China has showcased its new J-20 stealth fighter in southern Guangdong Province's city of Zhuhai in a spectacular fly over at Air Show China, the country's biggest meeting of aircraft makers and buyers.

Two J-20s, China's fifth-generation jets, swept over hundreds of spectators at the show's opening ceremony in a 60-second flyby on Tuesday. The J-20 is a long-range radar-evading fighter jet equipped with air-to-air missiles. China has reportedly already produced six prototypes of the new stealth fighter, which is expected to add greatly to China's offensive and defensive capabilities.

The J-20, manufactured by Chengdu Aircraft Industries Corporation, is an original Chinese project. China carried out the first test flight of the J-20 back in 2011, but it made its public debut at today's airshow. It is expected to be deployed with the Chinese Air Force within the next two to three years.

Scientists are planning to wipe out a host of dangerous diseases by unleashing millions of genetically modified mosquitoes into the wild so they will have sex with their deadly cousins. And then kill them.

The mosquito species Aedes aegypti carries a number of viruses and diseases, including dengue fever, chikungunya, Zika and yellow fever.

Now scientists in Brazil are preparing to release mutant bugs that will mate with female mosquitos and spawn babies with a genetic flaw that causes them to die off quickly.

British biotech firm Oxitec is behind the genetically modified (GM) insects, that will be produced in a factory before being released into the wild.

A large chunk of space rock is coming dangerously close to the vicinity of the Earth, but scientists are sure it won't collide with our planet, thanks to a new NASA tool designed to detect potentially hazardous space fly-bys.

The incoming rock was detected by the NASA-funded Panoramic Survey Telescope & Rapid Response System (Pan-STARRS) on Maui, Hawaii, on October 26. A new early-warning system, named Scout, promptly analyzed the data on the rock and concluded that the object went in the direction of Earth, but would miss it by about 500,000km (310,000 miles).

"The NASA surveys are finding something like at least five asteroids every night," NASA Jet Propulsion Lab astronomer Paul Chodas said.

How many sperm do you have and how well do they swim? That's been the gold standard forever. Unfortunately, that's a very unsophisticated view of a very complex problem.

That's how Dr. Richard Scott, a fertility specialist in New Jersey, describes the current state of fertility tests for men.

Historically, the blame for a couple's inability to conceive was placed primarily on the mother. Today, we know that in as many as 40 percent of the time the man is the sole cause or a contributing cause of a couple's inability to conceive naturally. Yet this hasn't translated into any improvements in technologies that help men understand their infertility issues. For example, fertility in the United States is a massive industry pulling in $4.5 billion annually, but almost all of the diagnostic tests and treatments are intended for women. As Scott points out, all modern medicine can do for men with potential fertility issues is evaluate his sperm for number and motility. However, sometimes even when both factors are normal, a man's sperm can still struggle to get the job done.

Astronomers have identified an increasing number of asteroids which "pose a threat" to Earth, according to the European Space Agency.

Near-Earth Objects, or NEOs, are asteroids or comets whose orbits are close to ours, meaning there is a risk they could hit Earth.

Ranging in size from meters to tens of kilometres, astronomers are discovering more and more asteroids that could threaten our planet. Since 2010, an additional 5,000 have been discovered, bringing the total known number of NEOs to 15,000.


"The rate of discovery has been high in the past few years, and teams worldwide have been discovering on average 30 new ones per week," Ettore Perozzi of the ESA's NEO Coordination Centre in Italy said in a statement.

"A few decades back, 30 were found in a typical year, so international efforts are starting to pay off. We believe that 90% of objects larger than 1000 m have been discovered, but - even with the recent milestone - we've only found just 10% of the 100 m NEOs and less than 1% of the 40 m ones."

An enormous dome has been discovered growing in the Central Andes above the world's largest active magma store.

Found in the Altiplano-Puna Plateau - the second highest plateau on the planet - the dome stretches more than a kilometre high (3,280 feet), making it 172 metres taller than the world's tallest building in Dubai. Researchers say this massive structure is the result of an injection of magma from below.

