Astronomers using European Southern Observatory (ESO) telescopes and other facilities have found clear evidence of a planet orbiting the closest star to Earth, Proxima Centauri. The long-sought world, designated Proxima b, orbits its cool red parent star every 11 days and has a temperature suitable for liquid water to exist on its surface. This rocky world is a little more massive than the Earth and is the closest exoplanet to us -- and it may also be the closest possible abode for life outside the Solar System. 

Just over four light-years from the Solar System lies a red dwarf star that has been named Proxima Centauri as it is the closest star to Earth apart from the Sun. This cool star in the constellation of Centaurus is too faint to be seen with the unaided eye and lies near to the much brighter pair of stars known as Alpha Centauri AB.

During the first half of 2016 Proxima Centauri was regularly observed with the HARPS spectrograph on the ESO 3.6-metre telescope at La Silla in Chile and simultaneously monitored by other telescopes around the world. This was the Pale Red Dot campaign, in which a team of astronomers led by Guillem Anglada-Escudé, from Queen Mary University of London, was looking for the tiny back and forth wobble of the star that would be caused by the gravitational pull of a possible orbiting planet.

As this was a topic with very wide public interest, the progress of the campaign between mid-January and April 2016 was shared publicly as it happened on the Pale Red Dot website and via social media. The reports were accompanied by numerous outreach articles written by specialists around the world.

Guillem Anglada-Escudé explains the background to this unique search: "The first hints of a possible planet were spotted back in 2013, but the detection was not convincing. Since then we have worked hard to get further observations off the ground with help from ESO and others. The recent Pale Red Dot campaign has been about two years in the planning."

The Pale Red Dot data, when combined with earlier observations made at ESO observatories and elsewhere, revealed the clear signal of a truly exciting result. At times Proxima Centauri is approaching Earth at about 5 kilometres per hour -- normal human walking pace -- and at times receding at the same speed. This regular pattern of changing radial velocities repeats with a period of 11.2 days. Careful analysis of the resulting tiny Doppler shifts showed that they indicated the presence of a planet with a mass at least 1.3 times that of the Earth, orbiting about 7 million kilometres from Proxima Centauri -- only 5% of the Earth-Sun distance.

Guillem Anglada-Escudé comments on the excitement of the last few months: "I kept checking the consistency of the signal every single day during the 60 nights of the Pale Red Dot campaign. The first 10 were promising, the first 20 were consistent with expectations, and at 30 days the result was pretty much definitive, so we started drafting the paper!"

Red dwarfs like Proxima Centauri are active stars and can vary in ways that would mimic the presence of a planet. To exclude this possibility the team also monitored the changing brightness of the star very carefully during the campaign using the ASH2 telescope at the San Pedro de Atacama Celestial Explorations Observatory in Chile and the Las Cumbres Observatory telescope network. Radial velocity data taken when the star was flaring were excluded from the final analysis.

Although Proxima b orbits much closer to its star than Mercury does to the Sun in the Solar System, the star itself is far fainter than the Sun. As a result Proxima b lies well within the habitable zone around the star and has an estimated surface temperature that would allow the presence of liquid water. Despite the temperate orbit of Proxima b, the conditions on the surface may be strongly affected by the ultraviolet and X-ray flares from the star -- far more intense than the Earth experiences from the Sun [4].

Two separate papers discuss the habitability of Proxima b and its climate. They find that the existence of liquid water on the planet today cannot be ruled out and, in such case, it may be present over the surface of the planet only in the sunniest regions, either in an area in the hemisphere of the planet facing the star (synchronous rotation) or in a tropical belt (3:2 resonance rotation). Proxima b's rotation, the strong radiation from its star and the formation history of the planet makes its climate quite different from that of the Earth, and it is unlikely that Proxima b has seasons.

This discovery will be the beginning of extensive further observations, both with current instruments and with the next generation of giant telescopes such as the European Extremely Large Telescope (E-ELT). Proxima b will be a prime target for the hunt for evidence of life elsewhere in the Universe. Indeed, the Alpha Centauri system is also the target of humankind's first attempt to travel to another star system, the StarShot project.

Guillem Anglada-Escudé concludes: "Many exoplanets have been found and many more will be found, but searching for the closest potential Earth-analogue and succeeding has been the experience of a lifetime for all of us. Many people's stories and efforts have converged on this discovery. The result is also a tribute to all of them. The search for life on Proxima b comes next..."

