Saturday, January 31, 2009

Why are the sun and moon the same size in the sky?

It is one of the most glorious pieces of natural theatre. Assuming you spend your life on the same part of the Earth's surface, you might witness it once - if you are particularly lucky or very long-lived, perhaps twice. But a total solar eclipse is worth the wait. At the height of totality, the fit of sun and moon is so perfect that beads of sunlight can only penetrate to us through the rugged valleys on the lunar surface, creating the stunning "diamond ring" effect.

It is all thanks to a striking coincidence. The sun is about 400 times as wide as the moon, but it is also 400 times further away. The two therefore look the same size in the sky - a unique situation among our solar system's eight planets and 166 known moons. Earth is also the only planet to harbour life. Pure coincidence?

Almost undoubtedly, say most astronomers. But perhaps it is not so much of one as the bare numbers suggest. Our moon is different. The many moons of the large outer planets - Jupiter, Saturn, Uranus and Neptune - are thought to have originated through one of two processes: from the accretion of a disc of material in the planet's gravity field, in a miniature version of the formation of the solar system's planets, or through the later gravitational capture of passing small bodies. The second possibility is also thought to account for Mars's two small satellites, Deimos and Phobos, the only other moons in the inner solar system.

But our moon is simply too big relative to Earth's own size to have formed easily by either of these processes. Planetary scientists believe there can be only one explanation: in the first 100 million years of the solar system, when unattached debris was still zinging around the inner solar system, a Mars-sized object smashed into Earth. That impact radically remodelled our planet, expelling a huge amount of debris that eventually congealed into our oversized moon.

And here's the best bit. Such a big moon is a big boon for life on Earth. As Earth spins on its own axis, it has a natural tendency to wobble, owing to the varying pull on it from other bodies such as the sun. The unseen hand of the moon's gravity gently damps that wobble, preventing rotational instabilities which would otherwise have caused dramatic changes in Earth's climatic zones over time. Such instabilities would have made it much more tricky for life to get started on our planet.

Earth's position in the "habitable zone" around the sun where liquid water is abundant is undoubtedly the single most important factor in its fecundity. But the presence of a large moon - one large enough to cause total eclipses - might also have been crucial. If so, that has important consequences for the search for life on other planets.

Since the impact that created it, the moon has been moving steadily away from us, currently about 3.8 centimetres per year. The dinosaurs did not see eclipses like we do: the moon was too close 200 million years ago, more than big enough in the sky to block out the entire sun. Equally, any occupants of Earth in a couple of hundred million years' time will not see total eclipses at all, as the moon will appear too small.

Our luck seems the result of two coincident timescales: that of the recession of an impact-formed moon, and that for the evolution of intelligent life. If you should be fortunate enough to experience a total eclipse in your lifetime, consider this intriguing possibility: that large moon might be the reason you are there.

Friday, January 30, 2009

Dolphins are capable sea chefs, scientists say

Dolphins are the chefs of the seas, having been seen going through precise and elaborate preparations to rid cuttlefish of ink and bone to produce a soft meal of calamari, Australian scientists say.

A wild female Indo-Pacific bottlenose dolphin was observed going through the same series of complicated steps to prepare cuttlefish prey for eating in the Spencer Gulf, in South Australia state.

"It's a sign of how well their brains are developed. It's a pretty clever way to get pure calamari without all the horrible bits," Mark Norman, the curator of mollusks at Museum Victoria and a research team member, told the Canberra Times newspaper.

The research team, writing in the science journal PLoS One, said they repeatedly observed a female dolphin herding cuttlefish out of algal weed and onto a clear, sandy patch of seafloor.

The dolphin, identified using circular body scars, then pinned the cuttlefish with its snout while standing on its head, before killing it instantly with a rapid downward thrust and "loud click" audible to divers as the hard cuttlebone broke.

The dolphin then lifted the body up and beat it with her nose to drain the toxic black ink that cuttlefish squirt into the water to defend themselves when attacked.

Next the prey was taken back to the seafloor, where the dolphin scraped it along the sand to strip out the cuttlebone, making the cuttlefish soft for eating.

