/caption]

If you stay out in the Sun too long, you’ll eventually get a suntan (or sunburn); your skin will also get damaged and it will show signs of ageing faster. This might sound like a sunblock ad, but the same principal holds true for the small chunks of rock floating around in the Solar System. Yes, a young asteroid’s surface will age prematurely, but it’s not caused by the Sun’s ultraviolet rays, it’s caused by the solar wind…

Within a million years, an asteroid can turn from lunar grey to Martian red when left out in the solar wind. A million years is a tiny amount of time in relation to the Solar System’s lifetime. Why is this important? European Southern Observatory (ESO) researchers have realized that this finding will not only help astronomers relate an asteroid’s appearance with its history, but it can act as an indicator for after effects of impacts with other asteroids.

It turns out that the study of “space weathering” is fairly controversial, scientists have been mulling it over for a long time. Central to the problem is the fact that the appearance of the interior of meteorites found on Earth are remarkably different to the asteroids we see in space; asteroids are redder than their meteorite cousins. So what causes this redness?

“Asteroids seem to get a ‘sun tan’ very quickly,” says lead author Pierre Vernazza. “But not, as for people, from an overdose of the Sun’s ultraviolet radiation, but from the effects of its powerful wind.”

Although this is an interesting discovery, the speed at which the “tanning” occurs is astonishing. After an asteroid collision, fresh asteroid chunks are created with new surfaces. Within a million years these young asteroid surfaces will turn a dirty shade of red as the surface minerals are continuously battered by ionizing solar wind particles. “The charged, fast moving particles in the solar wind damage the asteroid’s surface at an amazing rate,” Vernazza added.

Naturally, a lot depends on the mineral composition of an asteroid’s surface, influencing how red its surface will become, but most of the tanning effect occurs in the first million years. Afterwards, the tanning continues, just at a slower rate.

Asteroid observations also reveal that the high proportion of “fresh surfaces” seen on near-Earth asteroid probably isn’t down to asteroid collisions. The frequency of collisions is far lower than the sun-tanning timescales, meaning that there shouldn’t be any “fresh surfaces” to be seen. It is far more likely that the upper layers of asteroids are renewed through planetary encounters, where the gravitational field of planets “shake off” the tanned dust.

Source: ESO