Quantum Entanglement
Time’s Arrow Traced to Quantum Source
Natalie Wolchover, Quanta Magazine
Coffee cools, buildings crumble, eggs break and stars fizzle out in a universe that seems destined to degrade into a state of uniform drabness known as thermal equilibrium. The astronomer-philosopher Sir Arthur Eddington in 1927 cited the gradual dispersal of energy as evidence of an irreversible “arrow of time.”
But to the bafflement of generations of physicists, the arrow of time does not seem to follow from the underlying laws of physics, which work the same going forward in time as in reverse. By those laws, it seemed that if someone knew the paths of all the particles in the universe and flipped them around, energy would accumulate rather than disperse: Tepid coffee would spontaneously heat up, buildings would rise from their rubble and sunlight would slink back into the sun.
“In classical physics, we were struggling,” said Sandu Popescu, a professor of physics at the University of Bristol in the United Kingdom. “If I knew more, could I reverse the event, put together all the molecules of the egg that broke? Why am I relevant?”
Surely, he said, time’s arrow is not steered by human ignorance. And yet, since the birth of thermodynamics in the 1850s, the only known approach for calculating the spread of energy was to formulate statistical distributions of the unknown trajectories of particles, and show that, over time, the ignorance smeared things out.
Now, physicists are unmasking a more fundamental source for the arrow of time: Energy disperses and objects equilibrate, they say, because of the way elementary particles become intertwined when they interact — a strange effect called “quantum entanglement.”
“Finally, we can understand why a cup of coffee equilibrates in a room,” said Tony Short, a quantum physicist at Bristol. “Entanglement builds up between the state of the coffee cup and the state of the room.”
Popescu, Short and their colleagues Noah Linden and Andreas Winter reported the discovery in the journal Physical Review E in 2009, arguing that objects reach equilibrium, or a state of uniform energy distribution, within an infinite amount of time by becoming quantum mechanically entangled with their surroundings. Similar results by Peter Reimann of the University of Bielefeld in Germany appeared several months earlier in Physical Review Letters. Short and a collaborator strengthened the argument in 2012 by showing that entanglement causes equilibration within a finite time. And, in work that was posted on the scientific preprint site arXiv.org in February, two separate groups have taken the next step, calculating that most physical systems equilibrate rapidly, on time scales proportional to their size. “To show that it’s relevant to our actual physical world, the processes have to be happening on reasonable time scales,” Short said.
The tendency of coffee — and everything else — to reach equilibrium is “very intuitive,” said Nicolas Brunner, a quantum physicist at the University of Geneva. “But when it comes to explaining why it happens, this is the first time it has been derived on firm grounds by considering a microscopic theory.”
If the new line of research is correct, then the story of time’s arrow begins with the quantum mechanical idea that, deep down, nature is inherently uncertain. An elementary particle lacks definite physical properties and is defined only by probabilities of being in various states. For example, at a particular moment, a particle might have a 50 percent chance of spinning clockwise and a 50 percent chance of spinning counterclockwise. An experimentally tested theorem by the Northern Irish physicist John Bell says there is no “true” state of the particle; the probabilities are the only reality that can be ascribed to it.
Quantum uncertainty then gives rise to entanglement, the putative source of the arrow of time.
When two particles interact, they can no longer even be described by their own, independently evolving probabilities, called “pure states.” Instead, they become entangled components of a more complicated probability distribution that describes both particles together. It might dictate, for example, that the particles spin in opposite directions. The system as a whole is in a pure state, but the state of each individual particle is “mixed” with that of its acquaintance. The two could travel light-years apart, and the spin of each would remain correlated with that of the other, a feature Albert Einstein famously described as “spooky action at a distance.”
“Entanglement is in some sense the essence of quantum mechanics,” or the laws governing interactions on the subatomic scale, Brunner said. The phenomenon underlies quantum computing, quantum cryptography and quantum teleportation.
