Kepler bags huge haul of planets.


Four of the planets orbit their host suns in a “habitable zone” where water can keep a liquid state

The science team sifting data from the US space agency’s (Nasa) Kepler telescope says it has identified 715 new planets beyond our Solar System.

This is a huge new haul.

In the nearly two decades since the first so-called exoplanet was discovered, researchers had claimed the detection of just over 1,000 new worlds.

Kepler’s latest bounty are all in multi-planet systems; they orbit only 305 stars.

The vast majority, 95%, are smaller than our Neptune, which is four times the radius of the Earth.

Four of the new planets are less than 2.5 times the radius of Earth, and they orbit their host suns in the “habitable zone” – the region around a star where water can keep a liquid state.

Whether that is the case on these planets cannot be known for sure – Kepler’s targets are hundreds of light-years in the distance, and this is too far away for very detailed investigation.

The Kepler space telescope was launched in 2009 on a $600m (£360m) mission to assess the likely population of Earth-sized planets in our Milky Way Galaxy.

Faulty pointing mechanisms eventually blunted its abilities last year, but not before it had identified thousands of possible, or “candidate”, worlds in a patch of sky in the constellations Cygnus and Lyra.

It did this by looking for transits – the periodic dips in light that occur when planets move across the faces of stars.

Kepler space telescope mission

An illustration of Kepler

Before Wednesday, the Kepler spacecraft had confirmed the existence of 246 exoplanets. It has now pushed this number up to 961. That is more than half of all the discoveries made in the field over the past 20 years.

“This is the largest windfall of planets that’s ever been announced at one time,” said Douglas Hudgins from Nasa’s astrophysics division.

“Second, these results establish that planetary systems with multiple planets around one star, like our own Solar System, are in fact common.

“Third, we know that small planets – planets ranging from the size of Neptune down to the size of the Earth – make up the majority of planets in our galaxy.”

When Kepler first started its work, the number of confirmed planets came at a trickle.

Scientists had to be sure that the variations in brightness being observed were indeed caused by transiting planets and not by a couple of stars orbiting and eclipsing each other.

The follow-up work required to make this distinction – between candidate and confirmation – was laborious.

But the sudden dump of new planets announced on Wednesday has exploited a new statistical approach referred to as “verification by multiplicity”.

This rests on the recognition that if a star displays multiple dips in light, it must be planets that are responsible because it is very difficult for several stars to orbit each other in a similar way and maintain a stable configuration.

“This technique that we’ve introduced for wholesale planet validation will be productive in the future. These results are based on the first two years of Kepler observations and with each additional year, we’ll be able to bring in a few hundred more planets,” explained Jack Lissauer, a planetary scientist at Nasa’s Ames Research Center.

Sara Seager is a professor of planetary science and physics at the Massachusetts Institute of Technology. She is not involved in the Kepler mission.

She commented: “With hundreds of new validated planets, Kepler reinforces its major finding that small planets are extremely common in our galaxy. And I’m super-excited about this, being one of the people working on the next generation of space telescopes – we hope to put up direct imaging missions, and we need to be reassured that small planets are common.”

Detailed information on the latest discoveries has been posted intwopapers on the electronic pre-print arXiv repository.

Graphic
The habitable zone is the region around a star where water can keep a liquid state

Far-Off Planets Like the Earth Dot the Galaxy.


The known odds of something — or someone — living far, far away from Earth improved beyond astronomers’ boldest dreams on Monday.

Astronomers reported that there could be as many as 40 billion habitable Earth-size planets in the galaxy, based on a new analysis of data from NASA’s Kepler spacecraft.

One out of every five sunlike stars in the galaxy has a planet the size of Earth circling it in the Goldilocks zone — not too hot, not too cold — where surface temperatures should be compatible with liquid water, according to a herculean three-year calculation based on data from the Kepler spacecraft by Erik Petigura, a graduate student at the University of California, Berkeley.

Mr. Petigura’s analysis represents a major step toward the main goal of the Kepler mission, which was to measure what fraction of sunlike stars in the galaxy have Earth-size planets. Sometimes called eta-Earth, it is an important factor in the so-called Drake equation used to estimate the number of intelligent civilizations in the universe. Mr. Petigura’s paper, published Monday in the journal Proceedings of the National Academy of Sciences, puts another smiley face on a cosmos that has gotten increasingly friendly and fecund-looking over the last 20 years.

