20
April
2007
20-Apr-2007 A new undersea chimney emitting hot springs of iron-darkened water – a black smoker – has been discovered 8,500 feet down in the Pacific Ocean off Costa Rica. Living there the scientists have found a pink form of the jellyfish order stauromedusae, which may be a new species. The jellyfish looks a bit like Medusa, the serpent-haired monster of Greek mythology, said expedition leader Emily Klein. So they have now named this part of the sea-floor the Medusa Hydrothermal Vent Field.
12-Apr-2007 Scientists have reported one of the world’s greatest mass death of corals, caused directly by the earthquake in Indonesia on 28 March 2005.
2-Apr-2007 A high-tech villa, designed to resist earthquakes by self-healing cracks in its walls and monitoring vibrations through intelligent sensors, will be built on a Greek mountainside.
29-Mar-2007 Scientists show that lightning is a good indicator of volcanic activity by observing “spectacular lightning sequences” at Mount Augustine, Alaska.
4-Dec-2006 Tsunami story and science teaching resources (US or UK English) posted at www.realscience.org.uk
Posted under News updates
19
April
2007
19-Apr-2007 A new study of dark matter haloes shows they are shaped like frisbees, not rugby balls as had been suggested.
3-Apr-2007 Scientists propose a new model of large-scale gravitation in which the force on dark matter is different to that experienced by normal matter.
The Abnormally Weighting Energy hypothesis achieves a number of scientifically satisfactory outcomes: It agrees well with observation, particularly of distant supernovae. It does not require negative pressures. It predicts an age of the universe 3 billion years greater than current models. And unlike previous theories of dark matter, it does not lead to an exponentially expanding universe, but rather a normal Einstein-de Sitter space, in which expansion is slowed by gravitation.
Best of all, AWE explains with minimal change to existing physics the otherwise deeply mysterious “dark energy”.
4-Dec-2006 Observations from Hubble Space Telescope show that dark energy has been speeding up the expansion of the universe for the largest part of its existence. Story and science teaching resources (US or UK English) posted at www.realscience.org.uk
Posted under News updates
18
April
2007
18-Dec-2006 How does a school of fish or flock of birds know how to move instantly from one pattern to another? New research from the University of Alberta shows how movements by a single individual ripple through the whole group.
18-Dec-2006 Flotillas of smart dust particles could be the first emissaries from Earth to visit extra-solar planets. Story and science teaching resources (US or UK English) posted at www.realscience.org.uk
Posted under News updates
18
April
2007
Teaching resources (UK US) designed specifically for this story at Real Science
The story
Tiny, shape-shifting devices that are carried on the wind like dust, but are smart enough to communicate, fly in formation and take scientific measurements. Sounds like science fiction? Not at all, say engineers at the University of Glasgow, who are designing a new breed of planet explorers.
Smart dust particles contain a computer chip one millimetre across. This is surrounded by a polymer sheath that a small voltage can make wrinkled or smooth.
Roughening the surface makes the drag on the smart dust particle increase and it floats higher in the air. Smoothing out the surface causes the particle to sink. Simulations show that by switching between rough and smooth, the smart dust particles can hop towards a target.
Professor John Barker will talk about possible applications of smart dust at the RAS National Astronomy Meeting in Preston today, 18 April. “The concept of using smart dust swarms for planetary exploration has been talked about for some time,” he said.
“But this is the first time anyone has looked at how it could actually be achieved. Computer chips of the size and sophistication needed to make a smart dust particle now exist.”
He and his team are studying a variety of polymers to find one that can give a large deformation for a small voltage, he added.
Smart dust particles would use wireless to communicate with each other and form swarms, Professor Barker explains. Most particles in the swarm can only talk to their nearest neighbours. But a few can communicate at much longer distances.
“In our simulations we’ve shown that a swarm of 50 smart dust particles can organise themselves into a star formation, even in turbulent winds.
“The ability to fly in formation means that the smart dust could form a phased array. It would then be possible to process information between the distributed computer chips, and collectively beam a signal back to an orbiting spacecraft.”
For smart dust to explore a planet, the particles need to carry sensors. Today’s chemical sensors are too big for the thin Martian atmosphere. This could only support particles the size of sand grains.
