Earlier estimates had set that figure at about 16 hours and 6 minutes. But, in a paper in Icarus1, Erich Karkoschka, a planetary scientist at the University of Arizona in Tucson, now pegs it at 15 hours, 57 minutes and 59 seconds.
Determining the day length of rocky bodies such as Mars or Mercury is easy, because scientists can look at their surfaces, in photos or radar images, and track the motion of easily identifiable features.
But Neptune is made mostly of thick clouds of gas, so it has no visible surface. The only visible features are storms, the apparent motion of which results from a mixture of the planet's rotation and shifting weather fronts. Until now, the best estimate of the planet's day length came from radio signals measured during a 1989 flyby by the NASA spacecraft Voyager 2. But studies of Saturn have since indicated that such signals are not as clearly tied to the planet's rotation as was once thought.
Karkoschka went back to basics. Poring over archived images from the Hubble Space Telescope, he found that Neptune has two cloud disturbances, dubbed the South Polar Feature and the South Polar Wave, that seem to be linked to surface features deep beneath the clouds, probably a hot spot on the planet's solid core. "The best analogue is clouds moving over a mountain," says Karkoschka. "Each cloud moves, so if you track them you don't get the rotation. But the feature as a whole remains stable."
By painstakingly plotting the positions of the two features in 500 images taken by the Hubble Space Telescope over the course of two decades, Karkoschka was able to pin down the planet's day length to an accuracy of 0.0002 of an hour. To put this into perspective, even with the Cassini probe in orbit around Saturn, the planet's day length is known only with an order of magnitude less certainty, he says.
Knowing a planet's rotation rate to such high precision isn't just interesting information — it has practical applications, too. "It constrains models of Neptune's interior," says Karkoschka. "If you know how fast the planet rotates, you can determine the mass distribution inside."
Neptune still holds many mysteries. In fact, Karkoschka's finding itself raises a new one: the source of the heat that produces the recurring cloud disturbances. Another, says Sushil Atreya, a planetary scientist at the University of Michigan, Ann Arbor, is the source of Neptune's magnetic field.
Such fields on Jupiter and Saturn are believed to result from the movement of metallic hydrogen, produced inside the gassy planets at pressures of several million times that of Earth's atmosphere. But Neptune is smaller than Jupiter or Saturn, with lower internal pressures. "Metallic-hydrogen formation in Neptune is unlikely," says Atreya. There is also the question of why Neptune exists at all.
The planet is 30 times further from the Sun than is Earth. That far out, planet-formation models suggest that the solar nebula, from which planets condensed during the formation of the Solar System, should have been very diffuse, says Francis Nimmo, a planetary scientist at the University of California, Santa Cruz. So scientists believe that Neptune formed closer to the Sun, where the nebula was denser, then moved outwards. But many Neptune-mass planets in other planetary systems seem to have migrated inwards, rather than outwards, says Nimmo. Atreya says that understanding these "hot Neptunes" elsewhere in the Universe requires a better understanding of why our own large planets have ended up so far from the Sun.
"The mystery of Neptune transfers to hundreds of exoplanets that superficially seem similar to Neptune," says Geoffrey Marcy, an astronomer at the University of California, Berkeley, who hunts for planets outside the Solar System. Atreya adds that the solution to these mysteries will be best obtained by sending entry probes and orbiters to Neptune at some point in the future preferably before the planet makes another full orbit of the Sun.
Anti mine campaigners in Uganda have told of their shock to find an unexploded bomb was being used as a school bell.
Workers with the Anti-Mine Network Rwenzori found teachers at a primary school in Kasese district using the mine as a bell.
They were banging it with a rock to call the 700 children at the school to classes or assembly, reports the Daily Monitor.
Wilson Bwambale, co-ordinator of the Anti-Mine Network Rwenzori, said teachers used the bomb in his presence to call students to order.
"It was a shock to us to find out that what the school was using as a bell was a bomb," he said.
"Its head was still active, which means that if it is hit by a stronger force, it would explode instantly and cause untold destruction in the area.
"But we withdrew it to a cordoned place, where it will soon be exploded."
It was the second bomb found in a Ugandan school within six months. Teachers at a different school found students using an unexploded bomb as a toy earlier this year.
Uganda was ravaged by a massive civil war 20 years ago, with fighting between 1996 and 2002. Numerous bombs are believed to still be strewn throughout the region.
An amateur photographer has told how he managed to get this amazing picture of a cat balancing on a 17th floor balcony railing.
Ivo Berg, 22, a marketing engineer from Berlin, was visiting a friend who lived with his two pet cats in a high rise in Santiago, Chile.
He said: "As soon as I got to my friend's apartment I fell in love with the view but I was also very worried about the suicidal behaviour of his two cats.
"They would chase each other through the apartment, fighting and playing. But they would also jump on to the balcony and the railing.
"I was afraid that they could fall, but my friend told me that he tried stopping them from doing it several times, but that they wouldn't.
"It was incredibly frightening and I knew I needed to get a photograph of it, but the problem with cats is they never do what you want them to do.
"When I tried taking a photo they would sit on the railing until I had my equipment ready, then they would jump down and look at what I was doing.
"It was if they were intentionally trying to provoke me. Finally, it was my last evening in Chile and I was determined to get a photo.
"So I waited at the balcony for about 20 minutes, with my camera handy, for the cats to start playing.
"They didn't play, but Cereal jumped on the railing and sat there looking at me.
"I knew this was my chance - the background looked beautiful and I shot about 10 photos before she jumped down."
