Posted on by Fraser Cain

Penumbral Lunar Eclipse, April 24

Image credit: NASA
NASA is planning to send people back to the Moon. Target date: 2015 or so. Too bad they won’t be there this Sunday because, on April 24th, there’s going to be a solar eclipse, and you can only see it from the Moon.

On Earth, solar eclipses happen when the Moon covers the Sun. On the Moon, the roles are reversed. It’s Earth that covers the Sun. Such an eclipse is “a marvelous sight,” according to Apollo 12 astronaut Alan Bean, who saw one in 1969. He was flying home from the Moon along with crewmates Pete Conrad and Dick Gordon when their spaceship flew through Earth’s shadow. “Our home planet [eclipsed] our own star.”

No one will see the April 24th eclipse, but we can imagine what it would be like:

You’re standing on the Moon. It’s broad daylight, almost high noon. The Sun is creeping slowly across the sky. How slowly? A lunar day is about 29.5 Earth-days long. So the Sun moves 29.5 times slower than our Earth-sense tells us it should. At that leisurely pace, the Sun approaches a dark but faintly-glowing disk three times its own size.

The disk is Earth with its nightside facing the Moon. You can see moonlit clouds floating over Earth’s dark oceans and continents. You can also see a faintly glowing ring of light around the planet–that’s Earth’s atmosphere with sunlight trickling through it. A telescope would show you Earth’s city lights, too. Beautiful.

Then the eclipse begins.

Looking through dark-filtered glasses, you watch the Sun slip behind Earth. Earth’s atmosphere, lit from behind, glows red, then redder, a ring of fire the color of sunset, interrupted here and there by the tops of the highest clouds.

Ninety minutes later–patience is required!–only a little bit of the Sun remains poking out over the edge of the planet. Arranged just so, the pair remind you of a giant sparkling diamond ring.

The Sun never completely vanishes because this eclipse is partial, not total. During a total eclipse, Earth would hide the Sun completely, which has the odd effect of turning the Moon blood red. But that’s another story.

Partial eclipses, while not as eerie or dramatic as total eclipses, are still good. In fact, future space tourists will probably rocket to the Moon to see them. It’ll be an exclusive club, people who’ve witnessed Earth taking a bite out of the Sun. The membership in 2005 is only two: Alan Bean and Dick Gordon, the surviving crew of Apollo 12.

Stuck on Earth, what can you do? As a matter of fact, it is possible to observe this Sunday’s solar eclipse from Earth in a roundabout way:

During the eclipse, Earth’s shadow will fall across the Moon and we can see that happen. Our planet’s shadow has two parts, a dark inner core called the umbra and a pale outer fringe called the penumbra. (Aside: Step outside on a sunny day and look at your own shadow. It’s dark in the middle and pale-fuzzy around the edges. You have your own umbra and penumbra.) The Moon on April 24th will glide through Earth’s penumbra, producing what astronomers call a “penumbral lunar eclipse.”

Penumbral eclipses are not easy to see because the penumbra is so pale. If you’re enthusiastic about such things, however, it’s worth a look. A subtle but distinct shading should be visible across northern parts of the Moon during greatest eclipse around 09:55 UT on Sunday morning, April 24th. That’s 02:55 a.m. PDT or 05:55 a.m. EDT in North America. The best place to be is the Hawaiian Islands where the eclipse happens only 5 minutes before local midnight on Saturday, April 23rd. The Moon will be high in the sky, ideally placed.

Even in Hawaii the experience is subtle. Not impressed? You’re just on the wrong world.

Original Source: Science@NASA

Posted on by Fraser Cain

Solar Nebula Lasted 2 Million Years

Image credit: William K. Hartmann/PSI
The oxygen and magnesium content of some of the oldest objects in the universe are giving clues to the lifetime of the solar nebula, the mass of dust and gas that eventually led to the formation of our solar system.
Specimen from the Allende Meteorite

By looking at the content of chondrules and calcium aluminum-rich inclusions (CAIs), both components of the primitive meteorite Allende, Lab physicist Ian Hutcheon, with colleagues from the University of Hawaii at Manoa, the Tokyo Institute of Technology and the Smithsonian Institution, found that the age difference between the two fragments points directly to the lifetime of the solar nebula.

CAIs were formed in an oxygen-rich environment and date to 4.567 billion years old, while chondrules were formed in an oxygen setting much like that on Earth and date to 4.565 billion, or less, years old.

