Two million-degree matter from SLAC laser

PICOSECOND PULSE OF DOOM!

From “wow, that’s cold” we now get to meet a “wow, that’s hot” laser application, courtesy of the US Department of Energy’s SLAC National Accelerator Laboratory: its X-ray laser has created and probed matter as hot as the Sun’s corona.

In a busy day at SLAC, the lab announced the creation of 2-million-degree Celsius matter, and also fired the LCLS at neon atoms to create the first “Atomic X-Ray laser”.

One announcement covered the creation of a new kind of laser – the Atomic X-Ray Laser. By firing SLAC’s Linac Coherent Light Source at a capsule of neon gas, the scientists got the neon to emit coherent X-rays.

It works like this: the LCLS’s X-ray pulses knocked electrons out of the inner shells of neon atoms in the target, and when electrons dropped down into the vacated lower-energy orbits, they shed photons. However, instead of the visible light laser we’re familiar with – and which also works by inducing electrons to shed photons as they shed energy – the SLAC technique generated high-energy photons in the X-ray range.

Those X-ray photons then caused similar emissions from neighbouring neon atoms, causing what SLAC’s release calls “a domino effect that amplified the laser light 200 million times”.

The laser X-rays generated by the neon atoms are, the group says, more pure and have one-eighth the wavelength of the laser fired by the LCLS, making it suitable for capturing reactions much faster than have been observed before.

The atomic laser also fulfills a prediction from the earliest days of lasers, that coherent X-rays could be generated by the same phenomena that produces visible coherent light.

The Linac 2M°C chamber. Photo: Sam Vinko and Oxford University

The other SLAC LCLS experiment, announced at the same time, was to fire the instrument at a tiny piece of aluminium foil. The result was a ten-micron cube of a special plasma known as “hot dense matter”.

Very hot, in fact: in the vicinity of 2 million degrees Celsius, similar to the temperature of the Sun’s corona. The LCLS was used to take the temperature of the plasma in the tiny instant – less than a picosecond – for which it existed.

Sam Vincko, a postdoctoral researcher at Oxford University and lead author of the paper demonstrating the hot dense plasma, says the creation of this matter “is important … if we are ultimately to understand the conditions that exist inside stars and at the centre of giant planets within our own solar system and beyond”.

And that was just using LCLS: The Register presumes that once SLAC is able to operate its X-Ray Atomic laser on a routine basis, even higher temperatures will be feasible.

Participants in the plasma research were led by Oxford University, and included scientists from SLAC, Lawrence Berkeley and Lawrence Livermore national laboratories, and five international institutions. The Atomic X-Ray laser was all SLAC’s own work.

Source

New Earth-observing satellite snaps ‘blue marble’ shot

Image of Earth from the Suomi NPP(NASA/NOAA/GSFC/Suomi NPP/VIIRS/Norman Kuring)

The newly renamed Suomi NPP satellite has snapped a hi-res composite of the Earth from a number of swaths over the surface taken on 4 January.

The National Polar-orbiting Operational Environmental Satellite System Preparatory Project, or NPP, was launched at the end of October last year. It was recently renamed the Suomi NPP in honour of the late Verner E Suomi, known as the father of satellite meteorology.

The mission is a bridge between NASA’s Earth Observing System satellites to the next-generation Joint Polar Satellite System, or JPSS, a National Oceanic and Atmospheric Administration (NOAA) programme.

Suomi, who was a meteorologist at the Univerity of Wisconsin, pioneered remote sensing of Earth from satellites in polar orbits a few hundred miles above the surface with Explorer 7 in 1959, and geostationary orbits of thousands of miles with ATS-1 in 1966.

He was also the inventor of the “spin-scan” camera, which allowed geostationary weather satellites to continuously capture snapshots, giving us the pictures commonly used on TV weather forecasts.

“It is fitting that such an important and innovative partnership pays tribute to a pioneer like Verner Suomi,” said Mary Kicza, assistant administrator for NOAA’s Satellite and Information Service.

“Suomi NPP is an extremely important mission for NOAA. Its advanced instruments will improve our weather forecasts and understanding of the climate and pave the way for JPSS, our next generation of weather satellites.”

You can view the full resolution of the image here.

Source

Plan hatched to view Milky Way’s black hole heart

Stargazers to test if Einstein was right

A conference being held this week in Arizona will lay the groundwork for an attempt to visualize the supermassive black hole that resides at the heart of our galaxy.

