An ash cloud looms in the distance near Kachemak Bay Bluffs. Credit: Steve Baird, AVO
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Alaska’s Mount Redoubt erupted twice Thursday morning, creating a 12-mile-high cloud of ash. The Alaska Volcano Observatory reported the first eruption came about 8:30 a.m., sending an ash cloud more than 9,100 meters (30,000) feet in the air. A second eruption came about an hour later, and blasted ash 20,000 meters (65,000 feet) high. After the second eruption, mud flows called lahars near the base of the volcano ran into the nearby Drift River. The National Weather Service also issued a flash flood warning for regions surrounding the Drift River, as eruptions can cause snow and ice to melt, causing the river to swell with melt water. The ash is predicted to drift as far as Anchorage, which lies about 160 km (100 miles) northeast of the volcano.
Redoubt ash plume. NASA images created by Jesse Allen, using data provided courtesy of the MODIS Rapid Response team
The volcano erupted with five smaller blasts on Monday, but had been relatively quiet for the past two days. Since the earlier eruptions occurred during the night, satellite images were not available during the peak times of eruptions, but scientists are hoping satellites were able to capture the latest eruptions in action.
Airlines have canceled flights around the area, as ash poses a significant threat to aircraft engines. Some regions surrounding Mount Redoubt have been evacuated.
Geologists with the U.S. Geological Survey have said a lot of snow and ice remains on the mountain, increasing the danger from mud flows that already have downed hundreds of trees and carved a huge gouge out of a glacier.
If you didn’t get a chance to watch the IYA telescope “live” on Galactic TV today, don’t worry. We took a video capture for you. Step inside to enjoy today’s view of Alpha Centauri…
Alpha Centauri (alpha Centauri / alpha Cen); (also known as Rigil Kentaurus, Rigil Kent, or Toliman) is the brightest star in the southern constellation of Centaurus and an established binary star system, Alpha Centauri AB (alpha Cen AB). To the unaided eye it appears as a single star, whose total visual magnitude identifies it as the third brightest star in the night sky. Alpha Centauri is the closest star system to the Solar System, being only 1.34 parsecs, or 4.37 light years away from our Sun.
Popularly known, Alpha Centauri is the closest star system to our Solar System. It lies about 4.37 light-years in distance, or about 41.5 trillion kilometres, 25.8 trillion miles or 277,600 AU. Astronomer Thomas James Henderson made the original discovery from many exacting observations of the trigonometric parallaxes of the AB system between April 1832 and May 1833. He withheld the results because he suspected they were too large to be true, but eventually published in 1839 after Friedrich Wilhelm Bessel released his own accurately determined parallax for 61 Cygni in 1838. For this reason, we consider Alpha Centauri as the second star to have its distance measured.
Alpha Centauri A is the principal member or primary of the binary system, being slightly larger and more luminous than our Sun. It is a solar-like main sequence star with a similar yellowish-white colour, whose stellar classification is spectral type G2 V.[12] From the determined mutual orbital parameters, Alpha Cen A is about 10% more massive than our Sun, with a radius about 23% larger.
Alpha Centauri B is the companion star or secondary, slightly smaller and less luminous than our Sun. This main sequence star is of spectral type of K1 V, making it more an orangish-yellow color than the whiter primary star. Alpha Cen B is about 90% the mass of the Sun and 14% smaller in radius. Although it has a lower luminosity than component A, star B’s spectrum emits higher energies in X-rays. The light curve of B varies on a short time scale and there has been at least one observed flare.
Together, the bright visible components of the binary star system are called Alpha Centauri AB (Alpha Cen AB). This “AB” designation denotes the apparent gravitational centre of the main binary system relative to other companion star(s) in any multiple star system.[15] “AB-C” refers to the orbit of Proxima around the central binary, being the distance between the centre of gravity and the outlying companion. Some older references use the confusing and now discontinued designation of A×B. Since the distance between the Sun and ? Cen AB does not differ significantly from either star, gravitationally this binary system is considered as if it were one object.
Alpha Centauri C, also known as Proxima Centauri, is of spectral class M5Ve or M5VIe, suggesting this is either a small main sequence star (Type V) or sub-dwarf (VI) with emission lines, whose B-V colour index is +1.81. Its mass is about 0.12 M. R.T.A. Innes from South Africa in 1915 discovered Proxima Centauri by blinking photographic plates taken at different times during a dedicated proper motion survey. This showed the large proper motion and parallax of the star was similar in both size and direction to those of ? Centauri AB, suggesting immediately it was part of the system and slightly closer to us than ? Centauri AB. Lying 4.22 light-years away, Proxima Centauri is the nearest star to the Sun. All current derived distances for the three stars are presently from the parallaxes obtained from the Hipparcos star catalog (HIP).
