Coldest spot on Earth identified by satellite


High Plateau
Antarctica‘s dry and clear conditions allow heat to be radiated very efficiently out into space

The coldest place on Earth has been measured by satellite to be a bitter minus 93.2 Celsius (-135.8F).

As one might expect, it is in the heart of Antarctica, and was recorded on 10 August, 2010.

Researchers say it is a preliminary figure, and as they refine data from various space-borne thermal sensors it is quite likely they will determine an even colder figure by a degree or so.

The previous record low of minus 89.2C was also measured in Antarctica.

This occurred at the Russian Vostok base on 21 July, 1983.

It should be stated this was an air temperature taken a couple of metres above the surface, and the satellite figure is the “skin” temperature of the ice surface itself. But the corresponding air temperature would almost certainly beat the Vostok mark.

“These very low temperatures are hard to imagine, I know,” said Ted Scambos from the US National Snow and Ice Data Center in Boulder, Colorado.

“The way I like to put it is that it’s almost as cold below freezing as boiling water is above freezing. The new low is a good 50 degrees colder than temperatures in Alaska or Siberia, and about 30 degrees colder than the summit of Greenland.

“It makes the cold snap being experienced in some places in North America right now seem very tame by comparison,” he told BBC News.

Dr Scambos was speaking here in San Francisco at the American Geophysical Union (AGU) Fall Meeting, the largest annual gathering of Earth scientists.

AntarcticThe 2010 cold spot (red) was just south of a ridge running between Dome A and Dome F

He and colleagues have been examining the data records from polar orbiting satellites stretching back some 30 years.

They find the coldest moments in Antarctica occur in the dark winter months at high elevations, where the extremely dry and clear air allows heat to be radiated very efficiently out into space.

It is evident that many super-cold spots are “strung out like pearls” along the ridges that link the high points, or domes, in the interior of the continent.

They are not quite at the ridge crests, but set slightly back down the slope.

“Air chilled near the surface flows downhill because it’s denser; and it flows into these very shallow topographic pockets,” explained Dr Scambos.

“If you were standing in one of these places, you’d hardly notice you were in a topographic low – it’s that gentle and that shallow. But it’s enough to trap this air.

“And once in those pockets, the air can cool still further and get down this extra three or four degrees below the previous record air temperature in Vostok.”

The cold pockets run in a line for hundreds of kilometres between Dome Argus [Dome A] and Dome Fuji [Dome F]. They all achieve more or less the same low temperature between minus 92C and minus 94C. The minus 93.2C figure is the temperature event in which the team has most confidence. It was recorded at a latitude of 81.8 degrees South and a longitude of 59.3 degrees East, at an elevation of about 3,900m.

Hottest place

One of the spacecraft instruments being used in the study is the Thermal Infrared Sensor on the recently launched Landsat-8.

It has very high resolution, but because it is so new the team says more time is needed to fully calibrate and understand its data.

“I’d caution Guinness not to take this result and put it in their world record book just yet, because I think the numbers will probably adjust over the coming year,” Dr Scambos told BBC News. “However, I’m now confident we know where the coldest places on Earth are, and why they are there.”

By way of comparison, the hottest recorded spot on Earth – again by satellite sensor – is the Dasht-e Lut salt desert in southeast Iran, where it reached 70.7C in 2005.

The coldest place in the Solar System will likely be in some dark crater on a planetary body with no appreciable atmosphere. On Earth’s Moon, temperatures of minus 238C have been detected.

BBC Weather presenter Peter Gibbs explains how he found life living in Antarctica for two years

 

Chinese Astronomers Search for Alien Life.


china alien

Chinese astronomers, actively searching for Earth-like planets using survey instruments in Antarctica, believe efforts to seek an extra-solar planet that that harbors life will soon be rewarded. “It’s highly possible that human beings might find such a planet in the coming few years,” said Lifan Wang, an astronomer at Texas A&M University in College Station, and director of the Chinese Centre for Antarctic Astronomy in Nanjing. “Such planets likely exist in the Milky Way, with a possible distance of thousands of light years from us. We know too little about life. Maybe there are new forms of life that do not need exactly the same environment as we have on Earth. Some can survive in very harsh environments,” Wang added.

Chinese astronomers installed the first of three Antarctic Survey Telescopes (AST3-1) at Dome Argus, located at the highest elevation on the Antarctic continent, at the beginning of 2012. One of its primary missions is to search for extra-solar planets suitable for life.

Dome A may be the best place on Earth to gaze at the Universe, says Wang. At 4,093 meters above sea level, Dome A has an extremely thin and stable atmosphere, and the pressure is only half that at sea level. The extreme cold — temperatures can drop to –80 °C — makes the air very dry and reduces background radiation when observing in the infrared. There is almost no air pollution and the long winter nights allow for four months of uninterrupted observation.

“Antarctica has the best conditions on Earth for astronomical observation, as it has very flat ground, a transparent atmosphere and little turbulence. The ground-based telescopes here will bring us precious information from the universe,” he said. “We will send people there to retrieve observation data. I hope we can find some likely candidates. It’s hard to say precisely how many, but I hope there are no less than 10,” Wang said. “So far, humans have yet to find an exact twin of the Earth.”

“We search through a wide range of main sequence stars, mainly sun-like stars, and then look for planets within a suitable distance around them. Stars that are smaller and darker than the sun, such as dwarfs, are also in our survey scope,” he said.”If the stars are particularly large, they are inclined to evolve faster. Some will explode soon, and their planets will go missing after the explosion.”

The second AST3 will be installed in Antarctica between late 2013 and early 2014, while the third one will be installed between late 2014 and early 2015. “These telescopes are expected to help us find at least 100 sun-like stars. We will work with Australian scientists to further study the movement of the stars to calculate their size,” Wang said.

Chinese scientists are also planning to set up an Antarctic observatory to further boost their research and broaden the search for habitable planets. If approved and included in the 12th Five-Year Plan, the observatory should go into operation by 2020.

Soure: http://www.dailygalaxy.com