Norman and study co-author Tom Tregenza, from the University of Exeter, said the behavior exhibited between 2003 and 2007 was unlikely to be a rarity.

"In addition to our observations, individual bottlenose dolphins feeding at these cuttlefish spawning grounds have been observed by divers in the area to perform the same behavioral sequence," they said in the study.

"The feeding behavior reported here is specifically adapted to a single prey type and represents impressive behavioral flexibility for a non-primate animal."

A separate 2005 study provided the first sign dolphins may be capable of group learning and using tools, with a mother seen teaching her daughters to break off sea sponges and wear them as protection while scouring the seafloor in Western Australia.

The mammals used the sponges "as a kind of glove" while searching for food, University of Zurich researcher Michael Krutzen told New Scientist magazine.

Other researchers have observed dolphins removing the spines from flathead fish prey and breaking meter-long Golden Trevally fish into smaller pieces for eating.

Thursday, January 29, 2009

Fraunhofer claims world record in solar cell efficiency - 41.1%

Munich (Germany) – Solar cells remains one of the most fascinating and promising research areas these days. Scientists at the German Fraunhofer Institute of Solar Energy Systems (ISE) recently announced that they've developed a solar cell capable of providing 41.1% efficiency, which is the highest level achieved to date. They are now working to make the technology commercially available.

The new solar cell is an evolution in Fraunhofer’s metamorphous solar cell research, which has been in place since 1999. The research is focused on combinations of semiconductor materials, in this case it's GaInP / GaInAs / Ge (Gallium-Indium-Phosphid / Gallium-Indium-Arsenide / Germanium). In 1999, the scientists discovered that these materials are well-suited for converting sunlight into electricity, and today it seems their long effort is paying off.

Over the years, the research group at Fraunhofer has been working on methods to better align the material and its cell structure with spectrum received from sunlight on the surface of our planet. What makes this newly developed solar cell special is that the scientists were able to identify and correct defective areas within the non-electrical crystaline portion of the solar cell, thus creating a much more efficient cell; one that can be created virtually free from defects.

Fraunhofer's new solar cell. At 454x normal sunlight concentration, it achieved 41.1% efficiency.

A 5mm2 solar cell (Ga0.35In0.65P / Ga0.83In0.17As) built with this new material and knowledge was exposed to a concentration of sunlight 454x times normal. It achieved an efficiency of 41.1%, and at 880x normal sunlight intensity, it achieved a 40.4% efficiency. What is even more noteworthy though, is the fact that Fraunhofer is already working with Azur Space and Concentrix Solar to implement their technology into "competitive" commercial products. The researchers did not say how long it will take until the cells are available.

However, we did hear that it is unlikely mainstream consumers will be able to buy this technology and install it at home anytime soon. When available, these will be a fairly expensive solar cells that are likely to be used in large-scale photovoltaic systems as well as solar power plants - at least initially.

Sunday, January 25, 2009

Waste-To-Energy System Could Mean Big Savings

IST Energy Corp. launched a waste-to-energy system into the consumer market that cleanly converts trash into electricity and gas heat.

The GEM3T120 can process up to three tons of paper, plastic, food, wood and agricultural materials daily into pellets. The resulting energy from these pellets is enough to power and heat a 200,000 square foot building housing more than 500 people. With no disposal costs for the waste it processes and the energy produced, IST estimates the GEM creates an annual energy cost savings of about $250,000.

"The GEM is the right product at the right time," said Stu Haber, president and CEO of IST Energy. "The GEM has created a value for every bag of trash we generate - first by eliminating the need for disposal and then by converting it into energy."

"This model can save businesses, institutions and municipalities hundreds of thousands of dollars annually," Haber added. "Never have sustainability and environmental stewardship been more of a focal point for Americans, especially considering President Obama's goals for energy independence."

The GEM can save consumers big bucks, but the benefits of using the system are not only financial. The GEM is eco-friendly and carbon negative, diminishing greenhouse gases by 540 tons annually. In fact, the system powers itself with the clean energy it produces.

Venues that are ideal for the GEM include:

Amusement parks
Arenas and stadiums
Large apartment complexes
Office buildings and industrial plants
City transfer stations

HVAC boot cleared of Asbestos in Los Angeles