The Daily Galaxy via ESO

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The Chinese government has unveiled plans to build a permanently manned radar station on the moon to monitor Earth. The project was launched earlier this year and received funding from the National Natural Science Foundation of China. The proposed facility, which may include quarters for astronauts and a powerful radar antenna array at least 50 meters high, could monitor wider areas of our planet than existing satellites, according to scientists involved in the study.

The base, which would be used for scientific research and defense monitoring, could also produce more powerful and clearer images of earth as the high-frequency microwaves emitted by the radar station could not only penetrate cloud, but also the earth's surface, allowing it to monitor areas on land, under the sea and underground.

Leading space scientists in China have joined the radar station project. The team held a two-day brainstorming session at the Fragrant Hill Hotel in Beijing last month. Those taking part included Yan Jun, the director of the National Astronomical Observatories; Professor Lin Yangting, a planetary researcher whose team discovered evidence of coal-like carbon in an asteroid; and senior scientists from China's unmanned lunar exploration missions. The team leader is Professor Guo Huadong, a top radar technology expert at the Chinese Academy of Sciences.

Guo initially proposed the moon-based radar station in a research paper in the journal Science China Earth Sciences three years ago, suggesting that the moon had numerous advantages over satellites or a space station as an earth observation platform, including stability and the unlimited durability of any complex on the lunar surface.

The data collected by lunar radar would help with a wide range of scientific research issues such as monitoring extreme weather conditions, global earthquake activity, agricultural production and the collapse of the polar ice caps, he wrote.
To generate high intensity radio beams that could reach earth, the radar station would need an enormous amount of power so a solar or nuclear power plant would have to be built, Guo said in the paper.

The radar would generate at least 1.4 gigabytes of data each second, a volume far exceeding the bandwidth of current long-distance space communications technology, but this would not be a problem if the station was manned by astronauts who could process the information on site, he added.

Guo gave no precise estimate on costs for the project, but cautioned it would be “very expensive”. He did not respond to requests for comment.

Many researchers interviewed by the South China Morning Post, however, expressed scepticism about the scheme, arguing it was a waste of money, time and human resources. “It's a lunatic idea,” said one mainland space scientist informed of the project, but not directly involved. The cost of building such as a large scale facility on the moon would be “higher than filling the sky with a constellation of spy satellites”, which could “do the same job at only a fraction of the cost”, said the scientist, who declined to be named due to the sensitivity of the issue.

“Either the radar has to be extremely powerful, or the antenna extremely large, otherwise it won't be able to pick up the radio waves bouncing back from the Earth,” said Professor Zhou Yiguo, a radar technology researcher at the Chinese Academy of Sciences. “It is an important subject of research, but whether its advantage over satellite constellations can adjust the high cost and risk will need careful evaluation.”

The lunar radar project comes as China shows signs of wanting to play a leading role in a renewed race to the moon, according to some space experts.

The design of a giant rocket the same size as the Saturn V in the US Apollo missions will be completed by 2020 to pave way for large scale activities in space including a “manned moon landing”, according to a scientific and technological innovation plan announced by the central government earlier this month.

China's scientific authorities appear optimistic about the prospects for the lunar radar base, despite the concerns voiced by some experts.

The Daily Galaxy via kcwtoday.co and South China Morning Post

Image credit: pics-about-space.com

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Neurons that fire together wire together, say scientists at Columbia University, suggesting that the three-pound computer in our heads may be more malleable than we think. Their findings suggest that groups of activated neurons may form the basic building blocks of learning and memory.

“I always thought the brain was mostly hard-wired,” said the study's senior author, Dr. Rafael Yuste,  who is co-director of the Kavli Institute for Brain Science (KIBS). “But then I saw the results and said ‘Holy moly, this whole thing is plastic.' We're dealing with a plastic computer that's constantly learning and changing.”

The neuroscientists demonstrated that a set of neurons trained to fire in unison could be reactivated as much as a day later if just one neuron in the network was stimulated.

The researchers were able to control and observe the brain of a living mouse using the optogenetic tools that have revolutionized neuroscience in the last decade. They injected the mouse with a virus containing light-sensitive proteins engineered to reach specific brain cells. Once inside a cell, the proteins allowed researchers to remotely activate the neuron with light, as if switching on a TV.

