‘Biggest observed meteorite impact’ hits the Moon

‘Biggest observed meteorite impact’ hits Moon

 

The impact appeared as a bright white flash on 11 September 2013

Scientists say they have observed a record-breaking impact on the Moon.

Spanish astronomers spotted a meteorite with a mass of about half a tonne crashing into the lunar surface last September.

They say the collision would have generated a flash of light so bright that it would have been visible from Earth.

The event is reported in the Monthly Notices of the Royal Astronomical Society.

“This is the largest, brightest impact we have ever observed on the Moon,” said Prof Jose Madiedo, of the University of Huelva in south-western Spain.

“The impact we detected lasted over eight seconds” – Prof Jose MadiedoUniversity of Huelva

The explosive strike was spotted by the Moon Impacts Detection and Analysis System (Midas) of telescopes in southern Spain on 11 September at 20:07 GMT.

“Usually lunar impacts have a very short duration – just a fraction of a second. But the impact we detected lasted over eight seconds. It was almost as bright as the Pole Star, which makes it the brightest impact event that we have recorded from Earth,” said Prof Madiedo.

The researchers say a lump of rock weighing about 400kg (900lb) and travelling at 61,000km/h (38,000mph) slammed into the surface of the Moon.

They believe the dense mass, which had a width of 0.6-1.4m (2-4.6ft), hit with energy equivalent to about 15 tonnes of TNT.

This is about three times more explosive than another lunar impact spotted by Nasa last March. That space rock weighed about 40kg and was about 0.3-0.4m wide.

Scarred Moon

The team believes the impact has left behind a 40m-wide crater.

“That’s the estimation we have made according to current impact models. We expect that soon Nasa could observe the crater and confirm our prediction,” said Prof Madiedo.

It would be one of many scars on the lunar surface.

Unlike Earth, the Moon has no atmosphere to shield it from meteorite collisions, and its surface shows a record of every strike.

The researchers believe that impacts from rocks of about 1m in diameter could be far more common than was previously thought – both on the Moon and on Earth.

However, most rocks of this size would burn up as they entered the Earth’s atmosphere, appearing as a fireball in the sky.

For meteorites to make more of an impact here, they need to be larger.

For example, the asteroid that exploded over Chelyabinsk in Russia on 15 February 2013 was estimated to be about 19m wide.

It hit the atmosphere with energy estimated to be equivalent to 500,000 tonnes of TNT, sending a shockwave twice around the globe. It caused widespread damage and injured more than 1,000 people.

By Rebecca Morelle

Source: http://www.bbc.co.uk/news/science-envir

The Riverine Rabbit Returns

Cape Town – The critically endangered riverine rabbit – one of South Africa’s 10 most endangered mammals – has taken a short hop away from the precipice of extinction, following the recent discovery of a new population in CapeNature’s Anysberg Nature Reserve near Laingsburg.

It is the first population of the species to have been found in any formal protected area anywhere in the country.

Until now it has been known only on privately owned farmland and private reserves where landowners have been working with conservation authorities and non-government groups to ensure their survival. About two-thirds of its natural habitat has already been destroyed.

The announcement of the discovery was made by “excited” conservation partners CapeNature and the Endangered Wildlife Trust, and followed a search at Anysberg by reserve manager Marius Brand, colleague Corné Claassen, CapeNature’s conservation service manager and reserve staff on the night of December 5.

They captured a young riverine rabbit – proof it is successfully reproducing in this area. After taking genetic samples, the rabbit was released.

Claassen said Brand and some of his staff had previously done a day sweep of the western section of the reserve that has good habitat for the rabbits.

“Two rabbits popped out… but they weren’t 100 percent sure of their identification, so we followed that up with a night drive. We used a vehicle with two spotlights on the back, one on each side, and with six guys on each side of the vehicle and also with spotlights about five to 10m apart. The idea was to flush out anything in the area.”

The drive started at 9pm and just after 11pm the young rabbit was found, and was caught by hand.

They took a small clipping of tissue from its ear and some fur for DNA analysis before letting him go.

“He was just a few kilometres from a private farm where we’ve been aware of a population for the past two or three years. He appeared to have been following the (dry) river course from this farm, so that also opens up a whole lot of other opportunities (to find other riverine rabbits).”

Christy Bragg, manager of the Drylands Conservation Programme of the trust – the organisation has done much work on the rabbit populations known from the Nama Karoo area, said:

“We and CapeNature have been working closely together in the Western Cape to learn more about this iconic Karoo species and it’s wonderful to find these elusive rabbits in new territory.”

l Anysberg, in the Klein Karoo south-east of Laingsburg, is just over 81 000 hectares and was established in 1987 to conserve the local veld type and to eventually reintroduce game species that historically occurred in this region. – Cape Argus

Source: http://www.iol.co.za/scitech/science/environment/return-of-the-riverine-rabbit-1.1625412#.UrcoW_2ZMi4

Carbon Dioxide hits record high

The UN weather agency says concentrations of carbon dioxide pollution in the atmosphere have accelerated and reached a record high in 2012.

The World Meteorological Organisation says carbon dioxide was measured at 393.1 parts per million last year, up 2.2 ppm from the previous year.

Its annual inventory released Wednesday of the chief gases blamed for global warming showed that the 2012 increase in carbon dioxide outpaced the past decade’s average annual increase of 2.02 ppm.

Based on that rate, the WMO says the world’s carbon dioxide pollution level is expected to cross the 400 ppm threshold by 2016 – beyond the 350 ppm that some scientists and environmental groups promote as a safe level.

