Monster storm on Saturn reveals water and hidden layers

A massive storm rages on Saturn once every 30 years, which mixes up the atmosphere and reveals some of its hidden secrets. The most recent mega-storm arrived on the ringed planet about 10 years ahead of schedule, from December 2010 to August 2011, said Lawrence Sromovsky, a planetary scientist at the University of Wisconsin-Madison.

The storm grew quickly from a small white dot first detected by NASA's Cassini probe on Dec. 5, 2010, to a spot about the size of Earth by the end of the month, writes Deborah Netburn for the Los Angeles Times. By the end of January 2011, the storm had totally encircled the planet at a latitude of 30 degrees. The mega-storm raged on for seven more months, releasing static electric charges indicative of lightning and causing fierce vertical winds that blew up to 300 mph.

The storm also allowed scientists a rare opportunity to glimpse the hidden layers of Saturn's thick atmosphere. Scientists have hypothesized that Saturn's atmosphere is stacked like a layer cake, with water vapor clouds at the bottom, followed by a layer of ammonia hydrosulfide clouds and pure ammonia clouds near the top. But this structure has been difficult to observe because the surface of Saturn is obscured by a thick haze that is difficult to penetrate.

The storm temporarily changed all that. As the storm's fierce winds cut through the haze, Cassini was able to observe the cloud tops in near-infrared light, revealing a very different infrared color signature than the one produced by haze particles in the surrounding atmosphere. Sromovsky and his team recently analyzed that data and discovered that cloud particles at the top of the storm were probably made of water ice, ammonia ice and a third substance that might be ammonium sulfide. This is the first time that water ice has been detected on Saturn.

To know more about the research and other details, click here.

Did a meteor kill megafauna and trigger prehistoric climate shift?

Scientists have discovered new evidence that an extraplanetary body came down over Canada around 12,900 years ago, possibly triggering the death of the giant animals then roaming the North American continent, and starting a cooling spell that helped drive mankind towards agriculture and civilization.

During the Younger Dryas climactic period, which kicked off around 13,000 years ago, world temperatures fell sharply, with parts of the northern hemisphere dropping around five degrees Centigrade in a decade or less. The effects lasted for over a thousand years before temperatures warmed up again.

The Younger Dryas has been cited as a reason why North America lost the unique megafauna that roamed the continent, including huge saber-toothed cats, a giant sloth, and colossal camels. The cold period is also thought to have spurred the shift from hunter-gathering to agriculture as the means of production for humanity.

The prevailing theory as to what caused the Younger Dryas is that the climate was altered by the draining of Lake Agassiz, a vast fresh-water lake the size of the Black Sea that was dammed by glaciers in the center of the North American continent. When this vented, it sent an enormous amount for fresh water into the Atlantic and Arctic seas, which could have disrupted warming sea currents.

But an alternative theory suggests that the continent may have undergone a series of bombardments from asteroids or comets, triggering the cooling period. One 4km-wide crater from around that time, the Corossal crater, has already been spotted in Canada.

Professor Mukul Sharma, from Dartmouth University said his team has found direct evidence of another massive impact. Sharma studied core samples from six different sites along the Eastern seaboard, looking for spherules, which are crystalline rocks formed by temperatures of 2,000°C. These can only be formed naturally by volcanoes or impacts – forest or coal fires don't burn hot enough – and Shama's team found concentrations of these indicating that an impact had occurred in Quebec at around the time the Younger Dryas started.

The composition of the spherules differs from the element concentration that would have come from the Corossal crater. Sharma says the team now needs to find another crater to account for the new data, and are looking for a suitable target, according to the paper published in the Proceedings of the National Academy of Sciences.

How did scientists find conclusive proof that the impact caused humans to develop agriculture? Read more from this link.