In this photo of living mouse neurons, calcium imaging techniques were used to record the firing of individual neurons and their pulses of electricity. (Credit: Yuste Lab/Columbia University)

The mouse was allowed to run freely on a treadmill while its head was held still under a microscope. With one laser, the researchers beamed light through its skull to stimulate a small group of cells in the visual cortex. With a second laser, they recorded rising levels of calcium in each neuron as it fired, thus imaging the activity of individual cells.
Before optogenetics, scientists had to open the skull and implant electrodes into living tissue to stimulate neurons with electricity and measure their response. Even a mouse brain of 100 million neurons, nearly a thousandth the size of ours, was too dense to get a close look at groups of neurons.

In the above video, neurons repeatedly stimulated with light are trained to work together. They can be reactivated as a group if just one neuron is stimulated as much as a day later. The experiments are detailed in a new study in the journal Science.(Credit: Yuste Lab/Columbia University)

Optogenetics allowed researchers to get inside the brain non-invasively and control it far more precisely. In the last decade, researchers have restored sight and hearing to blind and deaf mice, and turned normal mice aggressive, all by manipulating specific brain regions.

The breakthrough that allowed researchers to reprogram a cluster of cells in the brain is the culmination of more than a decade of work. With tissue samples from the mouse visual cortex, Yuste and his colleagues showed in a 2003 study in Nature that neurons coordinated their firing in small networks called neural ensembles. A year later, they demonstrated that the ensembles fired off in sequential patterns through time.

As techniques for controlling and observing cells in living animals improved, they learned that these neural ensembles are active even without stimulation. They used this information to develop mathematical algorithms for finding neural ensembles in the visual cortex. They were then able to show, as they had in the tissue samples earlier, that neural ensembles in living animals also fire one after the other in sequential patterns.

The current study in Science shows that these networks can be artificially implanted and replayed, says Yuste, much as the scent of a tea-soaked madeleine takes novelist Marcel Proust back to his memories of childhood.

Pairing two-photon stimulation technology with two-photon calcium imaging allowed the researchers to document how individual cells responded to light stimulation. Though previous studies have targeted and recorded individual cells none have demonstrated that a bundle of neurons could be fired off together to imprint what they call a “neuronal microcircuit” in a live animal's brain.

“If you told me a year ago we could stimulate 20 neurons in a mouse brain of 100 million neurons and alter their behavior, I'd say no way,” said Yuste, who is also a member of the Data Science Institute. “It's like reconfiguring three grains of sand at the beach.”

The researchers think that the network of activated neurons they artificially created may have implanted an image completely unfamiliar to the mouse. They are now developing a behavioral study to try and prove this.

“We think that these methods to read and write activity into the living brain will have a major impact in neuroscience and medicine,” said the study's lead author, Luis Carrillo-Reid, a postdoctoral researcher at Columbia.

http://www.kavlifoundation.org/kavli-news/researchers-reprogram-network-brain-cells-thin-beam-light#.V70PaZgrK00

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Find out just how abundant water is in the Cosmos, when cosmochemist Natalie Starkey hosts StarTalk All-Stars for the first time. She's joined by co-host Chuck Nice and planetary scientist Lindy Elkins-Tanton. Get the scoop on new evidence that suggests most of Earth's water didn't come from comets, but rather from the same rocky material that built up our planet. Explore whether a planet is “born wet” or not, and how the formation of a celestial body determines what kind of water it has.

Is the water ice on comets salty, fresh, or just “dirty” with minerals and “gloopy” from complex organic hydrocarbons? Would comets and asteroids be more useful providing water for Earth, or as fueling stations for space exploration, providing hydrogen for fuel, oxygen for breathing and water for drinking?

Natalie and Lindy look at the status of water here on Earth, from pollution, to scarcity, to the lack of regulations protecting our aquifers. And of course, no discussion about space water would be complete without pondering the possibility of life, whether in the ancient subsurface oceans of Jupiter's moon Europa and Saturn's moon Enceladus (below), or on one of the 600 million Earth-like exoplanets scattered throughout the universe. Lindy also shares the story of when she first “made” water in a lab by burning hydrogen, and you'll hear why, for humans, there's no man-made alternative to water.