Bright Spot on Venus Stumps Scientists

By Andrea Thompson, Senior Writer @ liveScience.com

A sudden bright spot that appeared in the clouds of Venus just days after a comet left a bruise on Jupiter has scientists stumped as to its cause.

Venus' bright spot, first noticed by amateur astronomer Frank Melillo of Holtsville, NY on July 19, is not the first such brightening noticed on our cloudy neighbor, said planetary scientist Sanjay Limaye of the University of Wisconsin-Madison.

"We have seen such events before," he told SPACE.com.

This time is a little different though because the brightening is confined to a smaller region, Limaye said. It also came in the wake of Jupiter's own new (dark) spot, believed to be the result of a comet impact — Limaye attributes the fortunate confluence of the two events for the attention Venus is now getting in the astronomical community.

After Melillo reported the spot, other amateur astronomers and the European Space Agency's (ESA) Venus Express spacecraft confirmed the presence of the blemish.

The new Venus Express images show that the bright spot actually appeared in the planet's southern hemisphere four days before Melillo saw it and that it has since begun to spread out, becoming stretched by the wind's in Venus' thick atmosphere.

But just what caused the brightening is still a mystery. Theories have abounded, from a volcanic eruption to solar particles interacting with the planet's atmosphere.

Limaye says the volcano explanation is unlikely, for several reasons: Volcanoes on Venus seem to be less likely to blow their tops in Mount St. Helens-type fashion, instead behaving more like the oozing lava factories of Hawaii, so their eruptions wouldn't likely produce huge clouds of ash and steam. Also, it is unlikely that the explosions would have the power to push through to the other layers of Venus' extremely dense atmosphere.

Limaye doesn't completely rule out the possibility, however. "It's possible, we just don't know," he said.

Another explanation is that a coronal mass ejection (an energetic plume of plasma from the sun's corona) or the solar wind could have interacted with the clouds of Venus.

These "could cause something, we don't know what," Limaye said.

Yet another possibility is some internal change in Venus' atmosphere that could alter cloud particles and make them more reflective (and therefore brighter as viewed from space).

"Clearly something in the cloud properties changed," Limaye said.

Even though these events have been seen previously, most notably in Jan. 2007, our limited knowledge about the workings of Venus' atmosphere and lack of enough spacecraft to comprehensively study the planet hasn't narrowed down the list of possible causes, Limaye said.

"Right now, I think it's anybody's guess," he said.

Scientists Claim New State of Matter Created

By LiveScience Staff

Scientists claim to have created a form of aluminum that's nearly transparent to extreme ultraviolet radiation and which is a new state of matter.

It's an idea straight out of science fiction, featured in the movie "Star Trek IV."

The work is detailed in the journal Nature Physics.

The normal states of matter are solid, liquid and gas, and a fourth state, called plasma, is a superheated gas considered more exotic. Other experiments have created strange states of matter for brief periods. This one, too, existed only briefly.

To create the new, even more exotic stuff, a short pulse from a laser "knocked out" a core electron from every aluminum atom in a sample without disrupting the metal’s crystalline structure, the researchers explain.

''What we have created is a completely new state of matter nobody has seen before," said professor Justin Wark of Oxford University’s Department of Physics.

"Transparent aluminum is just the start," Wark said. "The physical properties of the matter we are creating are relevant to the conditions inside large planets, and we also hope that by studying it we can gain a greater understanding of what is going on during the creation of 'miniature stars' created by high-power laser implosions, which may one day allow the power of nuclear fusion to be harnessed here on Earth."

Fusion is a dream of scientists who would create cheap and plentiful power by fusing atoms together, as opposed to nuclear fission that generates electricity today.

The discovery was made possible with a high-powered synchrotron radiation generator called the FLASH laser, based in Hamburg, Germany. It produces extremely brief pulses of soft X-ray light, each of which is more powerful than the output of a power plant that provides electricity to a whole city.

The Oxford team, along with their international colleagues, focused all this power down into a spot with a diameter less than a twentieth of the width of a human hair. At such high intensities the aluminum turned transparent.

While the invisible effect lasted for only an extremely brief period – an estimated 40 femtoseconds – it demonstrates that such an exotic state of matter can be created using very high power X-ray sources.

"What is particularly remarkable about our experiment is that we have turned ordinary aluminum into this exotic new material in a single step by using this very powerful laser," Wark said. "For a brief period the sample looks and behaves in every way like a new form of matter. In certain respects, the way it reacts is as though we had changed every aluminum atom into silicon: it’s almost as surprising as finding that you can turn lead into gold with light."

How world currencies have faired

Dark Matter Helped Early Galaxies Survive "Massacre"

By Ker Than
for National Geographic News

The "ignition" of the first stars half a billion years after the big bang led to a cosmic massacre that spared just one out of every thousand galaxies. Survival depended on having large clouds of the mysterious substance known as dark matter, a new supercomputer model suggests.

Within dark matter clouds, normal matter was in the process of coalescing into young stars.

These stars, however, would have been sending out damaging radiation.