As always, you can visit the remote telescope by clicking on the IYA “LIVE Remote Cam” Logo to your right. We’ll be broadcasting whenever skies are clear and dark in Central Victoria! Enjoy….
New high-resolution images taken last month of Mars’ south polar region are revealing signs of spring that are decidedly Martian.
The image above features a spider trough network left behind as seasonal dry ice caps have sublimated away in the warmer temperatures. It’s part of a new series of images released this week by the University of Arizona’s High Resolution Imaging Experiment, or HiRISE, aboard NASA’s Mars Reconnaissance Orbiter.
See more information and photos below.
The gas beneath the ice cap can flow in the same places year after year, eroding troughs in the surface of the planet.
“What happens on Mars, we think, is that as the seasonal ice cap thins from the bottom, gas underneath the cap builds up pressure,” said HiRISE deputy principal investigator Candice J. Hansen-Koharcheck of the NASA Jet Propulsion Laboratory in Pasadena, California.
“And where gas under the ice finds a weak spot or a crack, it will flow out of the opening, often carrying a little dust from the surface below.”
The next HiRISE image shows how dust that has been carried to the surface by gas jetting through the ice cap is blown about by prevailing winds before settling in fan-shaped deposits atop the ice cap. Varying orientations suggest that as the ice layer thins, a set of gas jets becomes active, they die down, then further away another set starts up at a later time with a different prevailing wind direction.
NASA/JPL/University of Arizona
Many jets appear to be active at the same time since numerous fans are all deposited in the same direction: this next, closer image is an example of such an occurrence.
Credit: NASA/JPL/University of Arizona
This southern hemisphere crater has gullies on its north and northeast walls. Gullies are proposed to be carved by liquid water originating from the subsurface or melting ice/snow on the surface.
Credit: NASA/JPL/University of Arizona
Dark dunes are visible on the crater floor. Lighter, smaller dunes rim the south side of the crater floor. The entire scene, pictured below, has a pitted texture, suggesting that ground ice was once present in this region. When ground ice sublimates (goes from a solid directly to a gas), it leaves behind empty spaces in the soil that turn into pits as the remaining overlying soil collapses to fill them.
Credit: NASA/JPL/University of Arizona
The full set of new HiRISE Mars images is here. Check out all the downloadable formats and sizes, with some even designed to fit an iPhone screen!
Mars image from the VMC, enhanced by submitted by Ian Musgrave, Adelaide, Australia. Credit: ESA
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The Mars Webcam is back in action after taking a three month hiatus surrounding Mars solar conjunction. If you don’t remember, or if haven’t heard about this “eye on Mars” before, here is a little background: the Visual Monitoring Camera (VMC) is part of the Mars Express spacecraft, ESA’s Mars orbiter. Its original purpose was to provide simple, low-tech images of Beagle lander separation. After the Beagle departed from the orbiter in Dec. 2003 (and subsequently wasn’t heard from again) the VMC was switched off. But in August of 2008 mission planners had the idea of trying to turn the camera back on, and using it as a “webcam,” which ran until December and solar conjunction. The VMC team also has a new blog and they are also looking for the public’s help in processing and cleaning up their images.
The Mars Webcam is not a scientific instrument, but it does provide fantastic views of Mars – including crescent views of the planet not obtainable from Earth.
According to the VMC blog, the scientific team is looking for the public’s help to interpret and rework images, as well as perform a little photo artistry (i.e. Photoshopping) on the images taken by this camera. “We cordially invite you to download any of our images sets and send us your results. We’ll post the best in our public gallery.”
Find more info on how to work with the VMC team here.
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It’s a busy day in space, with 13 humans now in orbit. A Soyuz rocket blasted off amid clouds and drizzle at the Baikonur Cosmodrome today (Thursday) sending Russian cosmonaut Gennady Padalka , American astronaut Michael Barratt,and American spaceflight participant Charles Simonyi on their way to the International Space Station. With lift-off at 11:49 a.m. GMT, Simonyi made history by becoming the first private explorer to make a second trip to the ISS. He previously flew to there in April 2007. With the shuttle Discovery crew of seven just leaving the station on Wednesday, the current ISS crew of three on board the station, and the Soyuz three, that totals equals the current record of 13 humans in space at one time*.