But the atmosphere of Venus is much denser. It could carry smart sensors up to a few centimetres in size. “Scientific studies could theoretically be carried out on Venus using the technology we have now,” says Professor Barker.
“However miniaturisation is coming on rapidly.”
By 2020 chips will be available with components just a few nanometres across, he said. “This means our smart particles would behave more like macro-molecules diffusing through an atmosphere, rather than dust grains.”
The Glasgow group believes it will be some years before smart dust is ready to be launched into space. “We are still at an early stage, working on simulations and components,” said Professor Barker. “We have a lot of obstacles to overcome before we are even ready to physically test our designs.
“However, the potential applications of smart dust for space exploration are very exciting. Our first close-up studies of extra-solar planets could come from a smart dust swarm delivered to another solar system by ion drive.”
Topics for group discussion or pupil presentations
1. Figuring out exactly what scientists have been doing on the basis of news stories is often quite difficult. A useful starting point is an activity that asks students to classify the different types of statement in a story. In groups students should look for all the occurrences of just two types of statement in this story: a) technology and methods used by the scientists, and b) new findings or developments they have made.
Students should then try to answer the following questions:
- In as much detail as possible, what do these Glasgow scientists actually do when they come into work each day?
- How has what they have been doing made the manufacture of smart dust more likely?
2. In groups, students should assess the merits of manned versus unmanned space exploration. Human spaceflight is costly, dangerous, and a complete waste of time and money, say critics. Supporters point out that the urge to explore is part of what makes us human. The key difference between people and robots (including smart dust) in space is that we care about people. It is hard to identify with the adventures of dust, no matter how smart it might be. So space exploration needs people up there to win support and funding from governments and the general unscientific public. Discuss.
3. One of the most astonishing sights in nature is a flock of starlings at evening-time, flying in formation, swooping and swirling in mesmerising patterns that seem to be controlled by just one mind. It’s one example of a phenomenon called emergent behaviour, which is quite widespread in the natural world. The scientists in this story are aiming to exploit the emergent behaviour of smart dust particles.
Students should find as many examples in the natural world as they can, and prepare a short presentation which touches on how one controlling mind can seem to emerge when individuals communicate only with their nearest neighbours.
Links to free activities, resources and lessons
This story is about science just beyond the limits of today’s technology, so the Web offers few relevant classroom activities. The following is a set of sources of accessible information on smart dust and its applications.
Professor Barker on smart dust research at Glasgow University. Includes entries on space applications, shape changing and the analogy with blown sand.
City-swallowing sand dunes. Nice illustrated story and audio of how particles of sand move by a method known as saltation. This is the most likely mode of travel for the first generation of smart dust.
“Swarms of smart dust might be packed into nose cones of planetary probes and subsequently ejected into the atmosphere of a planet where they would be carried by the wind. For a planet such as Mars smart dust motes would each be of the size of a grain of sand.” From Professor Barker’s website.
Notes and thoughts on a smart dust project at Berkeley.
Website of a company set up to commercialise smart dust.
“We have considered the collective movement of motes towards a target located in a portion of the Martian surface that extends over a range of several kilometres.” Professor Barker again.
The smart dust project. “Smart dust was developed by Kris Pister, Joe Kahn, Bernhard Boser at the University of Berkley, California, between 1998 and 2001 with the aim of demonstrating a complete sensor/communication system that can be integrated into a cubic millimetre package.” Glasgow University is a member of a large consortium dealing with a practical variant called Smart Specks.
Daily tip for science class discussions and groupwork
Listening to each other is not merely a matter of being quiet when another person speaks; listening requires a response to what is being said. Teachers could develop procedural guidelines to give structure to group talk so that children become used to questioning and challenging each other. The consistency in performance of one group in the study suggests that the children may have developed certain ground rules for the argumentation process, as they knew how to work together collaboratively. The inconsistent performance shown by other groups suggests that although they were capable of high levels of argumentation, they had no such ground rules. If children are able to scaffold small-group discussions themselves then the teacher input could be directed towards children who are not yet capable of doing this.
Simon, S. and Maloney, J. (2007) Activities for promoting small group discussion and argumentation. School Science Review, 88 (324), pp. 49-57
Posted under Technology
17
April
2007
Teaching resources (UK US) designed specifically for this story at Real Science
The story
Scientists at Washington University, with the help of a keen-eyed student, are paving the way for the Phoenix Mission to make a smooth landing on Mars.