The idea that entanglement might explain the arrow of time first occurred to Seth Lloyd about 30 years ago, when he was a 23-year-old philosophy graduate student at Cambridge University with a Harvard physics degree. Lloyd realized that quantum uncertainty, and the way it spreads as particles become increasingly entangled, could replace human uncertainty in the old classical proofs as the true source of the arrow of time.
Using an obscure approach to quantum mechanics that treated units of information as its basic building blocks, Lloyd spent several years studying the evolution of particles in terms of shuffling 1s and 0s. He found that as the particles became increasingly entangled with one another, the information that originally described them (a “1” for clockwise spin and a “0” for counterclockwise, for example) would shift to describe the system of entangled particles as a whole. It was as though the particles gradually lost their individual autonomy and became pawns of the collective state. Eventually, the correlations contained all the information, and the individual particles contained none. At that point, Lloyd discovered, particles arrived at a state of equilibrium, and their states stopped changing, like coffee that has cooled to room temperature.
“What’s really going on is things are becoming more correlated with each other,” Lloyd recalls realizing. “The arrow of time is an arrow of increasing correlations.”
The idea, presented in his 1988 doctoral thesis, fell on deaf ears. When he submitted it to a journal, he was told that there was “no physics in this paper.” Quantum information theory “was profoundly unpopular” at the time, Lloyd said, and questions about time’s arrow “were for crackpots and Nobel laureates who have gone soft in the head.” he remembers one physicist telling him.
“I was darn close to driving a taxicab,” Lloyd said.
Advances in quantum computing have since turned quantum information theory into one of the most active branches of physics. Lloyd is now a professor at the Massachusetts Institute of Technology, recognized as one of the founders of the discipline, and his overlooked idea has resurfaced in a stronger form in the hands of the Bristol physicists. The newer proofs are more general, researchers say, and hold for virtually any quantum system.
“When Lloyd proposed the idea in his thesis, the world was not ready,” said Renato Renner, head of the Institute for Theoretical Physics at ETH Zurich. “No one understood it. Sometimes you have to have the idea at the right time.”
In 2009, the Bristol group’s proof resonated with quantum information theorists, opening up new uses for their techniques. It showed that as objects interact with their surroundings — as the particles in a cup of coffee collide with the air, for example — information about their properties “leaks out and becomes smeared over the entire environment,” Popescu explained. This local information loss causes the state of the coffee to stagnate even as the pure state of the entire room continues to evolve. Except for rare, random fluctuations, he said, “its state stops changing in time.”
Consequently, a tepid cup of coffee does not spontaneously warm up. In principle, as the pure state of the room evolves, the coffee could suddenly become unmixed from the air and enter a pure state of its own. But there are so many more mixed states than pure states available to the coffee that this practically never happens — one would have to outlive the universe to witness it. This statistical unlikelihood gives time’s arrow the appearance of irreversibility. “Essentially entanglement opens a very large space for you,” Popescu said. “It’s like you are at the park and you start next to the gate, far from equilibrium. Then you enter and you have this enormous place and you get lost in it. And you never come back to the gate.”
In the new story of the arrow of time, it is the loss of information through quantum entanglement, rather than a subjective lack of human knowledge, that drives a cup of coffee into equilibrium with the surrounding room. The room eventually equilibrates with the outside environment, and the environment drifts even more slowly toward equilibrium with the rest of the universe. The giants of 19th century thermodynamics viewed this process as a gradual dispersal of energy that increases the overall entropy, or disorder, of the universe. Today, Lloyd, Popescu and others in their field see the arrow of time differently. In their view, information becomes increasingly diffuse, but it never disappears completely. So, they assert, although entropy increases locally, the overall entropy of the universe stays constant at zero.
“The universe as a whole is in a pure state,” Lloyd said. “But individual pieces of it, because they are entangled with the rest of the universe, are in mixtures.”