Since a black hole absorbs light itself, the Event Horizon Telescope (EHT) team is looking for the ring of matter that forms around the perimeter of the structure. If Einstein’s equations behind the General Theory of Relativity are correct, the matter around the edge of the event horizon will form a circle as it spins around the rim.

“Black holes are like babies, they are very messy eaters,” Sheperd Doeleman, principal investigator of the EHT, told The Register. “A lot of what a black hole tries to eat ends up sprayed across the galaxy.”

The EHT program will plan how to coordinate 50 radio telescopes across our planet to focus on the black hole center of our galaxy. This galactic maw has around four million times the mass of our sun and is 26,000 light years away – about 245,979,000,000,000,000 kilometers, give or take a few trillion. Trying to image this from earth is the equivalent looking for a grapefruit on the surface of the moon – catching an image of the black hole’s surroundings will take a telescope over 2,000 times as powerful as Hubble, according to Doeleman.

There are many black holes in our galaxy, but almost all are relatively small and thus hard to spot. It is thought that they originated as stars that went supernova, but the hole at the galactic center is a different kettle of fish, thought to have grown concurrently with the galaxy, and is big enough to be visible.

“We’re hunting big game, we need a large target to see,” Doeleman explained. “The galactic center is the Goldilocks black hole, just at the right distance and mass to resolve the event horizon.”

The team has already conducted a preliminary scan, using three networked radio telescopes, which have determined that there is an object in the target zone. Now many more telescopes are needed to capture the first images of the center of the Milky Way – a project that could be completed in the next three or four years, now that the team has proven that it’s technically possible and that there is an object to study.

Source

Craig Breedlove Going for 800 MPH Land Speed Record in 2013

Craig Breedlove and the "Spirit of America" in 1996

Lately, all of the absolute land speed record talk that we’ve been reading about is in relation to the Bloodhound SSC, a beast of a jet/rocket-engined streamliner with visions of 1,200 mph.

Right now, though, the record stands at 763 mph, leaving several milestones before Bloodhound’s ambitious 1,200-mph goal.

Well, 800 mph is officially in the sights of one man with a whole lot of land speed record credentials. Craig Breedlove was the first to break the 400-mph barrier back in 1963, when he powered the Spirit of America to 408 mph.

Breedlove’s record came at the start of a sort of land speed-record renaissance, and he spent the next two years swapping places with several other teams, eventually breaking the 600-mph barrier in 1965.

While the record has risen over 150 mph since that period, it’s remained at 763 mph since Thrust SSC clocked it back in 1997. Breedlove and his team of engineers attempted to set a record that same year with a redesigned ‘Spirit’, but never made the books due to engine damage.

But Breedlove isn’t done yet. He has some big plans for the 50th anniversary of his first land speed record and will make an attempt at doubling the accomplishment by becoming the first to break 800 mph. Breedlove won’t actually be driving himself but will be part of the engineering team that develops the jet-powered streamliner to do the job.

According to Hemmings, Breedlove and company plan to attempt the record in 2013 at Utah’s Bonneville Salt Flats, where Breedlove set his records in the 1960s.

If you look at the history of the absolute land speed record, it’s a story of intensified efforts during several key periods and subsequent inactivity for years and decades. Breedlove’s 1963 record ended a 16-year drought and was the first of 11 records set over the course of two years. The 1970s, ’80s and ’90s saw one record per decade and there have been none since.

But it looks like we could be on the brink of another renaissance. In addition to Breedlove’s team and the Bloodhound SSC team, several other teams around the world are working on streamliners to take on the speed record. So we could very well see a multitude of world records over the next few years.

 

Source

Billion Light-Year Wide Web of Dark Matter Mapped

By analyzing the light from 10 million galaxies, astronomers have built the largest dark matter map ever created.

Astronomers have created a vast cosmic map revealing an intricate web of dark matter and galaxies spanning a distance of one billion light-years.
This unprecedented task was achieved not by observing dark matter directly, but by observing its gravitational effects on ancient light traveling from galaxies that existed when the Universe was half the age it is now.

Constructed by astronomers from the University of British Columbia and University of Edinburgh, this is the largest dark matter map ever built and took five years to complete.

The research was presented at the American Astronomical Society meeting in Austin, Texas, on Monday.

ANALYSIS: Mapping Dark Matter with a Cosmic Lens

Dark matter pervades the entire observable universe, accounting for 83 percent of the mass of the cosmos. But as it does not scatter or radiate light (or any kind of electromagnetic radiation for that matter), we cannot see it. Naturally, this poses an interesting problem for astronomers hoping to map the stuff.