?Over this span of about two million years, the oxygen in the solar nebula changed substantially in its isotopic makeup,? Hutcheon said. ?This is telling us that oxygen was evolving fairly rapidly.?

The research appears in the April 21 edition of the journal Nature.

One of the signatures of CAIs is an enrichment of the isotope Oxygen 16 (O-16). An isotope is a variation of an element that is heavier or lighter than the standard form of the element because each atom has more or fewer neutrons in its nucleus. The CAIs in this study are enriched with an amount of O-16 4 percent more than that found on Earth. And, while 4 percent may not sound like much, this O-16 enrichment is an indelible signature of the oldest solar system objects, like CAIs. CAIs and chondrules are tens of millions of years older than more modern objects in the solar system, such as planets, which formed about 4.5 billion years ago.

?By the time chondrules formed, the O-16 content changed to resemble what we have on Earth today,? Hutcheon said.

In the past, the estimated lifetime of the solar nebula ranged from less than a million years to ten million years. However, through analysis of the mineral composition and oxygen and magnesium isotope content of CAIs and chondrules, the team was able to refine that lifespan to roughly two million years.

?In the past the age difference between CAIs and chondrules was not well-defined,? Hutcheon said. ?Refining the lifetime of the solar nebula is quite significant in terms of understanding how our solar system formed.?

Founded in 1952, Lawrence Livermore National Laboratory has a mission to ensure national security and apply science and technology to the important issues of our time. Lawrence Livermore National Laboratory is managed by the University of California for the U.S. Department of Energy’s National Nuclear Security Administration.

Original Source: LLNL News Release

Posted on by Fraser Cain

Extreme Life in Yellowstone Gives More Hope for Life on Mars

University of Colorado at Boulder researchers say a bizarre group of microbes found living inside rocks in an inhospitable geothermal environment at Wyoming’s Yellowstone National Park could provide tantalizing clues about ancient life on Earth and help steer the hunt for evidence of life on Mars.

The CU-Boulder research team reported the microbes were discovered in the pores of rocks in a highly acidic environment with high concentrations of metals and silicates at roughly 95 degrees F in Yellowstone’s Norris Geyser Basin. The new study shows the microbe communities are subject to fossilization and have the potential to become preserved in the geologic record.

Scientists believe similar kinds of geothermal environments may once have existed on Mars, where astrobiologists have intensified the search for past and present life forms in recent years.

A paper by CU-Boulder doctoral student Jeffrey Walker, postdoctoral fellow John Spear and Professor Norman Pace of CU-Boulder’s molecular, cellular and developmental biology department and the Center for Astrobiology appears in the April 21 issue of Nature.

The research was funded by the National Science Foundation and NASA.

“This is the first description of these microbial communities, which may be a good diagnostic indicator of past life on Mars because of their potential for fossil preservation,” said Walker. “The prevalence of this type of microbial life in Yellowstone means that Martian rocks associated with former hydrothermal systems may be the best hope for finding evidence of past life there.”

Located about 20 miles northwest of Yellowstone Lake, Norris Geyser Basin is considered to be the hottest and most active geyser basin in Yellowstone and perhaps the world. It also is extremely acidic, according to the researchers.

“The pores in the rocks where these creatures live has a pH value of one, which dissolves nails,” said Pace. “This is another example that life can be robust in an environment most humans view as inhospitable.”

The process used to identify the organisms developed by Pace is much more sensitive than standard lab-culturing techniques that typically yield a small, biased fraction of organisms from any environment, said Walker. In this method, the researchers detected and identified organisms by reading gene sequences.

“Each kind of organism has a unique sequence, which is used to map its position in the tree of life,” said Walker. “It’s a family tree of sorts that describes the genetic relationship between all known organisms.”

Walker discovered the new microbe community in 2003 after breaking apart a chunk of sandstone-like rock in the Norris Geyser Basin. “I immediately noticed a distinctive green band just beneath the surface,” he said. “It was one of those ‘eureka’ moments.”

An analysis determined the green band was caused by a new species of photosynthetic microbes in the Cyanidium group, a kind of alga that is among the most acid-tolerant photosynthetic organisms known, said Walker. Cyanidium organisms made up about 26 percent of the microbes identified in the Norris Geyser Basin study by the CU-Boulder team, Walker said.