And things will just get busier: this new ISS crew will grow to six in May.
The Soyuz is scheduled to dock with the station at 01:14 p.m. GMT aturday, March 28. Padalka will serve as commander of Expeditions 19 and 20 aboard the station. Barratt will serve as a flight engineer for those two missions. Padalka and Barratt’s other crewmate is Koichi Wakata of the Japan Aerospace Exploration Agency. He arrived to the station March 17 on space shuttle Discovery.
Simonyi, flying to the station under a commercial agreement with the Russian Federal Space Agency, will spend 10 days aboard the ISS, and return to Earth April 7 with Expedition 18 Commander Michael Fincke and Flight Engineer Yury Lonchakov, who have been on the station since October 2008.
The Expedition 19 crew will continue science investigations and prepare for the arrival of the rest of the station’s first six-person contingent. Roman Romanenko of the Russian Federal Space Agency, Frank De Winne of the European Space Agency and Canadian Space Agency astronaut Bob Thirsk will launch from Baikonur on May 27, arriving at the station on May 29. After all the astronauts are aboard, Expedition 20 will begin, ushering in an era of six-person station crews. This mission also will be the first time the crew members represent all five International Space Station partners.
*A quick search of the times there were 13 people in space previously yielded it occurred in 1995 when STS-67 was in orbit, along with the crew of three on the Mir space station and a Soyuz in flight, and also in 1997 when STS-82 was doing a Hubble repair mission, and the Mir crew and a Soyuz crew were also in space. I’ll update that if I find out more, and if anyone else has more information, post a comment. Thanks!
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As you probably know, lava is the molten rock that comes out of volcanoes during eruptions. But what is it? What is lava, and how does it get so hot?
You’re standing on the Earth’s crust right now. But beneath your feet, the interior of the Earth gets must hotter. About 30 km beneath the Earth’s crust is the mantle; a vast region of hot rock that can be thousands of degrees. Although the mantle is mostly solid, it can form pockets of liquid rock called magma. This lava is much less dense than the surrounding rock, and so it “floats” up to the surface of the Earth through cracks and weaknesses in the Earth’s crust.
When it finally reaches the Earth’s surface and escapes, geologists call this hot rock magma. It’s still the same stuff, it’s just at the surface of the Earth now. Different kinds of lava will flow at different speeds when they erupt from a volcano. The least thick can flow in great rivers of molten rock for many kilometers. The thicker lava doesn’t flow very far at all, piling up around the volcanic vent, and creating the familiar cone shaped volcano. The thickest stuff doesn’t really flow at all, it just plugs up the volcano’s plumbing, and can lead to powerful explosions.
Lava can range in temperature from about 750 degrees C to more than 1100 C. The temperature of the lava actually depends on the composition of the minerals in it. Some contain large amounts of aluminum, potassium and calcium, while others have iron and magnesium.
There are several different types of volcanoes: steep stratovolcanoes, wide shield volcanoes, and mounded lava domes. The shape of a volcano actually depends on the types of lava that it’s made up of. And so, there are several different types of lava.
The type of lava coming out of a volcano depends on its mineral content. Some lava is very thin, and can flow out of a volcano in great rivers that go for dozens of kilometers. Other lava is very thick, and only flows for a short distance before cooling and hardening. And some lava is so thick that it barely “flows” at all, and can plug up the plumbing of a volcano.
The main types of lava have been given Hawaiian names, because of the volcanic nature of the Hawaiian islands. You can find examples of different kinds of lava flows on the island.
A’a
Pronounced “ah-ah”, this is a basaltic lava that doesn’t flow very quickly. It looks like a slowly moving mass of hot jello, with cooler, rough surface. Once it hardens, the sharp spiny surface of a’a lava is extremely difficult to walk across. These types of lava erupt at temperatures above 1000 to 1100 degrees C.
Pahoehoe
Pronounced “pa-ho-ho”, this type of lava is much thinner and less viscous than a’a. It can flow down the slopes of a volcano in vast rivers. The surface of the lava congeals into a thin crust that looks very smooth. Pahoehoe lava can also form lava tubes, where the rock hardens around a fast-moving liquid core. When that core flows out of the tube, a long tunnel remains. Pahoehoe erupts at temperatures of 1100 to 1200 C.
Pillow Lava
Pillow lava is typically found erupting from underwater volcano vents. As soon as the lava contacts the water, it’s cooled down and forms a hardened shell. As more lava issues from the vent, the shell of lava cracks and more “pillows” come out of these cracks.