However, astronomers can indirectly observe dark matter as its mass exerts a gravitational force on the space-time surrounding it. As light travels from distant galaxies, it will be bent around gravitational distortions in space-time — much like the paths of marbles rolling across a bent sheet of plastic — being caused by the dense regions of dark matter.

SCIENCE CHANNEL VIDEO: Dark Energy

With this in mind, the international team of astronomers analyzed light from 10 million galaxies in four different regions of the sky — all of which are around 6 billion light-years from Earth. As these galaxies are six billion light-years away, it took the light six billion years to travel that distance.

ANALYSIS: Dark Matter Mystery Unraveled by Dwarf Galaxies?

Using a 340 Megapixel camera called “MegaCam” attached to the Canada-France-Hawaii Telescope (CFHT) in Hawaii, the ancient galactic light was analyzed to reveal the distorted paths each source traveled thereby revealing the gravitational terrain surrounding clouds of dark matter.

“It is fascinating to be able to ‘see’ the dark matter using space-time distortion,” said Ludovic Van Waerbeke from the University of British Columbia.

“It gives us privileged access to this mysterious mass in the Universe which cannot be observed otherwise.”

Catherine Heymans, from the University of Edinburgh’s School of Physics and Astronomy, added: “By analyzing light from the distant Universe, we can learn about what it has traveled through on its journey to reach us. We hope that by mapping more dark matter than has been studied before, we are a step closer to understanding this material and its relationship with the galaxies in our Universe.”

Both Heymans and Van Waerbeke lead the Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS) team.

ANALYSIS: How Low Can a Dark Matter Halo Go?

It is now hoped that other observatories — such as the Very Large Telescope’s (VLT) Survey Telescope in Chile – will build on the CFHTLenS feat and create an even bigger dark matter map.

“Over the next three years we will image more than 10 times the area mapped by CFHTLenS, bringing us ever closer to our goal of understanding the mysterious dark side of the Universe,” said Koen Kuijken of Leiden University.

Understanding the nature of dark matter is critical to our knowledge of how the Universe evolved to form planets, stars and galaxies. Mapping this vast — yet invisible — cosmic web is a big step in that direction.
Source

Subaru’s sharp eye confirms signs of unseen planets in star’s dust ring

The ring’s offset from the star HR 4796 A is likely the result of one or more planets orbiting in the gap of the ring tugging at its dust grains.

By Subaru Telescope Facility, Hilo, Hawaii — Published: January 4, 2012

Near-infrared (1.6 micron) image of the debris ring around star HR 4796 A. An astronomical unit (AU) is a unit of length that corresponds to the average distance between the Earth and Sun, almost 92 million miles (149 million km). (NAOJ)

 

The Strategic Exploration of Exoplanets and Disks with Subaru Telescope/HiCIAO (SEEDS) project, a five-year international collaboration launched in 2009 and led by Motohide Tamura from the National Astronomical Observatory of Japan (NAOJ) has yielded another impressive image that contributes to our understanding of the link between disks and planet formation. Researchers used Subaru’s planet-finder camera, High Contrast Instrument for the Subaru Next Generation Adaptive Optics (HiCIAO), to take a crisp high-contrast image of the dust ring around HR 4796 A, a young 8- to 10-million-year-old star that is only 240 light-years from Earth. The ring consists of dust grains in a wide orbit, roughly twice the size of Pluto’s orbit, around the central star. The resolution of the image of the inner edge of the ring is so precise that an offset between its center and the star’s position can be measured. Although data from the Hubble Space Telescope led another research group to suspect such an offset, the Subaru data not only confirm its presence, but also reveal it to be larger than previously assumed.

What caused the wheel of dust around HR 4796 A to run off its axis? The most plausible explanation is that the gravitational force of one or more planets orbiting in the gap within the ring must be tugging at the dust grains, thus unbalancing their course around the star in predictable ways. Computer simulations have already shown that such gravitational tides can shape a dust ring into eccentricity, and findings from another — the eccentric dust ring around the star Fomalhaut — may be observational evidence for the process. Since no planet candidates have been spotted near HR 4796 A yet, the planets causing the dust ring to wobble are probably simply too faint to detect with current instruments. Nevertheless, the Subaru image allows scientists to infer their presence from their influence on the circumstellar dust.