Larger dark matter clouds would have attracted more normal, or visible, matter, which means that larger galaxies would have had enough material to survive even after being blasted by radiation from their neighbors.

Smaller galaxies, meanwhile, would have had all their stars and star-forming material vaporized, leaving behind barren dark matter clumps.

"This is a case where the bullies really win out," said study team member Carlos Frenk, an astrophysicist at Durham University in the U.K.

"The galaxies that managed to make the stars that fried the early universe were the ones that managed to accumulate dark matter the fastest."

"Missing" Satellites

For a long time after the galactic massacre, no new galaxies were able to form, according to the new simulations by Frenk and Takashi Okamoto of the University of Tsukuba in Japan.

Dark matter, meanwhile, continued to merge and grow into ever larger structures.

Then, around 10 to 12 billion years ago, some of the dark matter clumps grew massive enough to counteract the radiation from the survivor galaxies.

At this point the dark matter could once again "protect" normal matter, and larger galaxies were finally able to take shape.

This model, recently presented at the Royal Society 2009 Summer Science Exhibition in London, could explain the Milky Way's "missing satellite" problem, said astrophysicist Andrew Benson of the California Institute of Technology.

So far, astronomers know of only about 20 satellite galaxies of the Milky Way, but according to a key theory of galaxy formation, there should be thousands.

That's because big galaxies like the Milky Way are thought to have formed through the violent mergers of many smaller galaxies.

Any discarded remnants that didn't make it into the larger structure would have become satellite galaxies.

But if the new model is correct, then the Milky Way's "missing" satellite galaxies never formed in the first place, said Benson, who was not involved in the new study.

"Professor Frenk has shown that if you can prevent the formation of galaxies very early in the universe, you can reduce the number of galaxies that you would expect to see around the Milky Way down to a level that is more compatible with what we actually observe."

How we spend our paycheck

Cosmic Ray Moon Shadow Could Reveal Dark Matter

by technologyreview.com

If a strange excess of positrons hitting Earth are created by dark matter, then the way the Moon blocks these impacts could help confirm the idea

The Earth is constantly bombarded by high energy positrons and electrons. These bombardments generate showers of secondary particles that light up our skies at night, if you have the right equipment to see 'em: so-called Imaging Atmospheric Cherenkov Telescopes. The ratio of electrons to positrons is predicted fairly precisely by our models of the way cosmic rays interact with objects in the Milky Way.

But here's a conundrum. Various space-based experiments such as PAMELA have recently found an excess of positrons out there, particularly at energies above 10 GeV. That's totally unexpected and difficult to square with the conventional model.

The PAMELA measurement generated excitement because the dark matter brigade pounced on the result as evidence that dark matter particles must annihilating each other, producing the excess positrons in the centre of our galaxy. These guys were forced to put the champagne back on ice when other astrophysicists pointed out that the positrons could equally be created by particle cascades in the magnetospheres of nearby pulsars.

What's needed, of course, is more measurements of positron/electron ratios, particularly at energies up to a few TeV that cannot yet be made by space-based experiments.

Can the growing number of Imaging Atmospheric Cherenkov Telescopes help? On the face of it, that looks unlikely because there is no way to tell apart the showers created by positrons and electrons when they hit the atmosphere. At least, until now.

Today, Pierre Colin and pals at the Max-Planck-Institut fur Physik in Munich have come up with an ingenious idea that should be able to tell them apart. Most of the electrons and positrons come from the galactic centre. Colin and co point out that that when the Moon comes between us and the electron/positron source, it creates a shadow that is already used to calibrate Imaging Atmospheric Cherenkov Telescopes.

But here's the interesting idea: Colin and co say the shadow of charged particles should be deflected by the Earth's magnetic field. The electron shadow should be shifted eastward and the positron shadow westward. These Imaging Atmospheric Cherenkov Telescopes should therefore be able to spot the separate shadows, allowing the measurement of positron/electron ratios at energies up to several TeV, well beyond what space-based experiments can achieve.

What's more, Imaging Atmospheric Cherenkov Telescopes ought to be able to spot these shadows now as long as they can make measurements in the glare of the Moon. One such instrument called MAGIC, built by the Max-Planck-Institut fur Physik at Roque de los Muchachos in the Canary islands, exactly fits the bill.

The measurements will still be tricky however, particularly of the positron shadow which may well be superimposed on the shadow created by positively charged atoms in the cosmic ray spectrum. However, Colin and co think they ought to be able to pick out the electron shadow with just 50 hours of observing (although that may take several years given that the shadows occur only at certan times of the year).

That's an ingenious idea that may well give astronomers a way of determining what role dark matter plays, if any, in the creation of these excess positrons.

Ref: arxiv.org/abs/0907.1026: Observation of Shadowing of the Cosmic Electrons and Positrons by the Moon with IACT

How the Hubble Deep Field was Taken

Are Planets "Living Super-Organisms"?

by Casey Kazan

Japan's Maruyama Shigenori, one of the world's leading geophysicists, is working on a global formula for a new field of study that would include dozens of disciplines collaborating to produce an overall picture of the Earth. As he connects the links from astronomy to life sciences, an outline emerges of an all-encompassing image of entire planets which appear as living super-organisms.