The team has been analysing images of the surface of the red planet. Their aim is to make sure the Phoenix, which is due to launch in August, lands in a rock-free spot on the northern plains of Mars.
The craft has to land in a place that won’t have steep slopes or big rocks, said Raymond Arvidson, professor in arts and sciences, and chair of the Washington University earth and planetary sciences department.
“We’ve been looking for locations big enough and homogeneous enough for a high probability of a successful landing. The issue isn’t slopes. The issue is rocks.”
If the lander came down in a place with rocks as big as itself, the whole craft could tilt or tip over. Another problem is the craft’s solar panels. Big rocks would stop these unfurling. Without solar power, which drives seven Phoenix mission instruments, there isn’t much of a mission.
At the heart of the painstaking task of finding a smooth landing is a 21-year-old student at Washington University. Tabatha Heet began working with Arvidson as a work-study student in 2005. She started counting Martian rocks in October 2006.
“Ray asked if I would count some rocks in the original landing area, and I got started, thinking it was going to be a one-time thing,” said Heet. “But it’s turned into a big project. I’ve counted thousands of rocks now.”
Arvidson and his colleagues had settled on a region called Region B for the future landing. But images from an instrument called HIRISE, a feature of the Mars Reconnaissance Orbiter Mission, made them think again.
“The first images for Region B were scary,” Arvidson said. “There are rocks there bigger than the lander – too many big rocks sitting on craters to fit in a landing site.”
With the help of HIRISE images, they looked elsewhere. Heet produced data on the abundance of rocks at different places on the northern plains. This allowed the mission scientists to “zero in on the safe havens”, Arvidson said.
Heet used a software package called ENVI. This shows images and makes measurements.
“All you have to do is draw a line on the image,” she said. “Then ENVI will tell you how long the line is in meters. I go through the image and pick just a small area, because the HIRISE images are too big for one person to count. I’ll make a little subset and then go count every rock in the subset, just by drawing a line where I see the shadow of the rock.
“It’s very slow and makes your eyes go crazy.”
She counted rocks in little areas of the large images. She then made cumulative frequency plots. These showed the number of rocks bigger than any given diameter.
Heet flew out to the Jet Propulsion Laboratory in February. She received a warm round of applause at her introduction to JPL researchers. They questioned her on her technique and stamina. Later, she met a team of automated rock counters who “aggressively” questioned the way she had been counting rocks.
At the meeting, the automated rock counters calibrated their computed numbers to Heet’s hand counts. They are considered ‘ground truth,’ on which all later data are based. She has since corresponded with the group regularly to help make the automated counts more precise.
The automated rock counters map the shape of the shadows, said Arvidson. “From knowing where the sun is, they can compute the rock height and width.
“But they need very intense validation. Tab was the point contact for all of that. We’ve cross-calibrated against the automated counts, because the hand-derived ones are considered anchors.
A human can do a better job with fewer errors “as long as the person is not fatigued”, he added.
Heet’s work has led to the discovery of several possible landing sites. These have at least ten times fewer rocks than the original Region B. They include one desirable location 50 kilometres wide and 250 meters deep. The scientists call it Green Valley.
As data come in from the actual mission, Heet will be at JPL, gathering and interpreting the data, Arvidson said. Just as former Rhodes scholar Bethany Ehlmann, now pursuing a PhD at Brown University, did for the Mars Exploration Rover.
After all her dedicated, painstaking work, Heet often thinks of the mission and the thrill of the Phoenix launch and landing.
“I will certainly be excited when Phoenix launches. I will also probably feel a little bit of pride knowing that I helped make the launch possible. I suspect I’ll be slightly nervous when Phoenix is landing, wondering if I did something wrong and am going to be responsible for making Phoenix crash in a field of huge boulders. Once the lander is on the surface it will be interesting to find out just how accurate all of our predictions were.
“I’m looking forward to it all.”
Topics for group discussion or pupil presentations
1. Research and present current and past thinking about the chances of finding life on Mars.
2. In groups discuss what effect the discovery of life on other planets would have on how people think about science. Would the subject become more popular? Would religions with their view that humans are special disappear? Would the answers to these two questions be different if the extraterrestrial life we discovered were intelligent beings like us or “just” micro-organisms?
