On the horizon

Supergiant stars identified

A trio of supergiants - red, cool, bright stars at the end of their lives - may be the biggest stars ever identified, astronomers reported.

All three have diameters of more than 1 billion miles, or 1,500 times the sun's diameter. If they were in the same location as the sun, they would completely engulf Earth and their outer layers would extend to a point between the orbits of Jupiter and Saturn.

The big three - KW Sagitarii, V354 Cephei, and KY Cygni - are slightly bigger than the previous champion, known as Herschel's "Garnet Star," the team of scientists said in research presented at the annual meeting of the American Astronomical Society in San Diego.

Farms: big wasters of water

Growing population coupled with diminishing freshwater supplies should force major changes in the way the world's farmers water their crops in the coming decades, a study recommended.

Since agriculture uses about 70 percent of the world's fresh water every year, farming should be the focus of intense conservation efforts, said David Pimentel, a professor at Cornell University and primary author of the study, published in the October issue of the journal BioScience.

The issue is key because the share of Earth's land area stricken by serious drought has more than doubled, according to a separate analysis by scientists at the National Center for Atmospheric Research in the United States. Widespread drought occurred over much of Europe and Asia, Canada, western and southern Africa, and eastern Australia. Rising global temperatures appear to be a major factor, said Aiguo Dai, the study's lead author.

Dr. Dai and his colleagues found that the fraction of global land experiencing very dry conditions (defined as -3 or less on the Palmer Drought Severity Index) rose from about 10 to 15 percent in the early 1970s to about 30 percent by 2002.

Rats can tell languages apart

The ability to recognize patterns in the sound of speech is considered fundamental to the development of spoken language. Only two species of mammals, humans and tamarin monkeys, were known to possess this ability - until now. New research has identified a surprising third - rats.

Juan Toro and colleagues at Barcelona's Scientific Park in Spain tested 64 adult male rats. They concentrated on Dutch and Japanese because these languages were used in earlier, similar tests, and because they are very different from each other in use of words, rhythm, and structure.

The rats were trained to respond to either Dutch or Japanese using food as a reward. Rats rewarded for responding to Japanese did not respond to Dutch and rats trained to recognize Dutch did not respond to spoken Japanese.

The rats, however, could not tell apart Japanese or Dutch played backwards.

Tsunami threatens turtle species

Endangered sea turtles were also casualties of last month's tsunami, with the monster waves possibly hastening their extinction, a marine expert said.

At least 24 turtles swept up by the waves have been found on the shores of Phuket island, some dead, others with cuts, scrapes and broken shells.

The titanic wave also swept away about two dozen endangered olive ridley turtles that were part of a breeding program which had been increasing their numbers.

"In the worst-case scenario, the effect of the tsunami could make some species of sea turtles extinct," said Kongkiat Kittiwattanawong, a marine biologist at Phuket Marine Biological Center in Thailand.

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