Shigenori believes that expanding the study of life sciences to the core of our world and the depths of outer space will help us find distant relatives of our own Earth -- planets that could also sustain life.

Maruyama is creating a new institute called the Center for Bio-Earth Planetology will be launched in 2009 and fully dedicated to creating a new conception of life in space.He wants to find out if the continents will merge again in 250 million years to form a single super-continent; how meteorites change the chemical composition of the Earth; and what the connection is between the temperature of a planet and its magnetic field, which protects plants and animals from being bombarded with cosmic radiation, which in turn influences the rate of mutations and thus the development of new forms of life.

Maruyama is also provoking controversy in the with his new theory on the lifecycle of the Earth's crust.

To explain why contintental plates drift on the surface of the Earth's molten mantle, Maruyama argues that continents actually have life cycles. Old, cold plates on continental fringes sink to “plate graveyards” deep in the Earth’s mantle, and then rise again, creating volcanoes fueled by three-dimensional convection movements deep below the surface.

Maruyama is taking the ideas of continental-drift pioneer Alfred Wegener to a new level. Wegener was a German explorer and meteorologist who believed back in 1912 that the continents roamed about on the surface of the Earth -- an idea that was ridiculed by even his most supportive research colleagues as a "delirious vision" and "the wonderful dream of a great poet." It wasn't until the 1960s that studies of the ocean floor finally provided irrefutable proof that Wegener had been right after all.

Today, we all know that the continents are enormous plates that drift on the Earth's red-hot mantle like icebergs on the ocean. Yet to this day, the hypothesis still lacks a logical and convincing foundation. Nobody has been able to explain the actual mechanics behind the motor that drives the drifting and breaking-up of the continental plates.

The inner reaches of the Earth remain shrouded in mystery. Even the surface of has been explored more extensively. Because deep drilling comes to a halt after a maximum of 12 kilometers, the remaining 6,300 kilometers to the center of the Earth remain inaccessible.

In an interview with Der Spiegel, Maruyama gave the answer: "The continental drift that we observe on the surface of the Earth has its counterpart in the Earth's mantle. Old, cold plates are pushed down into the Earth's mantle on the continental edges," he explains. "At this point they collect large amounts of iron. You can imagine it as something similar to water condensation."

Weighted down by the iron, the plates sink farther and farther into the hot, molten rock until they reach the inner sanctum of the Earth's mantle. There, at a depth of 2,900 kilometers, they finally halt their decent and settle into "plate graveyards." This is presumably the outer edge of the earth's heavy core, where the temperature is 4,000 degrees Celsius (7,200 degrees Fahrenheit).

Maruyama continues: "But the capsized continents don't simply rest in their plate graveyards forever." Rather, they are about to experience a sudden resurrection. Heat and pressure in the depths trigger chemical processes, causing the plates to deposit their load of heavy elements. Once liberated of this burden, they become lighter than their surroundings, causing them to rise like corks in water. The result: Above the old plate graves, on the floor of the Earth's molten mantle, a mushroom-shaped upwelling of abnormally hot magma called a mantle plume makes its way toward the surface.

Eventually, the rising flow of molten rock reaches the crystallized crust and cuts through it like a welding torch. Volcanoes form, such as those on the Big Island of Hawaii.

Maruyama says the red hot lava that erupts on the volcanic island comes directly from an old plate cemetery 2,900 kilometers below the surface, where the remains of an ancient continent that broke up some 750 million years ago simmer to the surface. Maruyama's theory postulates the amazing comeback story of this ancient rock from the deep.

The key ingredient for the chemistry of the Earth's interior is the same one that determines the weather on the surface: water. The sunken ocean plates have old seawater locked in their mineral structure -- only a few parts per thousand, but enough to drastically change the characteristics of the rock.

Even minute quantities of water in the ex-floor of the ocean can significantly lower its melting point -- and this speeds up its eventual return to the surface. The water helps the rock to lose its load of heavy iron, thereby increasing the buoyancy of this old plate material.

The geophysicist thus paints a three-dimensional picture of the planet Earth where, in addition to the continents drifting on the surface, there is room for "anti-plate tectonics" at the base of the Earth's mantle. An "anti-crust" deep below reflects to a certain degree events on the surface, with "lakes" and "mountains" and "rivers" of viscous molten rock.

Earthquakes and computing power are the main requirements for researchers looking to piece together an x-ray-like image of the Earth's interior. The principle is simple enough: When an earthquake strikes, the seismic waves race clear across the Earth's mantle. It takes a full quarter of an hour for the shockwave to travel from Indonesia to Germany. The duration of this journey reveals a great deal to researchers. The waves are slowed down by viscous and hot regions, like mantle plumes, and accelerated by solid or cold objects.

Earthquakes similar to the one that hit Kobe in 1995 and killed nearly 5,100 Japanese -- are Maruyama's main source of data. The island nation lies directly on the West Pacific crossroads of three huge plates that ram into each other like cars in a highway pile-up: the Pacific, Australian and Eurasian tectonic plates.