3. There are now scientists called astrobiologists who aim to discover if there is life on other planets, by analysing the light that comes from them. Amazingly they are working towards doing this for planets around other stars, as well as in our own solar system. Separating the light of these “exoplanets” and the light of their star has been compared to separating a candle 1000 kilometres away from a lighthouse beside it. Students should read the interview with Giovanna Tinetti then discuss and explain what an astrobiologist actually does.
Links to free activities, resources and lessons
Phoenix mission homepage. Scheduled for launch in August 2007, the Phoenix Mars Mission is designed to study the history of water and habitability potential in the Martian Arctic’s ice-rich soil.
The Phoenix Classroom. Activities and materials to aid understanding of fundamental concepts in science, technology, engineering and mathematics. Includes programs for teacher and student participation.
Ask the Phoenix Mars Mission team a question.
“Spacecraft visiting Mars have returned intriguing images of the surface of the Red Planet for over forty years. Many of these images suggest liquid water once flowed on the surface of Mars. The online video Mars: The Search for Water, the Search for Life looks at some of these images, compares them to similar features on Earth, and looks at the consequences of finding liquid water on Mars.
Phoenix mission fact sheet.
Introduction to what we know and hope to discover about Mars. Learn about the Red Planet by comparing similarities and differences to Earth.
The Phoenix Student Interns Program is an opportunity for high school teachers and students to become part of the science team for the 2007-2008 Phoenix Mars Lander Mission. Selected teachers and students will work with scientists to prepare for surface operations on Mars, analyse data during the mission, and reach out to other students, teachers, and the public through presentations, articles, and web sites. Apply by April 25, 2007
Learn how to organise data in a cumulative frequency table.
Design, construct and test an original model of a bouncing lander. Hold a classroom contest to see which landers work best to keep the cargo from breaking.
Links to more links
Space games and quizzes.
Daily tip for science class discussions and groupwork
Only exceptional lecturers are capable of holding students’ attention for an entire lecture period. It is even more difficult to provide adequate opportunity for students to critically think through the arguments being developed. Consequently, lectures simply reinforce students’ feelings that the most important step in mastering the material is memorizing a zoo of apparently unrelated examples.
In order to address these misconceptions about learning, we developed a method, Peer Instruction, which involves students in their own learning during lecture and focuses their attention on underlying concepts. Lectures are interspersed with conceptual questions, called ConcepTests, designed to expose common difficulties in understanding the material. The students are given one to two minutes to think about the question and formulate their own answers; they then spend two to three minutes discussing their answers in groups of three to four, attempting to reach consensus on the correct answer. This process forces the students to think through the arguments being developed, and enables them (as well as the instructor) to assess their understanding of the concepts even before they leave the classroom.
From Peer Instruction
Posted under Physics
14
April
2007
14-Apr-2007 A new model of the physics of neutron stars helps explain the ’superbursts’ of X-rays that these exotic collapsed stars (one teaspoon of which weighs a billion tons) emit much more regularly than previous models predicted.
9-Apr-2007 When it comes to eerie astrophysical effects, magnetars are hard to beat. News story and science teaching resources (US or UK English) posted at www.realscience.org.uk
Posted under News updates
12
April
2007
Teaching resources (UK US) designed specifically for this story at Real Science
Previous dinosaur story and teaching resources (UK US) in the Real Science archives.
The story
Scientists have sequenced tiny pieces of protein from a 68 million-year-old Tyrannosaurus rex. The fragments seem to closely match those found in today’s chickens. This supports a recent theory that birds are descended from dinosaurs.
Scientists at Harvard Medical School, Beth Israel Deaconess Medical Center and North Carolina State University did the research. They report it in the April 13 issue of Science.
It is widely believed that birds evolved from dinosaurs, said John Asara. He is director of the mass spectrometer facility at Beth Israel Deaconess Medical School. “But that’s all based on the architecture of the bones.”
Asara sequenced the protein fragments – seven of them – over the course of a year and a half. His team used sensitive mass spectrometry methods. “This allows you to get the chance to say, ‘Wait, they really are related because their sequences are related.’”
The researchers did not get enough sequences to definitely say that, he added. “But what sequences we got support that idea.”
