An unmanned NASA spacecraft is about to make its deepest dive ever into the icy spray emanating from the underwater ocean on Saturn's moon, Enceladus.

The tiny moon orbiting the sixth planet from the sun stunned scientists when they discovered it had an icy plume in 2005.

Haze from Indonesian forest fires has spread to the southern Philippines, disrupting air traffic and prompting warnings for residents to wear face masks, authorities said Friday.

The large southern Philippine island of Mindanao is more than 1,200 kilometres (745 miles) from the nearest fires but the haze has become a worsening problem over the past week, aviation authorities said.

A big asteroid is hurtling toward Earth and will shave past our planet on Halloween, but astronomers say there's no need to be spooked -- it's definitely not on a collision course.

Early estimates put its size of the asteroid -- called 2015 TB145 -- at about 1,542 feet (470 meters) in diameter, according to the astronomy website Earth and Sky.

Albert Einstein's general theory of relativity is about to celebrate its 100th anniversary, and his revolutionary hypothesis has withstood the test of time, despite numerous expert attempts to find flaws.

"Einstein changed the way we think about the most basic things, which are space and time. And that opened our eyes to the universe, and how the most interesting things in it work, like black holes," said David Kaiser, professor of the history of science, technology and society at  the Massachusetts Institute of Technology (MIT).

Two vast marine sanctuaries proposed for Antarctica were being considered for a fifth time at international talks Monday with campaigners saying they are imperative to protect one of the world's last untouched wildernesses.

The fate of the plans to shield critical areas of ocean around the frozen continent is in the hands of the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR), which opened its annual meeting in Hobart.

The calendar says it's still spring in Rio de Janeiro, but the coastal Brazilian city is suffering through one of the most severe bouts of hot weather of the past century.

For a second consecutive day on Friday, the mercury hit 43 degrees Celsius (more than 109 degrees Fahrenheit), the third hottest temperature recorded on this date in nearly a hundred years of record-keeping, according to the National Institute of Meteorology (INMET).

U.N. Secretary General Ban Ki-moon is "reasonably optimistic" about a world climate conference due to open in Paris at the end of next month, he said in an interview published Thursday.

"I am still reasonably optimistic that world leaders will be able to adopt a universal protocol on climate change before the end of the year," he told Italy's Corriere della Sera daily.

Pollution in nearly 80 percent of Chinese cities surveyed by Greenpeace "greatly exceeded" national standards over the first nine months of this year, the advocacy group said on Thursday.

The average level of PM2.5 particulates -- small enough to deeply penetrate the lungs -- in the 367 cities tested was also more than four times the maximum recommended by the World Health Organization (WHO), Greenpeace said.

An Australian zoo Wednesday unveiled a baby chimp adopted by a pregnant female in an "unheard of" act after his mother died during birth.

The baby, whose name Boon means blessing, was orphaned when mum Soona died shortly after he was born at Monarto Zoo, southeast of Adelaide, late last week.

A new method to chemically analyze dinosaur egg shells has allowed scientists to gauge the extinct lizards' body temperature, researchers said on Tuesday.

The findings support recent work by other teams that dinosaurs were neither warm- nor cold-blooded, but somewhere in between, researchers wrote in the journal Nature Communications.