"The dome is the Earth's response to having this huge low-density magma chamber pumped into the crust," says one of the team, Noah Finnegan from the University of California, Santa Cruz.

How did we all miss a massive dome of Earth rising a kilometre above the surface?

It just so happens to be hidden within the Altiplano-Puna Plateau - a high, dry region, littered with volcanoes, that extends for some 2,000 km along the Central Andes, with an average height of 4,000 metres.

The Central Andes constitutes an even larger plateau, encompassing southern Ecuador, northwestern Bolivia, and most of Peru. Together, the Central Andes, Southern Andes, and Patagonia make up the Andes, the longest continental mountain range in the world.

The common swift is able to fly continuously for 10 months, without touching down for even a second, according to an extraordinary study which finds the species can stay in the air far longer than any other bird.

Researchers tagged 13 common swifts and followed their every move for two years. They found that while swifts land for two months during the breeding season, it is incredibly rare for them to roost during the rest of the year, when they are migrating between Europe and Africa.

Three didn't alight

In three cases, the bird didn't land on the ground, a tree, water, or anything else for the whole 10 months, while none of the 13 common swifts in the study spent more than 0.5 per cent of their time out of the air.

Researchers have identified the cause of chronic, and currently untreatable, pain in those with amputations and severe nerve damage, as well as a potential treatment which relies on engineering instead of drugs.

Researchers have discovered that a 'reorganisation' of the wiring of the brain is the underlying cause of phantom limb pain, which occurs in the vast majority of individuals who have had limbs amputated, and a potential method of treating it which uses artificial intelligence techniques.

Several newly discovered objects on the outskirts of the solar system suggest that something strange is afoot. While some scientists point to the odd behavior of the newfound residents as further proof for the existence of the hypothetical Planet Nine (a yet-unseen super Earth proposed to inhabit the outskirts) not everyone is convinced.

The new inhabitants include a small icy world with one of the longest known orbits and several smaller objects clustered together extremely far from the sun.

The newest of these objects is L91, an icy world that can travel as far from the sun as 1430 astronomical units (AU), or 1,430 times the Earth-sun distance, one of the longest known orbital periods. L91 never draws closer to the sun than 50 AUs, farther away than even Pluto.

And L91's distant path is shifting.

"It's orbit is changing in quite a remarkable way," astrophysicist Michele Bannister told scientists last week at the American Astronomical Society's Division for Planetary Sciences in Pasadena, California. Bannister, an astrophysicist at Queen's University Belfast, identified minute changes in the object's orbit that could come from the passing gravity of other stars or interactions with the hypothetical Planet Nine. Simulations by the team suggest that the tiny tugs are more likely to come from beyond the solar system, whether distant stars or galactic winds.

Konstantin Batygin, an astronomer at the California Institute of Technology, said, "I think it's a story that's not implausible, but I also think it's not needed." Batygin, who announced the existence of Planet Nine last January, thinks the unusual orbits of L91 and other newfound objects are more likely explained by the hypothetical planet.

Bannister and her team spotted L91 using the Outer Solar System Origins Survey, a 4-year survey hunting distant moving objects using the Canada-France-Hawaii Telescope. L91's mass and size remains unknown.

"It's right at the limit of what we could actually detect in the sky," Bannister said.

The increased risk of stroke that comes with smoking may extend to nonsmokers who live in the same household and breathe in secondhand smoke, a U.S. study suggests. Researchers found that never-smokers who had a stroke were nearly 50 percent more likely to be exposed to second hand smoke at home than people who had never had a stroke.


During the study, stroke survivors exposed to second hand smoke were also more likely to die from any cause compared to those without second hand smoke exposure.

"Second-hand smoke is a risk to all people, but those with a history of stroke should take extra care to avoid it," said lead author Dr. Michelle Lin of the Johns Hopkins School of Medicine in Baltimore. One in four nonsmokers (58 million people) in the U.S. are still exposed to secondhand smoke, according to the Centers for Disease Control and Prevention.


"While cigarette smoking has long been known to increase the risk of stroke, less is known about the relationship between secondhand smoke and stroke," Lin said by email.