The Subaru Telescope’s near-infrared image is as sharp as the Hubble Space Telescope’s visible-light image, thus enabling accurate measurements of its eccentricity. While the Subaru Telescope’s mirror is much larger than Hubble’s, light from the HR 4796 A system must first pass through the turbulent layers of Earth’s atmosphere before Subaru’s instruments can measure it. Subaru’s adaptive optics system allows it to correct for most of the atmosphere’s blurring effects in order to take razor-sharp images. The application of an advanced image processing technique, angular differential imaging, to the data suppressed the star’s bright glare and enhanced the faint light reflected from the ring so that it was more visible.

This image gives scientists more information about the relationship between a circumstellar disk and planet formation. Planets are believed to form in the disks of gas and dust that remain around young stars as the byproducts of star formation. As the material is swept up by the newborn planets or blown out of the system by the star’s radiation, such primordial disks soon disappear in a few tens of million years. Nevertheless, some stars are surrounded by debris or a secondary disk, which is mainly composed of dust long after the primordial disk should have dispersed. Collisions between small solid bodies — planetesimals — left over from planet formation may continuously replenish the dust in these disks. The dust ring around HR 4796 A is such a debris disk and provides essential information for studying planet formation and possible formed planets in such debris disk systems.

Source

New black holes ‘so big nobody believed them for 20 years’

These are the central black holes of NGC 3842 and NGC 4889, and each has a mass close to 10^10 solar masses.

A team led by astronomers at the University of California, Berkeley, discovered the two gigantic black holes in clusters of elliptical galaxies more than 300 million light years away.
But they could not believe their eyes – and the scientific community spent two decades before they accepted what they were seeing.
The previous black hole record-holder was the size of 6 billion suns.
The Oxford University astrophysicist Michele Cappellari, who wrote an accompanying commentary to the research published in the journal Nature, said the findings were at first unbelievable.
“It took a couple of decades to believe that these black holes weren’t just fantasy but actually reality”, he told Radio Four’s Today programme.

In the research, the scientists suggest these black holes may be the leftovers of quasars that crammed the early universe. They are similar in mass to young quasars, they said, and have been well hidden until now.

The scientists used ground-based telescopes as well as the Hubble Space Telescope and Texas supercomputers, observing stars near the black holes and measuring the stellar velocities to uncover these vast, invisible regions.

Black holes are objects so dense that nothing, not even light, can escape. Some are formed by the collapse of a supersize star.

It’s uncertain how these two newly discovered whoppers originated, said Nicholas McConnell, a Berkeley graduate student who is the study’s lead author.

To be so massive now means they must have grown considerably since their formation, he said.

Most if not all galaxies are believed to have black holes at their centre.

The bigger the galaxy, it seems, the bigger the black hole.

Quasars are some of the most energised and distant of galactic centres.

The researchers said their findings suggest differences in the way black holes grow, depending on the size of the galaxy.

“They are monstrous,” Berkeley astrophysicist Chung-Pei Ma told reporters. “We did not expect to find such massive black holes because they are more massive than indicated by their galaxy properties. They’re kind of extraordinary.”

Ma speculates these two black holes remained hidden for so long because they are living in quiet retirement – much quieter and more boring than their boisterous youth powering quasars billions of years ago.

“For an astronomer, finding these insatiable black holes is like finally encountering people nine feet tall whose great height had only been inferred from fossilised bones.

“How did they grow so large?” Ma said in a news release. “This rare find will help us understand whether these black holes had very tall parents or ate a lot of spinach.”

One of the newly detected black holes weighs 9.7 billion times the mass of the sun. The second, slightly farther from Earth, is as big or even bigger.

Even larger black holes may be lurking out there. Ma said that’s the million-dollar question: How big can a black hole grow?

The researchers already are peering into the biggest galaxies for answers.

“If there is any bigger black hole,” Ma said, “we should be able to find them in the next year or two. Personally, I think we are probably reaching the high end now. Maybe another factor of two to go at best.”

Rare Galaxy from ‘Dawn of Time’ Photographed

This image from the Hubble and Spitzer space telescopes shows one of the most distant galaxies known, called GN-108036, dating back to 750 million years after the Big Bang that created our universe. The galaxy's light took 12.9 billion years to reach us. The galaxy's discovery was announced on Dec. 21, 2011. (NASA/JPL-Caltech)

An ancient galaxy that formed just after the birth of the universe has been photographed by telescopes on Earth and in space, and is the brightest galaxy ever seen at such remote distances, astronomers say.

The blob-shaped galaxy, called GN-108036, is about 12.9 billion light-years away and appears as it existed just 750 million years after the universe began. The universe, for comparison, is about 13.7 billion years old.