One aspect of time’s arrow remains unsolved. “There is nothing in these works to say why you started at the gate,” Popescu said, referring to the park analogy. “In other words, they don’t explain why the initial state of the universe was far from equilibrium.” He said this is a question about the nature of the Big Bang.
Despite the recent progress in calculating equilibration time scales, the new approach has yet to make headway as a tool for parsing the thermodynamic properties of specific things, like coffee, glass or exotic states of matter. (Several traditional thermodynamicists reported being only vaguely aware of the new approach.) “The thing is to find the criteria for which things behave like window glass and which things behave like a cup of tea,” Renner said. “I would see the new papers as a step in this direction, but much more needs to be done.”
Some researchers expressed doubt that this abstract approach to thermodynamics will ever be up to the task of addressing the “hard nitty-gritty of how specific observables behave,” as Lloyd put it. But the conceptual advance and new mathematical formalism is already helping researchers address theoretical questions about thermodynamics, such as the fundamental limits of quantum computers and even the ultimate fate of the universe.
“We’ve been thinking more and more about what we can do with quantum machines,” said Paul Skrzypczyk of the Institute of Photonic Sciences in Barcelona. “Given that a system is not yet at equilibrium, we want to get work out of it. How much useful work can we extract? How can I intervene to do something interesting?”
Sean Carroll, a theoretical cosmologist at the California Institute of Technology, is employing the new formalism in his latest work on time’s arrow in cosmology. “I’m interested in the ultra-long-term fate of cosmological space-times,” said Carroll, author of “From Eternity to Here: The Quest for the Ultimate Theory of Time.” “That’s a situation where we don’t really know all of the relevant laws of physics, so it makes sense to think on a very abstract level, which is why I found this basic quantum-mechanical treatment useful.”
Twenty-six years after Lloyd’s big idea about time’s arrow fell flat, he is pleased to be witnessing its rise and has been applying the ideas in recent work on the black hole information paradox. “I think now the consensus would be that there is physics in this,” he said.
Not to mention a bit of philosophy.
According to the scientists, our ability to remember the past but not the future, another historically confounding manifestation of time’s arrow, can also be understood as a buildup of correlations between interacting particles. When you read a message on a piece of paper, your brain becomes correlated with it through the photons that reach your eyes. Only from that moment on will you be capable of remembering what the message says. As Lloyd put it: “The present can be defined by the process of becoming correlated with our surroundings.”
The backdrop for the steady growth of entanglement throughout the universe is, of course, time itself. The physicists stress that despite great advances in understanding how changes in time occur, they have made no progress in uncovering the nature of time itself or why it seems different (both perceptually and in the equations of quantum mechanics) than the three dimensions of space. Popescu calls this “one of the greatest unknowns in physics.”
“We can discuss the fact that an hour ago, our brains were in a state that was correlated with fewer things,” he said. “But our perception that time is flowing — that is a different matter altogether. Most probably, we will need a further revolution in physics that will tell us about that.”
