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Science highlights of 2013

Robotic spacecraft, stem cell technology and a watershed moment in climate change dominate this year's list of science stories in 2013. Darren Osborne rates his top 10 science stories of the year.

Singing astronauts, kings buried under council car parks and the smell of popcorn are some of the highlights from the world of science in 2013.

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1. To infinity and beyond

When it was launched in September 1977, the Voyager 1 spacecraft (and its sister Voyager 2) began a journey of the distant giant planets Jupiter, Saturn, Uranus and Neptune, known as the Grand Tour.

Two decades later, both spacecraft had completed their main missions and continued to coast away from the Sun, towards a region between the stars called interstellar space.

Despite a number of 'false starts', NASA announced in June that Voyager 1 had indeed reached beyond the sphere of the Sun's influence, becoming the first human-made object to leave our solar system.

The spacecraft, which is powered by the slow decay of radioactive plutonium, will begin running out of energy for its science instruments in 2020. By 2025, it will be completely out of power.

Read more: Voyager 1 enters unknown territory

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2. 400 ppm and climbing

While politicians continue to debate how best to manage climate change, and scientists fine tune their prediction, there was one piece of irrefutable evidence that emerged during 2013 - our planet's atmosphere contained 400 parts per million of carbon dioxide.

While that may not sound like much, it's the first time our atmosphere has had this level of CO2 for three million years - well before Homo sapiens appeared on the planet.

Ironically, the Mauna Loa Observatory in Hawaii, which has been tracking CO2 levels for the longest continuous period of time - since 1958 - may close due to a lack of funding.

Read more: Carbon pollution hits highest point in 3 million years

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3. Human stems cells created

The therapeutic benefits of human embryonic stem cells have been touted for more than a decade, but the ethics surrounding their 'collection' is still hotly debated.

Some success has been made in the field of induced pluripotent stem cells - converting adult cells back into human stem cells - it is still in its infancy.

In May, an international team of researchers announced they had created human embryonic stem cells using cloning. The team extracted the nuclei from a 'normal' adult stem cell and placed it inside an unfertilised egg that had had its genetic material removed. While the technique had previously been shown to work in monkeys and mice, this was the first time it had successfully done in humans.

Read more: Scientists clone human embryos to make stem cells

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4. Human evolution theories up in the air

A few years ago, our understanding of human evolution was relatively simple. For several thousand years modern humans (Homo sapiens) and Neanderthals roamed the Earth, until 35,000 years ago, when the latter died out in southern Spain.

But recent discoveries about another type of hominin - the Denisovans - are turning that simple story on its head.

In August scientists discovered that humans, in particular those living in South East Asia and the Pacific, have traces of Denisovan DNA. For example, Melanesian people in Papua New Guinea appear to share six per cent of the DNA with Denisovans.

Coupled with previous studies showing that humans from Europe contain fragments of Neanderthal DNA, it paints a complex picture of interbreeding between the hominin species.

Read more: Humans dated ancient Denisovan relatives beyond the Wallace Line

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5. The next wave of space exploration

For more than five decades space exploration has been the domain of the big three: United States, Russia and Europe. But for the last few years a new wave of countries is stepping to the plate.

In January, Iran claimed to have launched a monkey into space - a feat they repeated in December. In September, the Indian Space Agency launched its first interplanetary spacecraft, the Mars Orbital Mission. Two months later, China launched Chang'e 3 with a tiny lunar rover called Yutu, or Jade Rabbit, which became the first rover to touch down on the lunar surface in 40 years.

Private industry is also making big advances in rocketry and spacecraft. SpaceX completed its third docking with the International Space Station (ISS), while Orbital Sciences got its first run on the board with its Cygnus spacecraft also docking with the ISS in April.

Read more: Mythbusting India's Mars mission

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6. English king found under a car park

It was as if the British music group Coldplay was providing the soundtrack with Viva La Vida, when a team of scientists announced that they had found the skeleton the last Plantagenet king of England, Richard III, buried under a non-descript car park in Leicester.

The confirmation came after months of painstaking DNA research, radio carbon dating and examination of historical records.

Further research found microscopic eggs of roundworm parasite in the lower region of the spine where his intestines would have been.

Read more: King Richard III had intestinal worms, researchers reveal

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7. The periodic table got bigger

While 2012 was the year of the Higgs boson, 2013 will be quietly remembered as the year Ununpentium - or element 115 - was confirmed to exist.

Despite having first been created in Russia's Joint Institute for Nuclear Research and the US Lawrence Livermore National Laboratory, it took scientists another 10 years to recreate these short-lived heavy atoms. The atoms were created at the GSI research facility in Germany, by blasting calcium atoms at 90 per cent the speed of light at a foil of americium atoms.

Within a few milliseconds, element 115 decayed into element 113, which in turn broke down into smaller parts.

While the result has no obvious application, it's seen as another step towards our fundamental understanding of the nature at the atomic level.

Read more:Super-heavy weight element confirmed

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8. Ten shades of smell

Most of us know that there are three colour receptors in our retina - red, green and blue - and five basic taste receptors on our tongue - sweet, sour, bitter, salt and umami. This year a group of scientists suggested 10 basic smells.

The researchers took a sample of 144 smell profiles from the Atlas of Odor Character Profiles - a 1985 publication considered as the 'gold standard' for smell - and applied statistical analysis to look for commonalties among the various odours.

The researchers came up with labels such as fragrant, woody or chemical, while other groups were more complicated. For example, one cluster included minty, aniseed, spice, eucalyptus and camphor; while another listed popcorn, smoky, nutty, almond, oily and mouldy.

The team are now looking at the chemical structures behind the smells in an attempt to predict how they 'work', which would be of huge interest to food scientists and the perfume industry.

Read more: Our nose knows ten types of odour

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9. Russia's earth shaking moment

In February, everyone's attention turned to a 'rogue' asteroid named 2012 DA14 that was expected to pass within 27,000 kilometres of the Earth. But less than 24 hours before it made its closest approach, a smaller undetected meteor entered the Earth's atmosphere and exploded over the Russian city of Chelyabinsk, about 1500 kilometres east of Moscow.

The sonic boom created by the 10,000 tonne chunk of space rock blasted windows, destroyed building and injured and more than 1200 people. A few months later, pieces of the meteor were found in a lake nearby.

Although 'impact' was relatively minor - on a cosmic scale at least - it highlights how precarious our place in space is.

Read more: Part of meteor that hit Russia in February pulled from lake in Urals

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10. Size does matter

If there's one thing that men are sensitive about it's the size of one's penis. So a study published in August was of little comfort to those who may appear to be less well-endowed than others.

Australian researchers created a series of computer generated male body shapes, including differing bulgs in the groin region. A cohort of women was then asked to judge which body shapes appealed the most to them. Those that topped the list were body shapes with broad shoulders, and those with large penis bulge.

But before you reach for the tape measure, the researchers point out that penis-size, or other physical attributes, don't necessarily affect how we ultimately select our mates.

Read more: It's official: penis size does matter

Finally, I thought I'd include one of the science video highlights of 2013. In an era where a human living in space is taken for granted - or even forgotten - it took Canadian astronaut Chris Hadfield to remind us how amazing space can be.

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But what about ... ?

There are many great science stories that didn't make the list, in fact I could write another top 10 and still not cover everything. What do you think should have been included? Feel free to add your thoughts in the comments section below.

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