In another study in the same issue of Science, researchers report that extracts of T. rex bone reacted with antibodies to chicken collagen. This further suggests the presence of birdlike protein in the dinosaur bones.
This work was done by Mary Schweitzer and colleagues at North Carolina State University.
The mere existence of such ancient protein contradicts a long-held belief. When an animal dies, protein begins to degrade immediately. It is slowly replaced by mineral when fossils form.
This process was thought to be complete in one million years.
For centuries it has been believed that fossilisation destroyed any original material, said Schweitzer. She is also at the North Carolina Museum of Natural Sciences and is a co-author on the Asara study.
“Consequently no one looked carefully at really old bones.”
That may now change, said Lewis Cantley. He is HMS professor of Systems Biology and BIDMC chief of Signal Transduction. He also took part in the study.
“Basically, this is the breakthrough that says it’s possible to get sequences beyond one million years. At 68 million years, it’s still possible to get sequences.”
In addition to the seven dinosaur sequences, Asara and colleagues isolated and sequenced more than 70 protein fragments from a mastodon. This was 160,000-600,000 years old. That provides further evidence of the staying power of ancient protein.
There are important implications for handling newly discovered fossils, Asara said. Even with really old fossils people should avoid contamination. They should also “ensure that whatever is there gets well preserved because it can be interrogated.”
The scraps of dinosaur protein were obtained from a T Rex fossil femur. This had been discovered by John Horner, of the Museum of the Rockies, and colleagues in 2003. The location was Hell Creek Formation, a barren fossil-rich stretch of land that spans several states.
The scientists faced two challenges. The first was to gather enough protein to sequence. The bone extract was in the form of a gritty brown powder that had to be rid of contaminants. Asara purified the protein – identified as collagen – and broke it down into fragments, 10 to 20 amino acids long. He used techniques developed while working on the mastodon sample.
The peptides were passed over a liquid chromatography (LC) column. This separated them from one another. They were then sprayed at extremely low flow rates, for best sensitivity, into a mass spectrometer.
This measures the mass – specifically the mass-to-charge ratio – of peptides as they come off the LC column. To get the greatest possible yield, Asara used an ion-trap mass spectrometer. This captures and holds peptides.
The collected peptides were measured for mass. In a second step, they were isolated and fragmented to reveal their amino acid sequence. Using this two-step procedure, Asara gained seven separate strings of amino acid.
He now faced his second challenge. This was to make sense of the amino acid sequences. Normally, when a sequence comes out of a mass spectrometer, it is compared to a database of existing amino acid sequences. Collagen is a protein that does not vary much with evolution.
So it was highly likely that some of the dinosaur peptide sequences would match those of an existing species. Of the seven T. rex peptides, five were for a particular class of collagen protein – collagen alpha I. These were found to be matches to amino acid sequences in chicken collagen alpha I.
For extinct species, the real goal is to find sequences unique to that organism. Asara generated a set of theoretical collagen protein sequences. These were some of the kinds that might have been present around the time of T. rex.
None of his dinosaur peptides matched the theoretical set. But this is not surprising. “If you’re only finding seven sequences in T. rex, you’re not going to find novel ones,” said Asara.
He also tested mastodon bone, sent by Schweitzer, against a database of existing amino acid sequences and against mastodon theoretical sequences. He identified a total of 78 peptides, including four that were unique.
The team will get better at doing the extractions, Cantley said. And their instruments and techniques will improve. That means they will be able to get “much more extensive sequences” from ancient fossils. They should also get “novel sequences unique to that species, which will give us ideas about the relationship between species.”
Still, it may be very rare fossils that are as well preserved as the T. rex and mastodon specimens analysed in the current study.
“Nature has to give you the opportunity to do this first,” Asara said.
Links to free teaching resources for this story
Proteins are about half the dry weight of most cells, and are the most complex macromolecules known. Each protein has a unique structure and function. Includes nice amino acids interactive.
Narrated animation of protein synthesis, starting with DNA, which is transcribed into messenger RNA, which leaves the nucleus and binds to a ribosome. Transfer RNAs then attach and build a polypeptide chain that folds into a protein.