But the sheer distance to the galaxy isn’t the only thing to intrigue scientists. The galaxy is also creating stars at a furious pace, making it a rare cosmic find. NASA officials described the galaxy as shining from the “dawn of time,” with star formation inside it occurring at a “shockingly high rate.”

A photo of the rare galaxy released by NASA shows the object as a red blob surrounded by other bright galaxies.

Source

Large Hadron Collider Discovers First New Particle

European Center for Nuclear Research (CERN) scientists control computer screens showing traces on Atlas experiment of the first protons injected in the Large Hadron Collider (LHC) during its switch on operation in CERN's control room, near Geneva, Switzerland.

The Large Hadron Collider (LHC), famously engaged in the quest for the Higgs boson, has turned up a heavier variant of a sub-atomic particle first discovered a quarter-century ago, scientists reported Thursday.
The newcomer is called Chi-b(3P), which was uncovered in the debris from colliding protons, according to research published in the open-access online journal arXiv.

Like the elusive Higgs and the photon, it is a boson, meaning it is a particle that carries force.
But while the Higgs is not believed to be made of smaller particles, the Chi-b(3) comprises two relatively heavy particles, the beauty quark and its antiquark.
They are bonded by the so-called “strong” force which also causes the atomic nucleus to stick together.
The Chi-b(3P) is a heavier version of a particle that was first observed around 25 years ago.
“The Chi-b(3P) is a particle that was predicted by many theorists, but was not observed at previous experiments,” said James Walder, a British physicist quoted by the University of Birmingham in a press release.
Described by some as the world’s largest machine, the LHC is located in a 17-mile (27km) ring-shaped tunnel near Geneva that straddles the Franco-Swiss border up to 580 feet (175m) below ground.
Streams of protons are fired in opposite, but parallel, directions in the tunnel.
The beams are then bent by powerful magnets so that some of the protons collide in four giant labs, which are lined with detectors to record the sub-atomic debris that results.
On December 13, physicists at the European Organization for Nuclear Research (CERN) said they had narrowed the search for the Higgs — the so-called “God particle” that may confer mass.
The theory behind the Higgs is that mass does not derive from particles themselves.
Instead, it comes from a boson that interacts strongly with some particles but less, if at all, with others.
Finding the Chi-b(3P) is a further test of the powers of the LHC, which became the world’s biggest particle collider when it was completed in 2008.
“Our new measurements are a great way to test theoretical calculations of the forces that act on fundamental particles, and will move us a step closer to understanding how the Universe is held together,” said Miram Watson, a British research fellow working on the CHi-b(3) investigation.
A massive collaborative effort that brings in physicists from around the world, the LHC has cost more than 6.03 billion Swiss francs (roughly $4.5 billion).

Source

First Ever ‘Earth-Sized’ Alien Planets Discovered

This illustrated graphic shows the two newfound Kepler-20 planets shown to scale with Earth and Venus.

Two planets orbiting a star 950 light-years from Earth are the smallest, most Earth-size alien worlds known, astronomers announced Tues., Dec. 20. One of the planets is actually smaller than Earth, scientists say.
These planets, while roughly the size of our planet Earth, are circling very close to their star, giving them fiery temperatures that are most likely too hot to support life, researchers said. The discovery, however, brings scientists one step closer to finding a true twin of Earth that may be habitable.