“It seems that the universe produces plentiful real estate for life that somehow resembles life on Earth,” Mr. Petigura said.

Over the last two decades, astronomers have logged more than 1,000 planets around other stars, so-called exoplanets, and Kepler, in its four years of life before being derailed by a mechanical pointing malfunction last winter, has compiled a list of some 3,500 more candidates. The new result could steer plans in the next few years and decades to find a twin of the Earth — Earth 2.0, in the argot — that is close enough to here to study.

The nearest such planet might be only 12 light-years away. “Such a star would be visible to the naked eye,” Mr. Petigura said.

His result builds on a report earlier this year by David Charbonneau and Courtney Dressing of the Harvard-Smithsonian Center for Astrophysics, who found that about 15 percent of the smaller and more numerous stars known as red dwarfs have Earth-like planets in their habitable zones. Using slightly less conservative assumptions, Ravi Kopparapu of Pennsylvania State University found that half of all red dwarfs have such planets.

[Video: Galaxy contains billions of potentially habitable planets, say University of California at Berkeley and University of Hawaii at Manoa astronomers. Watch on YouTube.]

Geoffrey Marcy of the University of California, Berkeley, who supervised Mr. Petigura’s research and was a co-author of the paper along with Andrew Howard of the University of Hawaii, said: “This is the most important work I’ve ever been involved with. This is it. Are there inhabitable Earths out there?”

“I’m feeling a little tingly,” he said.

At a news conference Friday discussing the results, astronomers erupted in praise of the Kepler mission and its team. Natalie Batalha, a Kepler leader from the NASA Ames Research Center, described the project and its members as “the best of humanity rising to the occasion.”

According to Mr. Petigura’s new calculation, the fraction of stars with Earth-like planets is 22 percent, plus or minus 8 percent, depending on exactly how you define the habitable zone.

There are several caveats. Although these planets are Earth-size, nobody knows what their masses are and thus whether they are rocky like the Earth, or balls of ice or gas, let alone whether anything can, or does — or ever will — live on them.

There is reason to believe, from recent observations of other worlds, however, that at least some Earth-size planets, if not all of them, are indeed rocky. Last week, two groups of astronomers announced that an Earth-size planet named Kepler 78b that orbits its sun in 8.5 hours has the same density as the Earth, though it is too hot to support life.

“Nature,” as Mr. Petigura put it, “knows how to make rocky Earth-size planets.”

Also, the number is more uncertain than it might have been because Kepler’s pointing system failed before it could complete its prime survey. As a result, Mr. Petigura and his colleagues had to extrapolate from planets slightly larger than Earth and with slightly smaller, tighter orbits. For the purposes of his analysis “Earth-size” was anything from one to two times the diameter of the Earth, and Earth-like orbits were between 400 and 200 days.

Dr. Batalha said, “We don’t yet have any planet candidates that are exact analogues of the Earth in terms of size, orbit or star type.”

Though Kepler itself is sidelined while astronomers devise a new program it can accomplish with less flexible pointing ability, it has sent back so much data that there is still a whole year’s worth of results left to analyze, Dr. Batalha said. “Scientists,” she said, “are going to work on Kepler data for decades.” Kepler was launched in 2009 to perform a kind of cosmic census, monitoring the brightness of 150,000 far-off stars in the Cygnus and Lyra constellations, looking for dips in brightness when planets pass in front of them.

Mr. Petigura and his colleagues restricted themselves to a subset of some 42,000 brighter and well-behaved stars. They found 603 planets, of which 10 were between one Earth and two Earths in diameter, and circled in what Mr. Petigura defined as the habitable zone, where they would receive between a quarter of the light the Earth gets, and four times as much. In the solar system, that zone would spread from inside the orbit of Venus to just outside the orbit of Mars.

Meanwhile, in an innovation borrowed from other data-intensive fields like particle physics, Mr. Petigura designed a computer pipeline so that he could inject fake planets into the data — 40,000 in all — and see how efficiently his program could detect planets of different sizes and orbits. In addition to that correction, he and his colleagues had to correct for geometry; only about one in 100 planet systems is aligned edge-on so that earthlings would see the telltale wink of an exoplanet transit.

“It was a ton of work,” he recalled, explaining that he had to try out tens of billions of different periods for each star in order to find planets.