Dinosaur Illustrations
Acrotholus audeti and Neurankylus lithographicus. (Digital photographic compositing. Evans et al, 2013). One of the pleasures of working closely with paleontologists is that I get to be “in the loop” about new discoveries even before they go to print in research journals. This is gratifying because it allows me to still keep a foot firmly in the camp of active science even though I am not currently engaged in the research for which my graduate training in ecology and microbiology prepared me. This piece is an example of artwork that was commissioned by Dr. David Evans to appear in press releases in order to boost public knowledge of his research, helping to spread the word through newspapers, television and digital media much farther than would publication solely in a scientific journal. This scene shows the newly described dome-headed dinosaur, Acrotholus, exiting a stand of giant Gunnera leaves and coming across a Neurankylus turtle soaking in a footprint of a hadrosaur that had passed by earlier. JULIUS CSOTONYI
Carcharocles megalodon snacking on Platybelodon in Miocene waters. (Photographic compositing. Hall of Paleontology at the Houston Museum of Natural Science, 2012). One of 14 of my images appearing as backlit panels (about 4 feet tall) in the museum, this image depicts the probably rare but plausible encounter between the giant shark Carcharocles (jaw diameter estimated at 11 feet) and a medium-sized proboscidean, Platybelodon. Whereas adult sharks likely dined over deep water, relegating their young to the safety of nurseries in shallow lagoons, it is plausible that an adult could enter shallow water occasionally, especially under stress. JULIUS CSOTONYI
Suchomimus and Kryptops. (Digital Painting, 2013). A Cretaceous Nigerian scene depicting a young (and speculatively feathered) abelisaurid called Kryptops disturbed from its drinking by the commotion caused by a Suchomimus plucking a young Sarcosuchus from its river habitat. This image was meant to break the unnecessary custom of nearly always showing the crocodilian-like snouted Suchomimus hunting fish of one sort or another. I do not see why it could not have hunted anything of about the right size, even a young Sarcosuchus (which, in adult form, would turn the tables and pose a greater threat to Suchomimus than the other way around). JULIUS CSOTONYI
Utahraptor attacking Hippodraco in sand dewatering feature. (Digital painting. Dr. James Kirkland, 2013). This image endeavors to restore some of the events leading to the creation of a large block of highly fossiliferous sandstone (containing Utahraptor over a range of ontogenetic stages and Hippodraco) from the Cretaceous in what is now Utah. The futile struggles of a Hippodraco draw the interest of a pack of Utahraptor , all of which will ultimately become mired in the quicksand. JULIUS CSOTONYI
Dimetrodon dawn. (Digital painting. Gondwana Studios, Australia, 2011). One of two marketing images created for Gondwana Studios’ travelling exhibit, “Permian Monsters: Life Before the Dinosaurs”. This image shows a lone Dimetrodon ready to begin sunning itself on an early Permian morning. JULIUS CSOTONYI
Lythronax investigating Squalicorax. (Photographic compositing, 2013). On a beach in Laramidia during the Cretaceous, in what is now Utah, a pair of Lythronax argestes moves in to investigate the stranded carcass of a large Squalicoraxshark, which is already being picked at by a pair of enantiornithine birds. Although protofeathers are not known from Lythronax, phylogenetic bracketing suggests their presence in tyrannosaurids in general, so I chose to give Lythronax a stubble of downy feathers. JULIUS CSOTONYI
Early Permian landscape. (Photographic compositing. Gondwana Studios, Australia, 2011). One of eleven murals created for Gondwana Studios’ travelling exhibit, “Permian Monsters: Life Before the Dinosaurs”. This image features the bizarre sight of Meganeuropsis carrying Hylonomus, and Eryops leaping after them.
JULIUS CSOTONYI
JULIUS CSOTONYI
Albertonectes in the Bearpaw Sea. (Digital photographic compositing. Pipestone Creek Dinosaur Initiative in support of the Phillip J. Currie Dinosaur Museum, Grande Prairie, Alberta, Canada, 2012). It’s been rewarding to be involved in the fund raising efforts of Brian Brake’s team on the way to making a long-awaited dream come true: the building of Canada’s newest paleontological museum, the Phillip J. Currie Dinosaur Museum, just off the Alaska Highway. This piece, commissioned to be sold as prints for fund-raising, depicts the extremely long-necked plesiosaur, Albertonectes, hunting fish in the Bearpaw Sea, a Late Cretaceous environment of the Western Interior Seaway that once covered much of Alberta and that is an exceptionally well known paleo-ecosystem from the fossil record. JULIUS CSOTONYI
Permian dicynodonts. (Photographic compositing. Gondwana Studios, Australia, 2011). Created for Gondwana Studios’ travelling exhibit, “Permian Monsters,” this image features a group of the synapsid Dicynodon warily eying the early archosaur Archosaurus as it snaps up a breaching Saurichthys, while a Chroniosuchus hangs out in the stream shallows. JULIUS CSOTONYI
Mei long, first published specimen. (Digital painting. Non-commissioned, 2007). An illustration of the first published specimen of the troodontid Mei long, a name which in Chinese means “sleeping dragon.” It comes from the Yixian formation in China, amazingly in a posture similar to that adopted by sleeping birds of today. In this reconstruction, I wished to illustrate the concept of cryptic coloration, referring to the color patterns of an animal closely matching those of its surrounding, and which is employed by modern animals to hide from predators or prey. It would have been a useful trait for small theropods that slept on the ground, unless they had other means of hiding, such as inhabiting burrows or other concealing cover. JULIUS CSOTONYI
The Large Magellanic Cloud
Nearly 200,000 light-years from Earth, the Large Magellanic Cloud, a satellite galaxy of the Milky Way, floats in space, in a long and slow dance around our galaxy. Vast clouds of gas within it slowly collapse to form new stars. In turn, these light up the gas clouds in a riot of colors, visible in this image from the NASA/ESA Hubble Space Telescope.