We have written many articles about volcanoes for Universe Today. Here’s an article about the temperature of lava.
ISS at full length, taken from Discovery. Credit: NASA
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Space shuttle Discovery undocked from the ISS on Wednesday, providing the dramatic first views of the space station with its full company of solar arrays unfurled. “Discovery, Alpha, Godspeed,” ISS commander Mike Fincke radioed after the shuttle departed. “Thanks for making us symmetrical, giving us full power, and all the other wonderful things you did for us. You did great work. Come again.”
“Thanks for the great work as well,” shuttle commander Lee Archambault replied. “Have a good one, we’ll see you on the ground in about a month.”
The fly-around was timed to begin at orbital sunrise, to allow for good lighting for the much anticipated pictures. But everyone had to wait until later for a high-definition video replay on NASA TV. The shuttle’s KU-band television antenna didn’t have a good link with NASA’s relay satellites until after the fly-around was complete. The image above has been updated to show an official NASA image taken by the Discovery astronauts during the flyaround, and below are a few screenshots from the high-def replay, showing different views of the ISS, post undocking.
UPDATE: Video of the flyaround is now available, and can be seen below:
Screenshot of ISS flyaround by shuttle Discovery. Credit: NASA TV
ISS. Credit: NASA TV
At a mission briefing after the undocking, mission managers expressed their excitement at seeing the images of the space station at full length, saying they felt an extreme amount of pride and joy for everyone involved with the ISS project.
“We’re getting ready to turn the station over to the research community,” said Dan Hartman, chairman of the space station mission management team, “and they will be challenged to keep the crew busy — and that’s a good thing. By the end of May (when the ISS crew size will increase to six), we’ll be ready to go.”
The Discovery crew took Sandy Magnus along with them, bringing her her home after her long-duration stay on the ISS, and left behind Koichi Wakata, Japan’s first long-duration astronaut.
The shuttle is scheduled to land on Saturday, March 28 with the first landing opportunity at 1:43 pm EDT.
The temperature of lava when it is first ejected from a volcanic vent can vary between 700 and 1,200 degrees C (1,300 to 2,200 F).
As you probably know, lava is molten rock that comes out of a volcano during an eruption. Although the Earth’s mantle is solid, it’s so hot that puddles of molten rock can form between the mantle and the Earth’s crust. This lava is less dense than the surrounding rocks, and so it makes its way to the surface through cracks and faults in the Earth’s crust. Eventually, it erupts to the surface.
Even though lava is much thicker than water, it can flow great distances across the surface of the Earth before it cools and hardens. Some lava is very thin, and can flow many kilometers, while other lava is thick and doesn’t flow at all; it just piles up around the volcanic vent.
Whether lava is thick or thin doesn’t depend on the temperature of the lava. Instead it’s caused by the minerals in the lava. The coolest lava are felsic lavas, which can erupt at temperatures as low as 650-750 C. Next are the andesitic lavas, which erupt in the range of 750-950 C. Basaltic lavas typically erupt at temperatures above 950 C.
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Stratovolcanoes, or composite volcanoes, are some of the largest, most familiar mountains on Earth. Perhaps you’ve heard of Mount Fuji, Mount Kilimanjaro, or Mount Rainier? These are stratovolcanoes. They’ve got that familiar shape with the gently sloping lower sides and then the sharp cone shape at the top. They make up 60% of the Earth’s individual volcanoes.
They typically have a layered or stratified appearance, with alternating lava flows, mudflows, fallen ash, and other debris. They usually form along the margins of the Earth’s tectonic plates, where one plate is pushing beneath another, or they’re sliding together. This creates weaknesses in the Earth’s crust, where magma from beneath the surface can escape.
Stratovolcanoes will usually have a central caldera, or crater, at the top, but they will also have a network of vents. They can have many lava domes and smaller vents where eruptions can occur; not just from the top. The lava flows out of them is extremely thick, and sometimes it barely flows at all. This lava plugs up the plumbing in stratovolcanoes, allowing them to build up tremendous amounts of pressure.
Of all the volcanoes on Earth, stratovolcanoes are the most dangerous. They can erupt with little warning, releasing enormous amounts of material. And they don’t always erupt nicely from their tops. As we saw with Mount Saint Helens, they can blast out material from the side, creating pyroclastic flows the hurtle down the volcano’s flanks at enormous speeds. Some classic eruptions of stratovolcanoes include the island of Krakatoa, which detonated in 1883, sending ash 80 km into the atmosphere.