Learn how modern scientists can use a tool not available in Darwin’s time: molecular evidence. Molecular biologists have uncovered genetic links between diverse animal species, providing new evidence of common ancestry.
Companion website to the NOVA program Curse of T. Rex, which follows the trail of legal and illegal fossil-dealing as the FBI tries to protect the best Tyrannosaurus rex specimen ever found from winding up on the shelves of a souvenir shop.
When dinosaurs ruled the Earth from Discovery School. Students will understand: The age of the dinosaurs is called the Mesozoic age. It is divided into three periods, the Triassic, the Jurassic and the Cretaceous. Plants and animals on Earth differed during these three periods…
“Building a free-standing mount of a forty-foot skeleton wasn’t easy.”
“The more we learn about dinosaurs the more fascinating they become. But how do we know they really existed? And how do we know so precisely when they lived? The fossilised dinosaur bones and tracks in this still collage produced for Teachers’ Domain offer physical evidence – the foundation of all science – of the dinosaurs’ existence.”
Lesson from a teacher designed to give students a different way of looking at genetics and biotechnology. “After reading the novel “Jurassic Park” by Michael Crichton, I decided to incorporate the ideas of the novel into my genetics unit. Crichton is a graduate of Harvard Medical School and does an exceptional job of blending science and suspense; a perfect blend for any high school science student.”
Dinosaur Detectives from Discovery School. Students will: Understand that discoveries about dinosaurs have a long history and that each palaeontologist adds his or her work to a body of fossil evidence used to support theories about dinosaurs. Find out that palaeontologists often support one theory over another until additional fossil evidence …”
“The study of dinosaurs stretches our imaginations, gives us new perspectives on time and space, and invites us to discover worlds very different from our modern Earth.” Questions and answers from US Geological Survey.
Links to more links
Archaeopteryx, ancient birds, and dinosaur-bird relationships.
Lesson plans and activities for teachers based on DNA series from PBS.
Posted under Biology
9
April
2007
Links to free teaching resources for the forests warming story
Teaching resources (UK US) designed specifically for this story at www.realscience.org.uk
“Is human activity bringing about alarming global warming and related catastrophes? Or is such thinking a myth brought about by flawed or incomplete science?” Detailed lesson and resources from PBS.
“Changes to Earth’s global climate have had and will have major consequences for life on Earth. Using evidence preserved in ice for tens of thousands of years, scientists are searching for an understanding of the history of Earth’s climate changes in order to predict what the future holds for life on the planet. In this lesson, students learn about ways in which we study past climate change, and reflect on the present condition of Earth’s climate.” Detailed lesson and resources from Teachers’ Domain (simple registration required).
“Climate changes have occurred throughout Earth’s history, with dramatic consequences to the organisms that live there. Although some climate changes are a part of Earth’s natural cycles, others are the by-product of human activity… In this lesson, students conduct an experiment to learn about CO2 levels in different gases. Then they reflect on CO2 production on a global scale. They also look at evidence of global warming in our environment, and consider their own role.”
“In the past few years several attempts have been made to assess changes in the Earth’s planetary albedo, and claims of global dimming and more recently brightening have been debated in journal articles and blogs.”
“This site gives students an opportunity to explore storm clouds and climate change through the use of NASA climate research data obtained through satellite imaging. The challenge is to investigate actual scientific research data on clouds and storms, and make the resulting observations and interpretations available to NASA research scientists for review.”
Climate change for kids.
“Inquiry-based classroom activity which explores the impact of climate change and variability on forests… The scenario invites students to examine higher level issues of climate variability and change, by creating a practical, scientifically-sound model to address specific points of a localised situation.”
This applet lets students explore how emissivity, albedo and solar output affect temperature throughout the atmosphere. There are controls for adjusting atmospheric emissivity, planetary albedo, and the solar constant.
The story:
Uncool trees
Planting new trees in certain parts of the planet may warm the Earth, according to a new study.
The research was led by Govindasamy Bala. He is an atmospheric scientist at Lawrence Livermore National Laboratory. It appears in the April 9-13 online edition of the Proceedings of the National Academy of Sciences.
Planting and preserving forests in the tropics, on the other hand, is likely to slow global warming.
The new study looks at the effects of large-scale deforestation on climate and the carbon cycle. It uses an interactive, 3-dimensional, climate-carbon model.