Source: http://www.timeslive.co.za/scitech/2013/11/06/co2-hits-record-high-un

Unless we change our behaviour now, temperatures will be off the charts, according to experts

Washington – Starting in about a decade, Kingston, Jamaica, will probably be off-the-charts hot – permanently. Other places will soon follow. Singapore in 2028. Mexico City in 2031. Cairo in 2036. Phoenix and Honolulu in 2043.

And eventually the whole world in 2047.

A new study on global warming pinpoints the probable dates for when cities and ecosystems around the world will regularly experience hotter environments the likes of which they have never seen before.

And for dozens of cities, mostly in the tropics, those dates are a generation or less away.

“This paper is both innovative and sobering,” said Oregon State University professor Jane Lubchenco, former head of the National Oceanic and Atmospheric Administration, who was not involved in the study.

To arrive at their projections, the researchers used weather observations, computer models and other data to calculate the point at which every year from then on will be warmer than the hottest year ever recorded over the last 150 years.

Hottest year

For example, the world as a whole had its hottest year on record in 2005. The new study, published on Wednesday in the journal Nature, says that by the year 2047, every year that follows will probably be hotter than that record-setting scorcher.

Eventually, the coldest year in a particular city or region will be hotter than the hottest year in its past.

Study author Camilo Mora and his colleagues said they hope this new way of looking at climate change will spur governments to do something before it is too late.

“Now is the time to act,” said another study co-author, Ryan Longman.

Mora, a biological geographer at the University of Hawaii, and colleagues ran simulations from 39 different computer models and looked at hundreds of thousands of species, maps and data points to ask when places will have “an environment like we had never seen before”.

The 2047 date for the whole world is based on continually increasing emissions of greenhouse gases from the burning of coal, oil and natural gases. If the world manages to reduce its emissions of carbon dioxide and other gases, that would be pushed to as late as 2069, according to Mora.

But for now, Mora said, the world is rushing toward the 2047 date.

Records

“One can think of this year as a kind of threshold into a hot new world from which one never goes back,” said Carnegie Institution climate scientist Chris Field, who was not part of the study. “This is really dramatic.”

Mora forecasts that the unprecedented heat starts in 2020 with Manokwa, Indonesia. Then Kingston, Jamaica. Within the next two decades, 59 cities will be living in what is essentially a new climate, including Singapore, Havana, Kuala Lumpur and Mexico City.

By 2043, 147 cities – more than half of those studied – will have shifted to a hotter temperature regime that is beyond historical records.

The first US cities to feel that would be Honolulu and Phoenix, followed by San Diego and Orlando, Florida in 2046. New York and Washington will get new climates around 2047, with Los Angeles, Detroit, Houston, Chicago, Seattle, Austin and Dallas a bit later.

Mora calculated that the last of the 265 cities to move into their new climate will be Anchorage, Alaska – in 2071. There’s a five-year margin of error on the estimates.

Unlike previous research, the study highlights the tropics more than the polar regions. In the tropics, temperatures don’t vary much, so a small increase can have large effects on ecosystems, he said. A 3° change is not much to polar regions but is dramatic in the tropics, which hold most of the Earth’s biodiversity, he said.

The Mora team found that by one measurement – ocean acidity – Earth has already crossed the threshold into an entirely new regime. That happened in about 2008, with every year since then more acidic than the old record, according to study co-author Abby Frazier.

Of the species studied, coral reefs will be the first stuck in a new climate – around 2030 – and are most vulnerable to climate change, Mora said.

Judith Curry, a Georgia Institute of Technology climate scientist who often clashes with mainstream scientists, said she found Mora’s approach to make more sense than the massive report that came out of the UN-sponsored Intergovernmental Panel on Climate Change last month.

Pennsylvania State University climate scientist Michael Mann said the research “may actually be presenting an overly rosy scenario when it comes to how close we are to passing the threshold for dangerous climate impacts”.

“By some measures, we are already there,” he said.

– AP

 

Source: http://www.news24.com/Green/News/Study-Temperatures-go-off-the-charts-around-2047-20131010

Antarctic ice melting from bottom

Washington – Warming ocean waters are melting the Antarctic ice shelves from the bottom up, researchers said on Thursday in the first comprehensive study of the thick platforms of floating ice.

Scientists have long known that basal melt, the melting of ice shelves from underneath, was taking place and attributed the trend to icebergs breaking off the platforms.

But the new study, to be published in Friday’s issue of the journal Science, said most of the lost mass came from the bottom, not the top.

“Our study shows melting from below by the ocean waters is larger, and this should change our perspective on the evolution of the ice sheet in a warming climate,” said lead author Eric Rignot of Nasa’s Jet Propulsion Laboratory and the University of California, Irvine.

Overall, Antarctic ice shelves lost 1 325 trillion kilograms of ice per year in 2003 to 2008 through basal melt, compared to 1 000 trillion kilograms lost due to iceberg formation.

Freshwater

During the process known as calving, large chunks of ice break off from the part of the ice shelf facing the sea.

The researchers also made the surprising discovery that the three giant ice shelves that make up two thirds of the entire Antarctic ice shelf area only account for 15% of basal melting.

The melted ice shelves are also distributed unevenly across the continent.

Ice shelves tend to lose mass twice as fast as the Antarctic ice sheet on land over the same period, according to the study.

“Ice shelf melt doesn’t necessarily mean an ice shelf is decaying; it can be compensated by the ice flow from the continent,” Rignot said.

“But in a number of places around Antarctica, ice shelves are melting too fast, and a consequence of that is glaciers and the entire continent are changing as well.”

Antarctica holds about 60% of Earth’s freshwater inside its huge ice sheet.

The researchers said that understanding how ice shelves melt will help improve projects of how the Antarctic ice sheet will respond to a warming ocean and raise sea levels.

– AFP

 

Source: http://www.news24.com/Green/News/Antarctic-ice-melting-from-bottom-20130614