Surprisingly, the most abundant microbes identified by the team were a new species of Mycobacterium, a group of microbes best known for causing human illnesses like tuberculosis and leprosy, Walker said. Extremely rare and never before identified in such extreme hydrothermal environments, Mycobacterium made up 37 percent of the total number of microbes identified by the CU-Boulder team.

Pace described the new life form in the Norris Geyser Basin as “pretty weird.” “It may well be a new type of lichen-like symbiosis,” said Pace, who won a MacArthur Fellowship, or “genius grant,” in 2001. “It resembles a lichen, but instead of being comprised of a symbiosis between a fungus and an alga, it seems to be an association of the Mycobacterium with an alga.”

While photosynthesis appears to be a key energy source for most of the creatures, at least some Yellowstone microbes are believed to get energy from the dissolved metals and hydrogen found in the pore water of the rock, Walker said. A study by the CU-Boulder team published by the National Academy of Sciences in January 2005 indicated Yellowstone microbe populations living in hot springs at temperatures more than 158 degrees F use hydrogen as their primary fuel source.

The research effort in the Norris Geyser Basin shows that rock formation processes occurring in the hydrothermal environment under study make very real fossil imprints of the organisms embedded in the rock at various stages, showing how the distinctive fossils develop over time, according to the research team.

“Remnants of these communities could serve as ‘biosignatures’ and provide important clues about ancient life associated with geothermal environments on Earth or elsewhere in the Solar System,” the authors wrote in Nature.

Original Source: University of Colorado News Release

Posted on by Fraser Cain

Podcast: Alpha, Still Constant After All These Years

There’s a number in the Universe which we humans call alpha – or the fine structure constant. It shows up in almost every mathematical formula dealing with magnetism and electricity. The very speed of light depends on it. If the value for alpha was even a little bit different, the Universe as we know it wouldn’t exist – you, me and everyone on Earth wouldn’t be here. Some physicists have recently reported that the value for alpha has been slowly changing since the Big Bang. Others, including Jeffrey Newman from the Lawrence Berkeley National Laboratory have good evidence that alpha has remained unchanged for at least 7 billion years.
Continue reading “Podcast: Alpha, Still Constant After All These Years”

Posted on by Fraser Cain

Spitzer Sees an Alien Asteroid Belt

NASA’s Spitzer Space Telescope has spotted what may be the dusty spray of asteroids banging together in a belt that orbits a star like our Sun. The discovery offers astronomers a rare glimpse at a distant star system that resembles our home, and may represent a significant step toward learning if and where other Earths form.

“Asteroids are the leftover building blocks of rocky planets like Earth,” said Dr. Charles Beichman of the California Institute of Technology, Pasadena, Calif. Beichman is lead author of a paper that will appear in the Astrophysical Journal. “We can’t directly see other terrestrial planets, but now we can study their dusty fossils.”

Asteroid belts are the junkyards of planetary systems. They are littered with the rocky scraps of failed planets, which occasionally crash into each other, kicking up plumes of dust. In our own solar system, asteroids have collided with Earth, the moon and other planets.

If confirmed, the new asteroid belt would be the first detected around a star about the same age and size as our Sun. The star, called HD69830, is located 41 light-years away from Earth. There are two other known distant asteroid belts, but they circle younger, more massive stars.

While this new belt is the closest known match to our own, it is not a perfect twin. It is thicker than our asteroid belt, with 25 times as much material. If our solar system had a belt this dense, its dust would light up the night skies as a brilliant band.

The alien belt is also much closer to its star. Our asteroid belt lies between the orbits of Mars and Jupiter, whereas this one is located inside an orbit equivalent to that of Venus.

Yet, the two belts may have one important trait in common. In our solar system, Jupiter acts as an outer wall to the asteroid belt, shepherding its debris into a series of bands. Similarly, an unseen planet the size of Saturn or smaller may be marshalling this star’s rubble.

One of NASA’s future planet-hunting missions, SIM PlanetQuest, may ultimately identify such a planet orbiting HD 69830. The mission, which will detect planets as small as a few Earth masses, is scheduled to launch in 2011.

Beichman and colleagues used Spitzer’s infrared spectrograph to observe 85 Sun-like stars. Only HD 69830 was found to possibly host an asteroid belt. They did not see the asteroids themselves, but detected a thick disk of warm dust confined to the inner portion of the star system. The dust most likely came from an asteroid belt in which dusty smash-ups occur relatively frequently, about every 1,000 years.

