A wide-ranging probe into woolly mammoths has added to evidence that the towering tusker was wiped out by climate change, scientists said on Wednesday.

British and Swedish researchers sequenced DNA from 88 samples of mammoth bone, tooth and tusk, looking for a signature in the genetic code that is handed down on the maternal line.

NASA officials say brilliant lights and loud booms reported across the southern U.S. came from a meteor.

Officials at the Marshall Space Flight Center say a fragment of a comet entered Earth's atmosphere Monday night.

Three astronauts returned to Earth Wednesday on board a Russian Soyuz capsule after a half-year mission on the International Space Station (ISS), landing in Kazakhstan, mission control in Moscow announced.

Russians Pavel Vinogradov and Alexander Misurkin landed on schedule at 8:58 am Kazakh time (0258 GMT) in the Kazakh steppe, along with American Chris Cassidy.

A new study of the Monarch butterflies' winter nesting grounds in central Mexico says small-scale logging is worse than previously thought and may be contributing to threats facing the Monarch's singular migration pattern.

The reserve's 33,482-acre (13,550-hectare) core zone lost 41 acres (16.6 hectares) of pine and fir trees so far in 2013, about half of that because of illegal logging, said the study by Omar Vidal, head of Mexico's chapter of the World Wildlife Fund, the WWF, and other authors. The rest of the loss was due to drought or disease-control removal of trees.

Two scientists who illuminated how brain cells communicate, three researchers who developed implants that let deaf people hear and philanthropists Bill and Melinda Gates have won prestigious Lasker Awards for medical research and contributions to public health.

The Albert and Mary Lasker Foundation announced the recipients of the $250,000 prizes on Monday. The awards will be presented Sept. 20 in New York City.

Hong Kong's first battery-powered public bus took to the streets Monday as part of a drive against the city's choking pollution.

Chief executive Leung Chun-ying has pledged to make pollution one of his top priorities during his five-year term, with an official report saying it was the "greatest daily health risk" to the city's residents.

Three simple numbers will prove whether sarin was used to gas Syrians last month: 99-125-81.

Chemists this week around Europe are feeding samples of bodily tissue and dirt collected after chemical attacks in Syria into sophisticated machines. They are waiting for those three numbers to read out in a bar graph on a computer screen. The numbers are sarin's fingerprint, said Carlos Fraga, a chemist who specializes in nerve agent forensics at the Pacific Northwest National Laboratory in the U.S. "You're always going to see that."

Geologists on Thursday announced they had uncovered a stupendous volcano that is the biggest in the world and rivals the greatest in the Solar System.

Dubbed Tamu Massif, the volcano is part of the Shatsky Rise, a deep plateau on the floor of the Pacific located around 1,600 kilometres (1,000 miles) east of Japan, they said.

The giant panda cub born 13 days ago at the National Zoo in Washington is female and she has a live-in dad, the zoo said Thursday.

"We have another girl in our family," said research scientist Jesus Maldonado of the zoo's genetics center as father Tian Tian lounged in the morning sunlight and mother Mei Xiang tended to her newborn in private.

Under the rich Venezuelan soil, paleontologists have found treasures rivaling the bountiful oil: a giant armadillo the size of a Volkswagen, a crocodile bigger than a bus and a saber-toothed tiger.

Oil companies' surveys of the soil have uncovered a trove of fossils dating from 14,000 to 370 million years ago.