“We’ve crossed a threshold: For the first time, we’ve been able to detect planets smaller than the Earth around another star,” lead researcher François Fressin of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., told SPACE.com. “We proved that Earth-size planets exist around other stars like the sun, and most importantly, we proved that humanity is able to detect them. It’s the beginning of an era.”
To discover the new planets, Fressin and his colleagues used NASA’s Kepler space telescope, which noticed the tiny dips in the parent star’s brightness when the planets passed in front of it, blocking some of its light (this is called the transit method). The researchers then used ground-based observatories to confirm that the planets actually exist by measuring minute wobbles in the star’s position caused by gravitational tugs from its planets.
“These two new planets are the first genuinely Earth-sized worlds that have been found orbiting a sunlike star,” University of California, Santa Cruz astronomer Greg Laughlin, who was not involved in the new study, said in an email to SPACE.com. “For the past two decades, it has been clear that astronomers would eventually reach this goal, and so it’s fantastic to learn that the detection has now been achieved.” [Gallery: Smallest Alien Planets Ever Seen]
Chances for life
The two Earth-size planets are among five alien worlds orbiting a star called Kepler-20 that is of the same class (G-type) as our sun, and is slightly cooler.
Two of the star system’s planets, Kepler-20e and Kepler-20f, are 0.87 times and 1.03 times the width of Earth, respectively, making them the smallest exoplanets yet known. They also appear to be rocky, and have masses less than 1.7 and 3 times Earth’s mass, respectively.
Kepler-20e makes a circle around its star once every 6.1 days at a distance of 4.7 million miles (7.6 million kilometers) — almost 20 times closer than Earth, which orbits the sun at around 93 million miles (150 million km).
The planet’s sibling, Kepler-20f, makes a full orbit every 19.6 days, at a distance of 10.3 million miles (16.6 million km). Both planets circle closer to their star than Mercury does to the sun. [Infographic: Earth-Size Alien Planets Explained]
These snuggly orbits around their star give the newfound planets steamy temperatures of about 1,400 degrees Fahrenheit (760 degrees Celsius) and 800 degrees Fahrenheit (430 degrees Celsius) — way too warm to support liquid water, and probably life, researchers said.
Fressin said the chance of life on either of these planets is “negligible,” though the researchers can’t exclude the possibility that they used to be habitable in the past, when they might have been farther from their star. There is also a slim chance that there are habitable regions on the planets in spots between their day and night sides (the planets orbit with one half constantly facing their star and the other half always in dark). But astronomers aren’t holding out hope.
“The chances of liquid water and life as we know it on Kepler-20e and f are zero,” Laughlin said.
Flip-flopped planets
The planetary system around Kepler-20 is an unusual one.
For one thing, scientists say the rocky planets can’t have formed in their current locations.
“There’s not enough rocky material that close to the host star to form five planets,” Fressin said. “They didn’t form here; they probably formed farther from their star and migrated in.”
Furthermore, the five planets are in an odd order, with the rocky worlds alternating with their gaseous, Neptune-size siblings. That’s quite different from most solar systems, including our own, which keeps the rocky terrestrial worlds in close to the sun, with the gas giants farther out.
“How did that form?” Fressin said. “I think it’s a puzzle the theorists will have to try to explain.”
The star’s other planets are called Kepler-20b, 20c, and 20d. Their diameters are 15,000 miles (24,000 km), 24,600 miles (40,000 km), and 22,000 miles (35,000 km), respectively, and they orbit Kepler-20 once every 3.7, 10.9, and 77.6 days.
The largest of these, Kepler-20d, weighs a little under 20 times Earth’s mass, while Kepler-20c is 16.1 times as heavy as Earth, and Kepler-20b is 8.7 times our planet’s mass.
Evolving effort
Scientists say finding the smallest exoplanets yet represents a significant milestone in the fast-evolving effort to learn about planets beyond the solar system.
The first alien planet was discovered in 1996, and the first planet found through the transit method came just 11 years ago. Both of those planets were roughly the size of Jupiter.
“I think we’re living in special times,” Fressin said. “This was unfeasible 10 years ago, and just with the quality of detectors and the quality of the treatment is it possible now.”
The total tally of known alien planets is above 700. Kepler alone has discovered 28 definite alien planets, and 2,326 planet candidates, since its launch in March 2009.
Earlier this month, the Kepler team announced another landmark find, the first planet known to occupy the habitable zonearound its star where liquid water, and perhaps life, could exist.
That planet, called Kepler-22b, is about 2.4 times as wide as Earth.
The dream now is for astronomers to combine the two discoveries and find an Earth-size planet that’s also orbiting its star in an Earth-like orbit that puts it in the habitable zone.
“The holy grail of the search for other worlds is to find an Earth analogue, a true Earth twin,” Fressin said. “We just need to have these two pieces of the puzzle together.”
While the newfound planets orbit with periods of 6.1 and 19.6 days, Fressin estimated the habitable zone around Kepler-20 begins at orbits that take roughly 100 days to make a circuit.
Astronomers think it’s only a matter of time before they finally find one that’s just right.
“These discoveries are a great technological step forward — to detect small planets, in size like Earth — but these planets are very hot and not in the habitable zone around their star,” astronomer Lisa Kaltenegger of the Harvard-Smithsonian Center for Astrophysics wrote in an email. Kaltenegger, who studies the habitability of exoplanets, was not involved in the new study. “If we can already find these small planets with radii around Earth’s now, some future ones could be in the habitable zone of their stars and THOSE future ones would be great targets to look for liquid water and signatures for life.”
A paper detailing the discovery was published online in the journal Nature Dec. 20.

Source