“Because this belt has more asteroids than ours, collisions are larger and more frequent, which is why Spitzer could detect the belt,” said Dr. George Rieke, University of Arizona, Tucson, co-author of the paper. “Our present-day solar system is a quieter place, with impacts of the scale that killed the dinosaurs occurring only every 100 million years or so.”

To confirm that the dust detected by Spitzer is indeed ground-up asteroids, a second less-likely theory will have to be ruled out. According to the astronomers, it is possible a giant comet, almost as big as Pluto, got knocked into the inner solar system and is slowly boiling away, leaving a trail of dust. This hypothesis came about when the astronomers discovered the dust around the star consists of small silicate crystals like those found in comet Hale-Bopp. One of these crystals is the bright green-colored gem called forsterite.

“The ‘super comet’ theory is more of a long shot,” Beichman said, “but we’ll know soon enough.” Future observations of the star using Spitzer and ground-based telescopes are expected to conclude whether asteroids or comets are the source of the dust.

Other authors of this study include G. Bryden, T. Gautier, K. Stapelfeldt and M. Werner of NASA’s Jet Propulsion Laboratory, Pasadena, Calif.; and K. Misselt, J. Stansberry and D. Trilling of the University of Arizona.

The Jet Propulsion Laboratory manages the Spitzer Space Telescope mission for NASA’s Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center, at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA. Spitzer’s infrared spectrograph was built by Cornell University, Ithaca, N.Y. Its development was led by Dr. Jim Houck of Cornell.

For artist’s concepts and more information, visit: www.spitzer.caltech.edu/spitzer.

Original Source: Spitzer News Release

Posted on by Fraser Cain

Is There Water on the Moon?

The first object in the night sky most of us ever saw, the Moon remains a mystery. Haunted by poets, looked upon by youngsters in love, studied intensely by astronomers for four centuries, examined by geologists for the last 50 years, walked upon by twelve humans, this is Earth’s satellite.

And as we look towards the Moon with thoughts of setting up a permanent home there, one new question is paramount: does the Moon have water? Although none has been definitely detected, recent evidence suggests that it’s there.

Why should there be water on the Moon? Simply for the same reason that there’s water on Earth. A favorite theory is that water, either as water by itself or as its components of hydrogen and oxygen, was deposited on Earth during its early history–mostly during a period of “late heavy bombardment” 3.9 billion years ago–by the impacts of comets and asteroids. Because the Moon shares the same area of space as Earth, it should have received its share of water as well. However, since it has only a tiny fraction of Earth’s gravity, most of the Moon’s water supply should have evaporated and drifted off into space long ago. Most, but perhaps not all.

In ancient times, observers commonly thought the Moon had abundant water–in fact, the great lava plains like Mare Imbrium were called maria, or seas. But when Neil Armstrong and Buzz Aldrin landed on the Moon in 1969, they stepped out not into the water of the Sea of Tranquillity, but onto basaltic rock. No one was surprised by that–the idea of lunar maria had been replaced by lava plains decades earlier.

As preparations were underway in the mid 1960s for the Apollo program, questions about water on the Moon were barely on the radar screen. Geologists and astronomers were divided at the time as to whether the lunar surface was a result of volcanic forces from beneath, or cosmic forces from above. Grove Carl Gilbert in 1893 already had the answer. That famous geologist suggested that large asteroidal objects hit the Moon, forming its craters. Ralph Baldwin articulated the same idea in 1949, and Gene Shoemaker revived the idea again around 1960. Shoemaker, almost alone among geologists of his day, saw the Moon as a fertile subject for field geology. He saw the craters on the Moon as logical impact sites that were formed not gradually in eons, but explosively in seconds.

The Apollo flights confirmed that the dominant geological process on the Moon is impact-related. That discovery, in turn, ushered in a new question: Since Earth’s water was probably delivered largely by comets and asteroids, could this process have done the same for the Moon? And could some of that water still be there?

In 1994, the SDI-NASA Clementine spacecraft orbited the Moon and mapped its surface. In one experiment, Clementine beamed radio signals into shadowed craters near the Moon’s south pole. The reflections, received by antennas on Earth, seemed to come from icy material.

That makes sense. If there is water on the Moon, it’s probably hiding in the permanent shadows of deep, cold craters, safe from vaporizing sunlight, frozen solid.