The model showed that more trees in mid-latitudes, like the United States and most of Europe, would create slight benefits. But extra trees in the forests of Canada, Scandinavia and Siberia could make things worse.
Forests affect climate in three different ways. They absorb the greenhouse gas carbon dioxide from the atmosphere. This helps stop the planet from warming. They evaporate water to the atmosphere and increase cloudiness. This helps keep the planet cool too.
But the third effect arises because forests are dark and absorb sunlight. This is called the albedo effect. Unlike the other two this helps warm the Earth.
The new study shows that only tropical forests are strongly helpful in helping slow global warming, Bala said.
It is a win-win situation in the tropics, he added. Trees there absorb carbon dioxide. They also create clouds that cool the planet. “In other locations, the warming from the albedo effect either cancels or exceeds the net cooling from the other two effects.”
Other researchers from the Carnegie Institution, Stanford and Université Montpellier II, France also contributed to the report.
The authors state firmly that cutting down trees outside the tropics should not be seen as a way to lessen climate change.
Preserving ecosystems is one of the main goals of preventing global warming, said Ken Caldeira. He is at the Carnegie Institution and is a co-author of this report. “The destruction of ecosystems to prevent global warming would be a counterproductive and perverse strategy.
“Apart from their role in altering the planet’s climate, forests are valuable in many other aspects,” Bala said.
Forests provide natural habitat to plants and animals. They preserve biodiversity. They produce valuable timber and firewood. They protect watersheds and help prevent oceans turning acid.
Broad goals should be pursued when planning responses to global challenges, Caldeira said. “It is important to avoid narrow criteria that may lead to environmentally harmful consequences.”
Posted under Earth science
9
April
2007
Links to free teaching resources for the magnetar story
Teaching resources (UK US) designed specifically for this story at www.realscience.org.uk
Ask an astrophysicist: questions and answers about neutron stars.
How do stars form and evolve?
Star Count is a NASA education activity that “turns students into astronomers and gives teachers the resources to capitalize on the fun”. It challenges students to research answers to the questions: “Do people everywhere see the same number of stars in the night sky? Why or why not?” The activity encourages students to go outside at night and count the stars in the sky.
Background on the end of stars.
All the stars in the universe are nuclear furnaces fueled by fusion, which creates all the naturally occurring elements heavier than hydrogen and helium. This video segment from NOVA illustrates the critical role that stars play in creating the elements.
“There’s one kind of star that I find fascinating, and that’s neutron stars. These are the densest things … in the universe, and they actually do have solid surfaces, but it’s a solid form of a whole different state of matter than we’ve ever encountered …”
In a lucky observation, scientists say they have discovered a neutron star in the act of changing into a rare class of extremely magnetic objects called magnetars. No such event has been witnessed definitively until now. This discovery marks only the tenth confirmed magnetar ever found…
The discovery early this year of the first magnetar – a highly magnetized star – put the spotlight on a small class of stars called Anomalous X-ray Pulsars, or AXPs.
“Twenty years ago today, a new astrophysical mystery came banging on the door. It was a burst of gamma radiation so strong that it swamped detectors. It was the calling card for a new type of star – the magnetar.
Links to more
NASA online resources on stars
Teaching tools and astronomy basics from Amazing Space.
The story:
Cosmic hiccup
Using data from X-ray satellites, astronomers have caught a magnetar in a giant cosmic hiccup.
When it comes to eerie astrophysical effects, magnetars are hard to beat. The massive remains of exploded stars, magnetars are the size of mountains. But they weigh as much as our sun. This makes them incredibly dense.
Magnetars are a type of neutron star. But they possess magnetic fields hundreds of trillions of times as powerful as Earth’s magnetic field – which turns compass needles north.
The giant cosmic hiccup still has scientists puzzled. The researchers describe it in multiple reports in the Astrophysical Journal and Monthly Notices of the Royal Astronomical Society.
The magnetar is in a star cluster about 15 000 light-years away, in the Ara constellation. This is in the southern hemisphere. The magnetar goes by the official name of CXOU J164710.2-455216. Informally it is known as the Westerlund 1 magnetar.
“We only know of about a dozen magnetars,” says Michael Muno. He is a scientist at the California Institute of Technology’s Space Radiation Laboratory. He is the original discoverer of the magnetar.