The Large Magellanic Cloud (LMC) is ablaze with star-forming regions. From the Tarantula Nebula, the brightest stellar nursery in our cosmic neighborhood, to LHA 120-N 11, part of which is featured in this Hubble image, the small and irregular galaxy is scattered with glowing nebulae, the most noticeable sign that new stars are being born.
Image Credit: ESA/NASA/Hubble
M51
The Chandra X-ray telescope captured this stunning view of Messier 51.
Credit: X-ray: NASA/CXC/Wesleyan Univ./R.Kilgard, et al; Optical: NASA/STScI
Credit: Lowell Observatory
Whirlpool Galaxy: Exploding With Supernovas
by Elizabeth Howell, SPACE.com | April 15, 2014 01:29am ET
The Whirlpool Galaxy is a spiral galaxy that is relatively close to Earth — about 30 million light-years away. It is visible in the northern constellation Canes Venatici, just southeast of the Big Dipper.
More properly known as M51 or NGC 5194, the galaxy is noted as "one of the brightest and most picturesque" ones that Earthlings can see, according to NASA. The Space Telescope Science Institute (STScI) calls it one of "astronomy's galactic darlings."
Among astrophysicists, one of the Whirlpool's highlights is the abundance of supernovas (star explosions) that have been recorded there in recent years. It also is noted for its closeness to companion galaxy NGC 5195, which may be affecting the structure of the Whirlpool itself.
'Spiral nebula'
M51 was first catalogued by Charles Messier in 1773 while the astronomer was plotting objects in the sky that could confuse comet-hunters. "M51" is a reference to "Messier 51," one of about 110 entries now plotted in his Catalogue of Nebulas and Star Clusters. (The companion NGC 5195 was discovered in 1781 by Pierre Méchain, who the University of Manitoba describes as a close friend to Messier.)
It would take about 70 years to learn more about the fuzzy object's structure, however. It was first discerned by William Parsons, 3rd earl of Rosse, using a 72-inch reflector telescope in 1845. "His drawing of the spiral galaxy M51 is a classic work of mid-19th-century astronomy," said Encyclopedia Britannica of Parsons' observations.
Parsons' discovery was the first so-called "spiral nebula" ever discovered, and in the five years following he found 14 more of these objects, according to the STScI. It was unclear for decades if these objects were a part of the Milky Way Galaxy or things that were independent of that.
It wasn't until Edwin Hubble used Cepheid variable stars to chart cosmic distances in M31 (the Andromeda Galaxy) in the 1920s that astronomers understood they were actually distant galaxies.
Whirpool galaxy before and after supernova
The Whirlpool galaxy (M51) before (left) and after (right) the eruption of supernova SN 2011dh in May 2011. The image on the left was taken in 2009, and on the right July 8th, 2011.
Credit: Conrad Jung
Supernova bonanza
There's been a veritable cornucopia of supernovas in the Whirlpool in recent years. Skywatchers recorded supernovas in 1994, 2005 and 2011.