Sara Seager, an exoplanet astronomer at the Massachusetts Institute of Technology who was not involved in the work, said the pipeline testing had made the results believable. “I would say that small planets are everywhere and very common,” she said, “no matter how you slice and dice the data. But Kepler is dead and we have no way to get any further data. So we’ll have to be satisfied with this as the final word, for now.”

There may be other planets like ours.


We are not alone.

There are likely “tens of billions” of Earth-like planets in our Milky Way galaxy, according to a study released Monday by astronomers from the University of California-Berkeley and the University of Hawaii.

AP Many Earths

“Planets like our Earth are relatively common throughout the Milky Way galaxy,” said astronomer Andrew Howard of the University of Hawaii, who estimates the number at about 40 billion.

In fact, the nearest Earth-like planet may be “only” 12 light years away, which is roughly 72 trillion miles.

In all, about 8.8 billion stars in our galaxy have planets that are nearly the size of Earth and also have a surface temperature conducive to the development of life. But many more stars (those not similar to our sun) also have planets where life could form, which is where the 40 billion-planet figure comes from.

Like Goldilocks tasting the porridge, temperatures must be “just right” for life to develop: Planets must have a so-called “habitable zone” with “lukewarm temperatures, so that water would not be frozen into ice or vaporized into steam but instead remain a liquid, because liquid water is now understood to be the prerequisite for life,” said Geoffrey Marcy, a professor of astronomy at Berkeley.

The discovery was based on the most accurate statistical analysis yet of all the observations from the Kepler telescope, a space observatory launched in 2009 specifically designed to locate planets around other stars.

The research was based mainly on an exhaustive, three-year search of Kepler data undertaken by Erik Petigura, a graduate student at the University of California, Berkeley.

“Now, for the first time, humanity has a measure of how common Earth-size planets are around sun-like stars,” Marcy added.

Howard says the new estimate of planets means there are 40 billion chances “for life to get started and to evolve.”

“The findings are robust, but you have to read the fine print to understand that the numbers are somewhat uncertain,” noted MIT astronomer Sara Seager, who was not part of the study. “Overall the result speaks to the growing findings that small planets are everywhere.”

“For the past couple of years there has been an emerging consensus that Earth-size planets are common, so in that sense, the result is not hugely surprising,” said astronomer David Kipping of the Harvard-Smithsonian Center for Astrophysics, who was also not part of the study. “What is special about this work is the huge effort of the authors to develop a completely independent way of measuring this occurrence rate to that of the Kepler team.”

And going beyond our galaxy, Marcy reminds us that the Milky Way is just a typical galaxy within our universe, which contains hundreds of billions of galaxies, each of which has about the same number of sun-like stars as does our Milky Way.

“With tens of billions of Earth-like planets in each galaxy, our entire universe must contain billions of billions of Earth-like planets,” Marcy said,

The study was published online Monday in the Proceedings of the National Academy of Sciences using data from the Kepler telescope. The $591 million Kepler telescope is now crippled and nearing the end of its four-year mission.

Astronomers answer key question: How common are habitable planets?


UC Berkeley and University of Hawaii astronomers analyzed all four years of Kepler data in search of Earth-size planets in the habitable zones of sun-like stars, and then rigorously tested how many planets they may have missed. Based on this analysis, they estimate that 22 percent of stars like the sun have potentially habitable Earth-size planets, though not all may be rocky or have liquid water, a presumed prerequisite for life.

NASA’s Kepler spacecraft, now crippled and its four-year mission at an end, nevertheless provided enough data to complete its mission objective: to determine how many of the 100 billion stars in our galaxy have potentially habitable planets.

Based on a statistical analysis of all the Kepler observations, University of California, Berkeley, and University of Hawaii, Manoa, astronomers now estimate that one in five stars like the sun have about the size of Earth and a surface temperature conducive to .

“What this means is, when you look up at the thousands of stars in the night sky, the nearest sun-like star with an Earth-size planet in its habitable zone is probably only 12 light years away and can be seen with the naked eye. That is amazing,” said UC Berkeley graduate student Erik Petigura, who led the analysis of the Kepler data.

“It’s been nearly 20 years since the discovery of the first extrasolar planet around a normal star. Since then we have learned that most stars have planets of some size and that Earth-size planets are relatively common in close-in orbits that are too hot for life,” said Andrew Howard, a former UC Berkeley post-doctoral fellow who is now on the faculty of the Institute for Astronomy at the University of Hawaii. “With this result we’ve come home, in a sense, by showing that planets like our Earth are relatively common throughout the Milky Way galaxy.”