So far so good, but… the Clementine data were not conclusive, and when astronomers tried to find ice in the same craters using the giant Arecibo radar in Puerto Rico, they couldn’t. Maybe Clementine was somehow wrong.

In 1998, NASA sent another spacecraft, Lunar Prospector, to check. Using a device called a neutron spectrometer, Lunar Prospector scanned the Moon’s surface for hydrogen-rich minerals. Once again, polar craters yielded an intriguing signal: neutron ratios indicated hydrogen. Could it be the “H” in H2O? Many researchers think so.

Lunar Prospector eventually sacrificed itself to the search. When the spacecraft’s primary mission was finished, NASA decided to crash Prospector near the Moon’s south pole, hoping to liberate a bit of its meager layer of water. Earth’s satellite might briefly become a comet as amounts of water vapor were released.

Lunar Prospector crashed, as planned, and several teams of researchers tried to detect that cloud, but without success. Either there was no water, or there was not enough water to be detected by Earth-based telescopes, or the telescopes were not looking in precisely the right place. In any event, no water was found from Prospector’s impact.

In 2008, NASA plans to send a new spacecraft to the Moon: the Lunar Reconnaissance Orbiter (LRO), bristling with advanced sensors that can sense water in at least four different ways. Scientists are hopeful that LRO can decide the question of Moon water once and for all.

Our interest is not just scientific. If we are indeed to build a base on the Moon, the presence of water already there would offer a tremendous advantage in building and running it. It’s been 35 years since we first set foot on the Moon. Now ambitious eyes once again look toward our satellite not just as a place to visit, but as a place to live.

Original Source: Science@NASA

Posted on by Fraser Cain

Perfect Liquid Hints at Early Universe

Physicists working to re-create the matter that existed at the birth of the universe expected something like a gas and ended up with the “perfect” liquid, four teams of researchers reported at an April 18 meeting of the American Physical Society. One of the teams is led by MIT.

“These truly stunning findings have led us to conclude that we are seeing something completely new–an unexpected form of matter–which is opening new avenues of thought about the fundamental properties of matter and the conditions that existed just after [the Big Bang],” said Raymond Orbach, director of the U.S. Department of Energy’s Office of Science, the primary supporter of the research.

Unlike ordinary liquids, in which individual molecules move about randomly, the new matter seems to move in a pattern that exhibits a high degree of coordination among the particles–something like a school of fish that responds as one entity while moving through a changing environment. That fluid motion is nearly “perfect,” as defined by the equations of hydrodynamics.

Picture a stream of honey, then a stream of water. “Water flows much more easily than honey, and the new liquid we’ve created seems to flow much more easily than water,” said Wit Busza, leader of the MIT team and the Francis Friedman Professor of Physics. Other MIT faculty involved in the work are Professor Bolek Wyslouch and Associate Professor Gunther Roland, both of physics.

Busza notes that the results don’t rule out that a gas-like form of matter existed at some point in the young universe, but the data do suggest “something different, and maybe even more interesting, at the lower energy densities created at RHIC (Relativistic Heavy Ion Collider).”

The research has also led to several other surprises. For example, “there is an elegance we see in the data that is not reflected in our theoretical understanding–yet,” said Roland.

Birth of the universe
About ten millionths of a second after the Big Bang, physicists believe that the universe was composed of a gas of weakly interacting objects, quarks and gluons that would ultimately clump together to form atomic nuclei and matter as we know it.

So, over the last 25 years, scientists have been working to re-create that gas, or quark-gluon plasma, by building ever-larger atom smashers. “The idea is to accelerate nuclei to nearly the speed of light, then have them crash head-on,” Busza said. “Under those conditions the plasma is expected to form.” The current results were achieved at the Relativistic Heavy Ion Collider located at the DOE’s Brookhaven National Laboratory.

RHIC accelerates gold nuclei in a circular tube some 2 kilometers in diameter. In four places the nuclei collide, and around those sites teams of scientists have built detectors to collect the data. The four instruments–STAR, PHENIX, PHOBOS and BRAHMS–vary in their approaches to tracking and analyzing particles’ behavior. The work reported at the APS meeting summarizes the first three years of RHIC results from all four devices. Papers from each team will also be published simultaneously in an upcoming issue of the journal Nuclear Physics A.