"Three supernovas in 17 years is a lot for single galaxy, and reasons for the supernova surge in M51 are being debated," noted the NASA website Astronomy Picture of the Day in 2011, without elaborating on the possible explanations.
The latest supernova, called SN 2011dh, was at its brightest in June 2011 before slipping back into obscurity. After the event, astronomers scoured older pictures to see if they could find the source of the explosion. They narrowed their search to a yellow supergiant star (visible in Hubble Space Telescope pictures) that was there before the explosion, and appears to be missing afterwards.
While most yellow supergiants aren't expected to go supernova when they finish out their lives, the team said it's possible that the star was actually a binary star. The other star would have been a bluer, hotter star that was close enough to pull some of the yellow supergiant's mass away. Given enough time, this would have destabilized the star and caused the explosion, astronomers said.
The blue star wasn't spotted in Hubble photos, but astronomers added that it is likely best visible in ultraviolet light — a band of light that Hubble does not look at.
"The present results reveal the necessity and importance of further studyingthe evolution and explosion of binary stars," said Melina Bersten of the Kavli Institute for the Physics and Mathematics of the Universe in Japan, who led the team, in a statement. "I look forward to the observation that will confirm our prediction."
Close encounter of the galactic kind
The Whirlpool's arms are one of the more prominent observed in spiral galaxies, STScI noted. The group said this could be because of what they termed a "close encounter" with its companion galaxy, NGC 5195.
"As NGC 5195 drifts by, its gravitational muscle pumps up waves within the Whirlpool's pancake-shaped disk. The waves are like ripples in a pond generated when a rock is thrown in the water," STScI stated.
"When the waves pass through orbiting gas clouds within the disk, they squeeze the gaseous material along each arm's inner edge. The dark dusty material looks like gathering storm clouds. These dense clouds collapse, creating a wake of star birth."
Over time, the biggest stars would then radiate away the surrounding gas, leaving behind blue star clusters that are easily visible in the Whirlpool's arms, STScI added. More generally, the fact that the galaxy is so close by allows astronomers to look at its structure and way it forms stars, with the aim of extrapolating that understanding to other galaxies.
Blood Moon
Skywatching 2014
A meteorite streaks across the Australian night sky, in front of the Milky Way.
Image credit: Alex Cherney/terrastro.com
Video credit: Alex Cherney/terrastro.com
By Joe Rao, Space.com Skywatching Columnist | March 31, 2014 05:49pm ET
From eclipses and planets to meteor showers galore, the northern spring season of 2014 will bring a number of eye-catching celestial sights for stargazers on Earth.
Weather permitting, some of the best spring night sky events could be readily visible without the aid of binoculars or a telescope, even from brightly-lit cities. But you'll need to know when and where to look to make the most of the season.
I've always felt that many astronomers started their careers as perceptive children who responded to the thrill of witnessing a noteworthy astronomical event. So whether you want to impress a youngster, or you're simply hoping to witness a head-turning astronomical event for yourself, it always helps to be ready in advance by marking your calendar and highlighting a number of these special dates:
April 14 and15: Mars' closest approach in 2014 and a total eclipse of the moon!
During the overnight hours of April 14 and 15, it will be a night for viewing first Mars and later the full moon.
First, Mars will come to within 57.4 million miles (92.4 million kilometers) of our planet, making its closest approach to us since Jan. 3, 2008. All through the night, Mars will resemble a dazzling star shining with a steady fiery-colored tint making it a formidable sight; its brightness will match Sirius, the brightest of all the stars.
As a bonus, later that very same night (actually during the early hours of April 15) North America will have a ringside seat to see a total lunar eclipse when the Full Moon becomes transformed into a mottled reddish ball for 78 minutes as it becomes completely immersed in the shadow of the Earth.