Petigura, Howard and Geoffrey Marcy, UC Berkeley professor of astronomy, will publish their analysis and findings online the week of Nov. 4 in the journal Proceedings of the National Academy of Sciences.

Earth-size may not mean habitable

“For NASA, this number – that every fifth star has a planet somewhat like Earth – is really important, because successor missions to Kepler will try to take an actual picture of a planet, and the size of the telescope they have to build depends on how close the nearest Earth-size planets are,” Howard said. “An abundance of planets orbiting nearby stars simplifies such follow-up missions.”

The team cautioned that Earth-size planets in Earth-size orbits are not necessarily hospitable to life, even if they orbit in the habitable zone of a star where the temperature is not too hot and not too cold.

“Some may have thick atmospheres, making it so hot at the surface that DNA-like molecules would not survive. Others may have rocky surfaces that could harbor liquid water suitable for living organisms,” Marcy said. “We don’t know what range of planet types and their environments are suitable for life.”

Last week, however, Howard, Marcy and their colleagues provided hope that many such planets actually are rocky. They reported that one Earth-size planet discovered by Kepler – albeit, a planet with a likely temperature of 2,000 Kelvin, which is far too hot for life as we know it – is the same density as Earth and most likely composed of rock and iron, like Earth.

“This gives us some confidence that when we look out into the habitable zone, the planets Erik is describing may be Earth-size, rocky planets,” Howard said.

Transiting planets

NASA launched the Kepler space telescope in 2009 to look for planets that cross in front of, or transit, their stars, which causes a slight diminution – about one hundredth of one percent – in the star’s brightness. From among the 150,000 stars photographed every 30 minutes for four years, NASA’s Kepler team reported more than 3,000 planet candidates. Many of these are much larger than Earth – ranging from large planets with thick atmospheres, like Neptune, to gas giants like Jupiter – or in orbits so close to their stars that they are roasted.

To sort them out, Petigura and his colleagues are using the Keck Telescopes in Hawaii to obtain spectra of as many stars as possible. This will help them determine each star’s true brightness and calculate the diameter of each transiting planet, with an emphasis on Earth-diameter planets.

Astronomers use the term “habitable zone” to indicate an orbit not too far from the star such that water freezes, and not too close such that water vaporizes. Habitable zones are orbital areas where the heat from the star creates lukewarm temperatures at which liquid water can exist, and water is the presumed prerequisite for life. Credit: Petigura/UC Berkeley, Howard/UH-Manoa, Marcy/UC Berkeley

Independently, Petigura, Howard and Marcy focused on the 42,000 stars that are like the sun or slightly cooler and smaller, and found 603 candidate planets orbiting them. Only 10 of these were Earth-size, that is, one to two times the diameter of Earth and orbiting their star at a distance where they are heated to lukewarm temperatures suitable for life. The team’s definition of habitable is that a planet receives between four times and one-quarter the amount of light that Earth receives from the sun.

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A census of extrasolar planets

What distinguishes the team’s analysis from previous analyses of Kepler data is that they subjected Petigura’s planet-finding algorithms to a battery of tests in order to measure how many habitable zone, Earth-size planets they missed. Petigura actually introduced fake planets into the Kepler data in order to determine which ones his software could detect and which it couldn’t.

“What we’re doing is taking a census of , but we can’t knock on every door. Only after injecting these fake planets and measuring how many we actually found, could we really pin down the number of real planets that we missed,” Petigura said.

Analysis of four years of precision measurements from Kepler shows that 22±8% of Sun-like stars may have Earth-sized planets in the habitable zone. Credit: Erik A. Petigura.

Accounting for missed planets, as well as the fact that only a small fraction of planets are oriented so that they cross in front of their host star as seen from Earth, allowed them to estimate that 22 percent of all sun-like stars in the galaxy have Earth-size planets in their .

“The primary goal of the Kepler mission was to answer the question, When you look up in the night sky, what fraction of the stars that you see have Earth-size planets at lukewarm temperatures so that water would not be frozen into ice or vaporized into steam, but remain a liquid, because liquid water is now understood to be the prerequisite for life,” Marcy said. “Until now, no one knew exactly how common potentially were around Sun-like stars in the galaxy.”

