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Science news digest – 23rd April 2013

In the science news this week, Kepler telescope discovers “most Earth-like” exoplanets to date, oobleck could make the perfect armour, experts discuss the reintroduction of bears to Scotland, and finally… streetlamps reveal Berlin’s past.

Earth-like planets discovered by Kepler

A further two planets have been confirmed by the space observatory Kepler this week, but these two are particularly intriguing, reported the BBC. Because of their size and distance from their star, both of these planets are predicted to be relatively Earth-like, and could potentially have liquid water on their surfaces.

"They are the best candidates found to date for habitable planets," stated Bill Borucki, who leads the team at NASA responsible for the Kepler telescope.

The two planets, called Kepler-62e and Kepler-62f, are part of a group of five planets orbiting the star, Kepler-62. The star is located in the constellation Lyra and is slightly smaller, cooler and older than our own Sun, but the two Earth-like planets are actually a bit bigger than our planet – about one-and-a-half times the diameter of the Earth.

However, this isn’t large enough to suggest that they would be gaseous bodies, most likely they will be rocky or possibly icy.

The size of the planets isn’t the only thing that makes them such good candidates for life – they are also located in the optimum region around a star known as the “Goldilocks Zone”. This is the distance from a star where is neither too hot nor too cold, meaning that if water was present on the planet surface then it could be in a liquid state.

"Statements about a planet's habitability always depend on assumptions," said Lisa Kaltenegger, a researcher at the Max Planck Institute for Astronomy in Heidelberg.

"Let us assume that the planets Kepler-62e and -62f are indeed rocky, as their radius would indicate. Let us further assume that they have water and their atmospheric composition is similar to that of Earth, dominated by nitrogen, and containing water and carbon dioxide," she said.

"In that case, both planets could have liquid water on their surface: Kepler-62f gets less radiation energy from its host star than the Earth from the Sun and therefore needs more greenhouse gases, for instance more carbon dioxide, than Earth to remain unfrozen.

"Kepler-62e is closer to its star, and needs an increased cloud cover - sufficient to reflect some of the star's radiation - to allow for liquid water on its surface."

Sadly, none of this can be confirmed with current technological abilities, but hopefully as future telescopes improve, planets like these can be investigated further.

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Oobleck could be the armour of the future

It has been the staple of science demonstrations for years – the simple mix of cornflour and water to make what is known as oobleck – used as an example of a non-Newtonian fluid.

Oobleck has a split personality – liquid when under no pressure but solid when under high pressure. This is why you could easily run across a pool of oobleck, but if you hesitated for a moment, you would sink.

Matthieu Roche and colleagues from the University of Paris-South have now been probing the properties of oobleck even further. By spreading a thin layer over a sheet of Perspex, they dropped a 300g tungsten carbide rod onto the oobleck from varying heights and then filmed the results, reported New Scientist.

Roche expected that the oobleck would tear like a soft metal as the weight was dropped on it, a process known as ductile fracture. In fact, the oobleck was shown to shatter, like fracturing glass or plaster, at about 6.7 milliseconds after impact.

Unlike glass though, the cracks sealed up quickly.

The team found that the cracks only appeared when the oobleck layer was below a certain thickness, and that the cracking was actually less dependent on the force of the impact than it was on the thickness of the oobleck layer.

Non-Newtonian fluids are already used in some liquid armours, which are flexible like fabric, but then stiffen to protect against an incoming bullet or knife for example.

The latest results from Roche could go some way in improving the use of non-Newtonian fluids in armours, and also as shock absorbers for cars, for example.

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Debate on whether bears should be reintroduced in Scotland

To mark Earth Day on Monday this week, wildlife experts attended a debate at Lochinver in Sutherland, Scotland to discuss the costs and benefits of reintroducing large animals to the area, reported the BBC.

Historically, bears, wolves and lynxes could all be found in Scotland, and the reintroduction of these animals has been under debate for some time.

A previous programme to introduce four wolves to the Alladale Estate in Sutherland was dropped in May 2010, because there were concerns about the animals’ welfare.

The general manager, Hugh Fullerton-Smith, explained at the time that it was still the long-term ambition of the estate to introduce wolves but into a much larger area.

"We studied very carefully small enclosures throughout Britain and, to be frank, we weren't comfortable about bringing them into very small enclosures on welfare grounds," he said.

However, the welfare of the animals is not the only concern that has been raised by experts. In 2010, Ray Mears warned that the reintroduction of wolves to Scotland could lead to drastic changes in the natural habitat.

"If someone was saying we are releasing them because we think it will create an eco-system that was more harmonious and because their absence was felt in the landscape then I would agree with it,” he explained.

"If we were releasing them because we want to see them, I don't think that is a good enough reason."

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And finally…

ISS image reveals Berlin’s segregated history

It may have been 20 years since the Berlin Wall fell, but the city’s past is still plain to see in other ways. A photo from Chris Hadfield, the Canadian astronaut currently residing on the International Space Station, shows the German capital at night, and the split between East and West because of the different light bulbs used by both, reported the Guardian.

Berlin at night - Image credit: NASA

"Berlin was divided into two parts for over 40 years," explains Christa Mientus-Schirmer of Berlin's city government. "And although we've made a lot of progress in the 20 years since the wall fell, we haven't had the money we would have liked to equalise the two parts of the city."

Daniela Augenstine, of the city's street furniture department, says: "In the eastern part there are sodium-vapour lamps with a yellower colour. And in the western parts there are fluorescent lamps – mercury arc lamps and gas lamps – which all produce a whiter colour."

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