This total lunar eclipse will be the first one widely visible from North America in nearly 3.5 years. The Americas will have the best view of this eclipse, although over the Canadian Maritimes, moonset will intervene near the end of totality. Of special interest is the fact that the moon will appear quite near to the bright star Spica, in the constellation Virgo, during the eclipse. They actually will be in conjunction a couple of hours prior to the onset of totality, but they're still relatively near to each other when the eclipse gets underway.
The year 2014 is packed with amazing night sky events. See the year's most exciting celestial events to mark on your calendar in this Space.com infographic.
Credit: Jennifer Lawinski space.com
Rather favorable circumstances are expected for this year’s Lyrid meteor shower, predicted to be at maximum this morning. The radiant, located near the brilliant bluish-white star Vega, rises in the northeast about the time evening twilight ends, and viewing will improve until light from the last-quarter moon begins to interfere just after 2 a.m. your local time.
Under the best conditions, 10 to 15 members of this shower can be seen in an hour by a single observer. The Lyrids remain about a quarter of their peak number for about two days. These bright meteors are associated with Thatcher’s Comet of 1861.
April 28 and 29: A Ring Eclipse that nobody will see?
It is quite possible that only penguins will witness the annular solar eclipse, also known as a "ring of fire" solar eclipse. That's because it will occur within the uninhabited region of Wilkes Land in Antarctica.
Those living in southernmost parts of Indonesia as well as Australia (where it will be autumn) will at least get a view of a partial eclipse of the sun. Because the axis of the moon's antumbral shadow misses the Earth and only its edge grazes Antarctica, it makes an accurate prediction of the duration of annularity all but impossible.
May 6: The Eta Aquarid meteor shower
The annual Eta Aquarid meteor shower — "shooting stars" spawned by the famed Halley's Comet — is scheduled to reach maximum early this morning. It's usually the year's richest meteor display for Southern Hemisphere observers, but north of the equator the Eta Aquarid shower is one of the more difficult annual displays to observe.
From mid-northern latitudes, the radiant (from where the meteors appear to emanate) rises about 1:30 a.m. local daylight time, scarcely two hours before morning twilight begins to interfere. At peak activity, about a dozen shower members can be seen per hour by a single observer with good sky conditions from latitude 26 degrees North, but practically zero north of latitude 40 degrees. The shower remains active at roughly one-half peak strength for a couple of days before and after the maximum. Conditions this year are excellent; the moon is absent from the predawn sky for more than a week around maximum.
May 10: Saturn at opposition
The ringed planet Saturn reaches opposition; it rises in the east-southeast at dusk, is due south in the middle of the night and sets in the west-southwest at dawn. Once it gains enough altitude, it appears similarly as bright as the zero-magnitude stars Arcturus and Vega.
Saturn's famous rings appear much more impressive than in recent years, since they are now tipped by 21.5 degrees from edge on.
May 24: Possible outburst of bright meteors
Perhaps the most dramatic sky event in 2014 could come at the start of the Memorial Day weekend. In the predawn hours of Saturday, May 24, our planet is expected to sweep through a great number of dusty trails left behind in space by the small comet P/209 LINEAR.
This unusual cosmic interaction might possibly result in an amazing, albeit brief display of meteors — popularly known as "shooting stars" — perhaps numbering in the many dozens …or even hundreds per hour. Nobody knows exactly how many meteors will be seen, but several meteor scientists believe that because the particles will be unusually large, the meteors will be outstandingly bright.
May 25: Mercury attains its greatest elongation
The planet Mercury will reach its greatest elongation, or greatest angular distance, east of the sun on this night. This is Mercury's best evening apparition of the year; it sets about 100 minutes after sunset. An hour after sunset, look low above the west-northwest horizon; the speedy planet should be easily visible as a yellowish "star."
Mercury will appear somewhat brighter up to two weeks before this date, and noticeably dimmer for about a week afterwards.