“In brief, what we observed was a seismic event on the magnetar, which tells us a lot about the stresses these objects endure.”
In September 2005, about a year after Muno found the magnetar, the object produced a burst of radiation. Luckily this came at a time when it was being observed closely by several satellites. These included the European Space Agency’s X-ray satellite, XMM-Newton, and NASA’s Swift X-ray and gamma-ray observatory.
Just five days before the burst, Muno and his collaborators had been looking at the magnetar with XMM-Newton. They saw it in the relatively calm state in which he had first found it.
As most magnetars do, this one produces a beam of X-rays. These sweep across the heavens once every ten seconds. Earth lies in the path of this beam. So the magnetar’s speed of rotation could be determined very precisely.
The event that produced the burst caused the magnetar to shine 100 times more brightly. It created three separate beams that sweep past Earth where only one had existed before. It sped up its rotation rate by about a thousandth of a second.
Muno says more work is needed to understand what happened. The magnetar is built of matter far denser than anything on Earth. Its composition is a bit of a mystery.
But it is possible to make educated guesses. This can be done by extending theories that explain other neutron stars:
The magnetic fields inside the neutron star are probably wound up, like a twisted spring. As the magnetic fields unwind they create stresses in the outer crust, rather like the stresses created by plate tectonics on Earth.
The crust would resist these stresses for a while. But eventually it would fracture. This would produce a seismic event – a “starquake”. The fractures would cause the magnetar’s surface to shine brightly, from many sources.
In addition, there is reason to think that part of the interior of the neutron star is liquid. This may be rotating faster than the crust. The seismic event could cause this fluid to become attached to the crust. That would make the outer crust speed up slightly. “We think the crust cracked,” Muno says.
The observations are important for two reasons, he adds. “First, we have now seen another way in which these exotic objects dissipate their internal fields as they age.
“Second, this event was only spotted because a team of us were concentrating hard on this newly discovered object. The fact that we saw the event only a year after we discovered the magnetar implies that dozens more could be lurking in our Galaxy.
“If we find many more of these magnetars, we will have to re-evaluate our understanding of what happens when stars die,” says Gianluca Israel. He is an Italian astronomer who is publishing a separate paper on the magnetar with his collaborators in the Astrophysical Journal.
Muno is lead author of a paper appearing this week in Monthly Notices of the Royal Astronomical Society.
Posted under Physics
3
April
2007
3-Apr-2007 “The potential threat from near-Earth asteroids can sometimes seem purely theoretical, an academic exercise in how orbits are calculated and refined. But when we start quantifying possible damage from an asteroid strike, the issue becomes a little more vivid.” From Centauri Dreams.
29 March 2007 Astronomers describe in unprecedented detail the double asteroid Antiope, which is shown to be a pair of rubble-pile chunks of material, of about the same size, whirling around one another in a perpetual pas de deux.
27 March 2007 Received a wonderfully evocative short note today about one of the scientists for whom the YORP effect was named.
From Mary:
“O’Keefe was my father. He was also responsible for discovering that the earth is (slightly) pear shaped, for which reason, we received many lugs of pears for Christmas for several years. He figured out how to map China when going from flat to round was unusual (during WWII) and he figured out that a satellite would help us to map the earth. He said tektites were from the Moon, and when nobody would listen, we put it on his funeral program so he’d have one more chance. He liked Wyeth and always talked about his appreciation of how light looks red when it comes through smoke or fog, but looks blue if it bounces off. I found his earliest comments about this in a letter to my mother before they married; he had read Goethe’s Farbenlehre.
“He believed very strongly that, as a civil servant, he was in the employ of the citizens of the US, who had a claim on his attention. Therefore those who wrote to him always received polite answers, even the little old ladies who wanted him to repent of his belief that the earth is round, or that it circuits the sun.
“He always wanted to be an astronomer; now he has an asteroid and an astral effect named after him. Good.”
26 March 2007 “Asteroid missions are exciting for their daring, their potential for scientific return, their ability to help protect the planet, and their meaning in humankind’s growth into a spacefaring species.” Interesting, readable paper by aerospace engineer.
9 March 2007 YORP effect story and science teaching resources (US or UK English) posted at www.realscience.org.uk
Posted under News updates