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All of the potentially habitable planets found in their survey are around K stars, which are cooler and slightly smaller than the sun, Petigura said. But the team’s analysis shows that the result for K stars can be extrapolated to G stars like the sun. Had Kepler survived for an extended mission, it would have obtained enough data to directly detect a handful of Earth-size planets in the habitable zones of G-type stars.

“If the stars in the Kepler field are representative of stars in the solar neighborhood, … then the nearest (Earth-size) planet is expected to orbit a star that is less than 12 light-years from Earth and can be seen by the unaided eye,” the researchers wrote in their paper. “Future instrumentation to image and take spectra of these Earths need only observe a few dozen nearby stars to detect a sample of Earth-size planets residing in the habitable zones of their host stars.”

In January, the team reported a similar analysis of Kepler d

Exoplanet is built like Earth but much, much hotter.


Planet has a similar size and density to our world’s but circles its star in just 8.5 hours.

wo groups of researchers have for the first time succeeded in measuring the mass of an Earth-sized exoplanet — in this case, Kepler-78b, which is only slightly wider than Earth and orbits a star in the constellation Cygnus, 123 parsecs (400 light years) away.

Astronomers are getting better at finding the many small, Earth-sized planets that scatter the Universe outside our Solar System, but finding clues to what they are made of is much harder.

The figures for Kepler-78b are published today in Nature, and show that the planet’s density is similar to that of Earth, suggesting that it also has a similar composition of rock and iron.

That, however, is where the similarities end. Kepler-78b travels in orbit about 40 times closer to its star than Mercury is to the Sun; its year lasts just 8.5 hours; and its surface is thought to reach a scorching 2,300–3,100 Kelvin.

Kepler-78b is one of a recently-discovered class of exoplanets with orbital periods much shorter than one day, says astronomer Francesco Pepe of the University of Geneva in Switzerland, who led one of the teams that calculated the planet’s mass2. “It can be imagined like a lava planet rather than an Earth-like planet,” he says.

It is unclear how Kepler-78b got so close to its star and whether it is falling in further, he adds.

Do the wobble

The mass of an exoplanet is usually calculated on the basis of the ‘wobble’ motion that the orbiting planet’s gravitational pull exerts on its host star — a motion measured as changes in the speed with which the star moves towards or away from Earth by looking at Doppler shifts in the star’s light. The mass of exoplanets the size of Earth is usually hard to estimate because they have a very small influence on their stars. But Kepler-78b — whose size and orbit were first calculated by a team of astronomers in August3 using NASA’s Kepler observatory — is close enough to its star to cause a measurable wobble.

Using data from the High Accuracy Radial Velocity Planet Searcher-North (HARPS-N) spectrograph at the National Galileo Telescope in the Canary Islands, Pepe and his team calculated the planet’s mass at 1.86 times that of the Earth2.

This tallied with results of another team led by astronomer Andrew Howard of the University of Hawaii at Manoa, which put the mass at 1.69 times that of Earth, using data from the High Resolution Eschelle Spectrometer on the Keck 1 Telescope at the W.M. Keck Observatory in Hawaii1.

“This is a very difficult measurement, so someone might be sceptical if only one of us published,” says Howard. The confirmation makes the results “rock solid”, he adds.

Sara Seager, a planetary scientist at the Massachusetts Institute of Technology (MIT) in Cambridge and member of the Kepler science team, says the results represented “an inevitable march towards other Earths”.

“In this case the new discovery may seem like an incremental step,” says Seager, who was not involved in either of the new studies. ”But astronomers are excited because in terms of mass and size and composition it’s the closest to Earth we have, though the orbit is so much different and the planet so much hotter than Earth.”

Earth-like planets in Earth-like orbits are likely to be abundant within the Universe, but because their stars’ corresponding wobble is tiny, finding their mass will considerably more difficult than it was in Kepler-78b’s case.

But Pepe thinks that HARPS-N could find Earth-sized planets in wider orbits, if they belong to “quieter” systems, in which low activity on the surface of the star makes the planets’ influence easier to detect. “If we are very lucky,” he adds.

Source: Nature.

Super-Earth Planet Is More Like Super-Venus, NASA Says.


An alien planet declared a super-Earth by NASA might not be so habitable after all. New measurements flag the planet (called Kepler-69c) as more of a “super-Venus” that would likely be inhospitable to life.