Joe Rao serves as an instructor and guest lecturer at New York's Hayden Planetarium. He writes about astronomy for Natural History magazine, the Farmer's Almanac and other publications, and he is also an on-camera meteorologist for News 12 Westchester, N.Y. space.com
Pink Planet GJ 504b
Pink Alien Planet Is Smallest Photographed Around Sun-Like Star
by Megan Gannon, News Editor | August 06, 2013 11:32am ET
www.space.com
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Glowing a dark magenta, the newly discovered exoplanet GJ 504b weighs in with about four times Jupiter's mass, making it the lowest-mass planet ever directly imaged around a star like the sun. This image is an artist's representation of the alien world.
Credit: NASA's Goddard Space Flight Center/S. Wiessinger
This composite combines Subaru images of GJ 504 using two near-infrared wavelengths (shown in orange and blue). Once processed to remove scattered starlight, the images reveal the orbiting planet, GJ 504 b.
Credit: NASA’s Goddard Space Flight Center/NOA
by Megan Gannon, News Editor | August 06, 2013 11:32am ET
www.space.com
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Credit: NASA's Goddard Space Flight Center/S. Wiessinger
Astronomers have snapped a photo of a pink alien world that's the smallest yet exoplanet found around a star like our sun.
The alien planet GJ 504b is a colder and bluer world than astronomers had anticipated and it likely has a dark magenta hue, infrared data from the Subaru Telescope in Hawaii revealed.
"If we could travel to this giant planet, we would see a world still glowing from the heat of its formation with a color reminiscent of a dark cherry blossom, a dull magenta," study researcher Michael McElwain, of NASA's Goddard Space Flight Center in Greenbelt, Md., said in a statement from the space agency.
Credit: NASA’s Goddard Space Flight Center/NOA
"Our near-infrared camera reveals that its color is much more blue than other imaged planets, which may indicate that its atmosphere has fewer clouds," McElwain added.
The exoplanet orbits the bright star GJ 504, which is 57 light-years from Earth, slightly hotter than the sun and faintly visible to the naked eye in the constellation Virgo. The star system is relatively young at roughly 160 million years old. (For comparison, Earth's system is 4.5 billion years old).
Though it is the smallest alien world caught on camera around a sun-like star, the gas planet around GJ 504 is still huge — about four times the size of Jupiter. It lies nearly 44 Earth-sun distances from its central star, far beyond the system's habitable zone, and it has an effective temperature of about 460 degrees Fahrenheit (237 Celsius), according to the researchers' estimates.
The exoplanet's features challenge the core-accretion model of planet formation, they study's researchers say. Under this widely accepted theory, asteroid and comet collisions produce a core for Jupiter-like planets and when they gets massive enough, their gravitational pull draws in gas from the gas-rich disk of debris that circles their young star. But this model doesn't explain the formation of planets like GJ 504b that are far away from their parent star.
"This is among the hardest planets to explain in a traditional planet-formation framework," study researcher Markus Janson, a Hubble postdoctoral fellow at Princeton University in New Jersey, said in a statement. "Its discovery implies that we need to seriously consider alternative formation theories, or perhaps to reassess some of the basic assumptions in the core-accretion theory."
The discovery of GJ 504b was part of a larger survey, the Strategic Exploration of Exoplanets and Disks with Subaru or SEEDS program, which seeks to explain how planetary systems come together by looking at star systems of many sizes and ages with images at near-infrared wavelengths.
Direct imaging can help scientists measure an alien planet's luminosity, temperature, atmosphere and orbit, but it's difficult to detect faint planets next to their bright parent stars. The study's leader, Masayuki Kuzuhara of the Tokyo Institute of Technology, said the task is "like trying to take a picture of a firefly near a searchlight."
Two of the Subaru Telescope's tools in particular — the High Contrast Instrument for the Subaru Next Generation Adaptive Optics and the InfraRed Camera and Spectrograph — help scientists tease out light from these faint exoplanet sources.
The study on GJ 504b will be published in The Astrophysical Journal.