MIT is the lead institution for PHOBOS, a collaboration between the United States, Poland and Taiwan. “We are very small,” said Busza, who developed the concept for the device. “STAR and PHENIX each cost about $100 million and have some 400 staff. We cost less than $10 million and have about 50 people,” he said. (BRAHMS is also small.)

Nevertheless, the PHOBOS team got the first physics results from three of the five RHIC experimental runs and tied for first on a fourth. (The fifth run is still being analyzed.)

For one of those runs, the team collected the data, analyzed them and submitted a paper on the work all within five weeks. “That’s unheard of in high-energy physics,” said Busza, who credits Roland with the fast turnaround. “He was the person who managed the extraction of the physics from the data.”

What’s next?
Although the larger RHIC detectors will continue to collect data, PHOBOS has been retired. “From a cost-benefit perspective, we feel we’ve extracted as much knowledge as we can from such a small experiment,” Busza said.

So the team is now looking to the future. The members hope to continue their studies at RHIC’s successor, the Large Hadron Collider (LHC) being built in Europe. That facility will have 30 times the collision energy of RHIC, which will bring the scientists that much closer to the conditions at the birth of the universe. “At LHC we’ll test what we think we learned from RHIC,” Busza said. “We also expect new surprises, perhaps even bigger surprises,” he concluded.

MIT research staff currently involved in PHOBOS are Maarten Ballintijn, Piotr Kulinich, Christof Roland, George Stephans, Robin Verdier, Gerrit vanNieuwenhuizen and Constantin Loizides. Six graduate students are also on the team; the research has already resulted in five theses, with two on the way.

Original Source: MIT News Release

Posted on by Fraser Cain

Audio Feedback?

I’ve just wrapped up my fifth audio interview for Universe Today, and I was hoping to get some feedback from listeners. My goal with this is to focus on specific breaking research and chat with the researchers – it’s very minimalist, though, not a lot of rambling about the weather here at the Cain Cottage in Courtenay. I’ve been having a fun time, and should be able to produce 2-3 of these a week. So, give me any feedback. Who do you want to interviews with? I’m not crazy about the audio quality, and I’ve got my eyes on some new equipment that should improve things greatly.

If you like longer, more in-depth radio interviews, I highly recommend the Space Show, hosted by Dr. David Livingston, which spends 1+ hours talking to a single guest about a range of topics – no subscription link, yet. I can’t believe the quality of guests he’s had on the show in the past, especially this guy. Another great audio show is Slacker Astronomy. They tend to focus on a single topic, and explain it more comprehensively – with silly humour.

I’ve become a huge fan of Podcasting in the last few months (although, I despise the term… we seem to be stuck with it). I love being subscribed to various audio programs, so they just show up on my computer whenever they’ve been updated. It helps to have a portable audio player, but you can just play shows from your computer too; the point is that you’re subscribed. You can download the free subscription software here, and then start subscribing to various Podcast feeds. Here’s what I’m subscribed to: Quirks and Quarks (feed), In Our Time (feed), Reith Lectures (feed). Got any you like? Drop me an email with your suggestions.

Fraser Cain
Publisher
Universe Today

Posted on by Fraser Cain

Low Oxygen Accelerated the Great Dying

The biggest mass extinction in Earth history some 251 million years ago was preceded by elevated extinction rates before the main event and was followed by a delayed recovery that lasted for millions of years. New research by two University of Washington scientists suggests that a sharp decline in atmospheric oxygen levels was likely a major reason for both the elevated extinction rates and the very slow recovery.

Earth’s land at the time was still massed in a supercontinent called Pangea, and most of the land above sea level became uninhabitable because low oxygen made breathing too difficult for most organisms to survive, said Raymond Huey, a UW biology professor.

What’s more, in many cases nearby populations of the same species were cut off from each other because even low-altitude passes had insufficient oxygen to allow animals to cross from one valley to the next. That population fragmentation likely increased the extinction rate and slowed recovery following the mass extinction, Huey said.

“Biologists have previously thought about the physiological consequences of low oxygen levels during the late Permian period, but not about these biogeographical ones,” he said.

Atmospheric oxygen content, about 21 percent today, was a very rich 30 percent in the early Permian period. However, previous carbon-cycle modeling by Robert Berner at Yale University has calculated that atmospheric oxygen began plummeting soon after, reaching about 16 percent at the end of the Permian and bottoming out at less than 12 percent about 10 million years into the Triassic period.