"Children tease me and my wife doesn't like it, but she must bear all the hardships I have to bear," Singh said, according to The Mirror. "I have no son, so I will never wash again." "They do not understand my decision but I will not change my mind as it is God's choice, not mind," he added.
Singh's wife, 60-year-old Kalavati Devi, said that she cried when her husband explained his plan not to wash, but has since become used to the smell. "I even threatened to stop sleeping with him, but he is my husband so there was little I could do about it," she explained. "He says he'd rather die than take a bath."– It is not an achievement that can readily be savoured by his nearest and dearest.
But Kailash Singh has as good a claim as any to the accolade of world's smelliest man - after refusing to wash for more than 37 years.
Mr Singh, 65, has not bathed or cut his 6ft-long dreadlocks since 1974, shortly after he married.
Explaining his unconventional decision, Mr Singh claimed a priest guaranteed him a much-prized son and heir if he followed the advice.
Despite neighbours joking the sweaty farmer would be lucky persuade his wife to have any children at all, his religious guidance clearly failed - he has seven daughters.
Mr Singh spends his days tending cows in 47C heat, yet the only 'cleansing' he does allow himself is a 'fire bath' each evening, which involves smoking marijuana, praying to the Hindu Lord Shiva and dancing around a bonfire.
His long-suffering family admit they did once tried to force him into a stream.
'He fought us off and ran away,' said wife Kalavati Devi, 60. 'We've tried several times since to force him to have a shower but he puts up such a fuss.
'He says he'd rather die than take a bath and only a son could change his mind. It has been so many years now I've got used to it.'
His wife even threatened to stop sleeping with him if he didn't bath, but she gave in first, insisting she should be loyal and put up with the stench.
The father-of-seven spends all day working up a sweat tending cows and working in his fields near the Indian holy city of Varanasi, on the banks of the River Ganges, where temperatures regularly top 47C.
He admits neighbours in the rural village of Chatav make fun of him but said he is following god's will.
'Children tease and shout that I don't wash when I ride my bicycle through the village,' he said. 'There are many people who have a poor character that mock me for not washing. They do not understand my decision but I will not change my mind as it is god's choice, not mine.
It is not an achievement that can readily be savoured by his nearest and dearest.
But Kailash Singh has as good a claim as any to the accolade of world's smelliest man - after refusing to wash for more than 37 years.
Mr Singh, 65, has not bathed or cut his 6ft-long dreadlocks since 1974, shortly after he married.
Explaining his unconventional decision, Mr Singh claimed a priest guaranteed him a much-prized son and heir if he followed the advice.
Despite neighbours joking the sweaty farmer would be lucky persuade his wife to have any children at all, his religious guidance clearly failed - he has seven daughters.
Mr Singh spends his days tending cows in 47C heat, yet the only 'cleansing' he does allow himself is a 'fire bath' each evening, which involves smoking marijuana, praying to the Hindu Lord Shiva and dancing around a bonfire.
His long-suffering family admit they did once tried to force him into a stream.
'He fought us off and ran away,' said wife Kalavati Devi, 60. 'We've tried several times since to force him to have a shower but he puts up such a fuss.
'He says he'd rather die than take a bath and only a son could change his mind. It has been so many years now I've got used to it.'
His wife even threatened to stop sleeping with him if he didn't bath, but she gave in first, insisting she should be loyal and put up with the stench.
The father-of-seven spends all day working up a sweat tending cows and working in his fields near the Indian holy city of Varanasi, on the banks of the River Ganges, where temperatures regularly top 47C.
He admits neighbours in the rural village of Chatav make fun of him but said he is following god's will.
'Children tease and shout that I don't wash when I ride my bicycle through the village,' he said. 'There are many people who have a poor character that mock me for not washing. They do not understand my decision but I will not change my mind as it is god's choice, not mine.
'My wife doesn't like it either but she must bear all the hardships I have to bear. Besides, I take a fire bath in the evenings and that gets rid of all the sweat.'
Mr Singh's wife claims she has tried everything to make her smelly husband clean up his act without success.
'I abused him and started crying when he told me about his senseless decision,' she said. 'I even threatened to stop sleeping with him but he is my husband so there was little I could do about it.'
Youngest daughter Pooja, 16, even says her father's strange decision has made her more popular.
'My schoolmates are curious to see and meet my papa,' she said. 'They keep asking me how he can live for so many years without washing and want to see for themselves.
'Earlier I would be angry but there's nothing we can do as he doesn't listen to anyone.
'In this hot summer I want to shower at least twice a day but he doesn't want to take even one. I don't know how he manages to live.'
The only contact with water Kailash has is to wash his mouth and hands.
'I have no son, so I will never wash again,' he said. 'Maybe when I am born again I will wash.'
More than 900 sax enthusiasts gathered at Sydney's Cockle Bay wharf Saturday to belt out Waltzing Matilda and Happy Birthday, in celebration of the opening of the Darling Harbour Jazz and Blues Festival.
According to James Valentine of Australian public broadcaster ABC, a record 940 musicians performed. The old record was 918 participants, led by conductor Jin-Shin You at the Taizhong Jazz Festival in Taiwan in 2008.
A MasterCard spokesperson said: “We’re over the moon that we’ve succeeded in breaking the world record for the longest picnic table today.” The table was comprised of 3,540 screws and 1,230 metres of timber. It has since been divided into multiple tables and will be donated to parks across London.
The Big Lunch, started by the Eden Project, encourages as many people as possible to have lunch with their neighbours. MasterCard added: “We’re delighted to be continuing our partnership with The Big Lunch this year. ”
