Force behind Jupiter's thunderbolts

The mysterious Great Red Spot of Jupiter - a huge anticyclone of bad weather that has been raging on its equator for the past 300 years - may be driven not by the heat of the Sun but by heat generated within the planet itself.

The mysterious Great Red Spot of Jupiter - a huge anticyclone of bad weather that has been raging on its equator for the past 300 years - may be driven not by the heat of the Sun but by heat generated within the planet itself.

A team of astronomers led by Peter Gierasch of Cornell University, in Ithaca, New York, reports in Nature that the two large storms close to the Red Spot are created by conditions similar to the tropical thunderstorms on Earth but may actually result from planetary rather than solar energy.

One possible driving force for these storms is moist convection: the rising of water-rich gases, accompanied by condensation and cloud formation. On Earth this sort of activity, driven by the Sun's heat, causes intense storms in the tropics. However, on Jupiter, which has a thick atmosphere of hydrogen, helium, nitrogen, methane, ammonia and water vapour, about twice as much heat is generated from within the planet as is absorbed from the Sun.

The scientists, using data gathered from the Galileo spacecraft, believe that these Jovian storms strongly resemble scaled-up versions of the thunderstorms on Earth. They lead to opposing eastward and westward jets of wind, which feed the encircling Red Spot, one of the most distinct features of Jupiter when viewed from Earth.

THERE IS more evidence that life may exist in Lake Vostok, the subterranean Antarctic lake that has been cut off from the rest of the world for thousands, if not millions, of years.

The lake remains liquid despite being buried under 4km of ice. It was only discovered in the Seventies by Russian scientists. Martin Siegert of the University of Bristol has now found evidence to suggest that the lake is constantly exchanging water with the ice above it, indicating that the lake's water is being enriched with minerals and sediments trapped in the ice above.

Research published in Nature shows that ice is being lost from the base of the sheet in the north and west of the lake. To the south, however, ice is being formed by the freezing of the lake's water.

Such a circulation pattern suggests a net flow of minerals and other material into the lake from the ice above. That would provide the necessary elements for any lifeforms that may live in the lake.

A piece of pottery, no bigger than a few inches high and representing a bearded figure of a man, has provoked fierce controversy over whether the Ancient Romans managed to travel to the Americas.

The black terracotta figure was found in 1933 about 65km west of Mexico City. Dating now suggests it is 1,800 years old and was buried not later than 1510, a decade before the Spanish discovered the New World. Roman Hristov, an independent anthropologist, is reported in New Scientist as arguing that the statuette is Roman; that historians have clearly identified it as different from other pre-Colombian art and remarkably similar to that of Ancient Rome. Others say that even if it is Roman, the pottery could have been recovered from a Roman shipwreck off the Mexican coast, indicating little or no contact.