“Oxygen dropped from its highest level to its lowest level ever in only 20 million years, which is quite rapid, and animals that once were able to cross mountain passes quite easily suddenly had their movements severely restricted,” Huey said.

He calculated that when the oxygen level hit 16 percent, breathing at sea level would have been like trying to breathe at the summit of a 9,200-foot mountain today. By the early Triassic period, sea-level oxygen content of less than 12 percent would have been the same as it is today in the thin air at 17,400 feet, higher than any permanent human habitation. That means even animals at sea level would have been oxygen challenged.

Huey and UW paleontologist Peter Ward are authors of a paper detailing the work, published in the April 15 edition of the journal Science. The work was supported by grants from the National Science Foundation and the National Aeronautics and Space Administration’s Astrobiology Institute.

Not only was atmospheric oxygen content dropping at the end of the Permian, the scientists said, but carbon dioxide levels were rising, leading to global climate warming.

“Declining oxygen and warming temperatures would have been doubly stressful for late Permian animals,” Huey said. “As the climate warms, body temperatures and metabolic rates go up. That means oxygen demand is going up, so animals would face an increased oxygen demand and a reduced supply. It would be like forcing athletes to exercise more but giving them less food. They’d be in trouble.”

Ward was lead author of a paper published in Science earlier this year presenting evidence that extinction rates of land vertebrates were elevated throughout the late Permian, likely because of climate change, and culminated in a mass extinction at the end of the Permian. The event, often called “the Great Dying,” was the greatest mass extinction in Earth’s history, killing 90 percent of all marine life and nearly three-quarters of land plants and animals.

Ward said paleontologists had previously assumed that Pangea was not just a supercontinent but also a “superhighway” on which species would have encountered few roadblocks while moving from one place to another.

However, it appears the greatly reduced oxygen actually created impassable barriers that affected the ability of animals to move and survive, he said.

“If this is true, then I think we have to go back and look at oxygen and its role in evolution and how different species developed,” Ward said. “You can go without food for a couple of weeks. You can go without water for a few days. How long can you go without oxygen, a couple of minutes? There’s nothing with a greater evolutionary effect than oxygen.”

Original Source: UW News Release

Posted on by Fraser Cain

The Search for the Mountain of Eternal Sunlight

ESA?s SMART-1 mission to the Moon has been monitoring the illumination of lunar poles since the beginning of 2005, about two months before arriving at its final science orbit.

Ever since, the AMIE on-board camera has been taking images which are even able to show polar areas in low illumination conditions. Images like these will help identify if peaks of eternal light exist at the poles.

SMART-1 took views of the North Polar Region from a distance of 5000 km during a pause in the spiralling descent to the science orbit. One can see highland terrains, very highly cratered due to their old age. The rims of the large craters project very long shadows even on surrounding features. SMART-1 is monitoring the polar shadows cast during the Moon rotation, and their seasonal variations, to look for places with long-lasting illumination.

The image shows a 275 km area close to the North pole (upper left corner) observed by SMART-1 on 29 December 2004 from a distance of 5500 km. This shows a heavily cratered highland terrain, and is used to monitor illumination of polar areas, and long shadows cast by large crater rims.

SMART-1 also observated a North polar area 250 km wide on 19 January 2005 (close to North winter solstice) from a distance of 5000 km. The illuminated part of crater rim is very close to the North pole and is a candidate for a peak of eternal sunlight.

?This shows the ability of SMART-1 and its camera to image even for low light levels at the poles and prospect for sites for future exploration?, says AMIE camera Principal Investigator Jean-Luc Josset, (SPACE-X, Switzerland).

?If we can confirm peaks of eternal light?, adds Bernard Foing, SMART-1 Project Scientist, ?these could be a key locations for possible future lunar outposts?.

The existence of peaks of eternal light at the poles, that is areas that remain eternally illuminated regardless of seasonal variations, was first predicted in the second half of the nineteenth century by the astronomer Camille Flammarion. Even if for most of the Moon the length of the day does not vary perceptibly during the course of seasons, this is not the case over the poles, where illumination can vary extensively during the course of the year. The less favourable illumination conditions occur around the northern winter solstice, around 24 January. There are areas at the bottom of near-polar craters that do not see direct sunshine, where ice might potentially be trapped. Also there are areas at higher elevation on the rim of polar craters that see the Sun more than half of the time. Eventually, there may be areas that are always illuminated by sunlight.

Original Source: ESA News Release