The planetary status change is part of a larger struggle over how to define the habitable zone of a star. In recent years, scientists determined that the distance between a planet and its type of star is just one metric that hints at the likelihood of liquid water on its surface, which could fuel life. Other factors include the planet’s atmosphere and even how the star behaves.

Super-Venus and Super-Earth

“There are a lot of unanswered questions about habitability,” astrophysicist Lucianne Walkowicz, Kepler science team member at Princeton University, said in a statement.

“If the planet gets zapped with radiation all the time by flares from its parent star, the surface might not be a very pleasant place to live. But on the other hand, if there’s liquid water around, that makes a really good shield from high-energy radiation, so maybe life could thrive in the oceans.”

Kepler-69c was, as its name suggests, discovered using the planet-hunting Kepler space telescope. NASA announced the find in April, declaring that the planet is about 1.7 times Earth’s size and “orbits in the habitable zone of a star similar to our sun.” A closer look at the planet’s chemistry, however, showed the planet is actually just outside the habitable zone’s inner edge.

“For example, molecules in a planet’s atmosphere will absorb a certain amount of energy from starlight and radiate the rest back out,” NASA said in a follow-up press release in June. “How much of this energy is trapped can mean the difference between a turquoise sea and erupting volcanoes.”

The researchers also took the star’s energy output and Kepler-69c‘s orbit into account when making the determination. It’s still hard to say for sure if the planet is in the habitable zone, however. A next step could be to look at the atmosphere of the planet itself, but it is difficult for current telescopes to pick up the “signatures” of water, oxygen, carbon dioxide or methane that could indicate life.

Even though the James Webb Space Telescope — slated to launch in 2018 — can examine planetary atmospheres, its capabilities are designed for planets that are far larger than Earth. Probing the atmosphere of Kepler-69c may have to wait for a more sensitive telescope, NASA said.

Stars’ twinkle reveals their character.


In 1806, English poet Jane Taylor famously lamented that a little star’s twinkle left her wondering what it was.

Fast-forward 207 years and a new analysis of starlight collected by NASA’s Kepler space telescope shows patterns in the flicker that are directly tied to the amount of boiling taking place on a star’s surface, a key indicator of its size, mass and evolutionary state.

That information, in turn, reveals volumes about any orbiting planets, including those fortuitously positioned from their parent stars for liquid surface water, apparently a key ingredient for life.

“Everything you know about planets is tied to what you know about the host star,” says Fabienne Bastien, an astronomy graduate student at Vanderbilt University.

“We don’t observe the planets directly. We observe the stars and the influence that the planets have on their stars. So in order to make any conclusions about the size of the planet or the mass of the planet as it’s pulling on the star when it’s moving, you need to know the size and the mass of the star very well.”

“That directly impacts whether or not you can claim that you have an Earth-like planet,” she says.

Bastien, who is working on a doctoral dissertation, was analysing archived Kepler data for a totally different reason when she and colleagues chanced upon strange patterns in the data that they didn’t understand.

“It was a complete surprise,” says Bastien.

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Boiling surfaces

It turns out the pattern provides a quick and relatively reliable way to determine a star’s evolutionary state.

Stars like the Sun, which is about 4.6 billion years old, eventually will evolve into red giants as they run out of fuel for nuclear fusion. The new study shows the surfaces of younger dwarf stars boiling more vigorously than older giants.

“What we are looking at here is the gravitational acceleration in the stellar outer layers, what we often call the atmosphere,” says astronomer Joergen Christensen-Dalsgaard, with Aarhus University in Denmark.

“The typical methods used have uncertainties up to 150 per cent. That very imprecise method is the easiest to do, and especially if you’re dealing with 150,000 stars and you need to characterise them all, that’s what you go to because it takes the least amount of resources. Our technique lets us beat that down to 25 per cent, which is very, very good for this field,” added Bastien.

Kepler, which collected data from about 120,000 target stars between May 2009 and May 2013, was designed to search for Earth-like planets in stars’ habitable zones,

For Bastien’s study, which appears in this week’s edition of Nature, astronomers analysed a few thousand stars in the Kepler data archive.

“If you have a large enough sample, then you start to pick out patterns in the way stars of different evolutionary states behave,” she says.

While the study is based on eight-hour flicker patterns in the visible light coming from target stars, scientists translated the data into corresponding audio wavelengths, a poignant conceptualisation that no doubt would have intrigued, and delighted, poet Taylor.

Source: http://www.abc.net.au