Tuesday, September 12, 2017

Tropical Storm Harvey is bringing catastrophic flooding to Houston, Texas

Tropical Storm Harvey is bringing catastrophic flooding to Houston, Texas:

After making landfall on Friday night, Hurricane Harvey has since been downgraded to a tropical storm but it is still wreaking damage throughout southeast Texas. Massive flooding is being reported in the Houston area, thanks to two bands of rain that merged and strengthened on top of the city overnight. In the last 24 hours, Houston and nearby Galveston have received 24 inches of rain, and it looks like it’s not letting up any time soon.

“We’re really dealing with a disaster that’s just now beginning in terms of rainfall and flooding,” Patrick Burke, a lead forecaster with the National Weather Service, tells The Verge. Harvey was an incredibly powerful Category 4 storm when it first hit Texas, and though it weakened after making...

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Catastrophic flooding: all the updates as Harvey makes landfall

Catastrophic flooding: all the updates as Harvey makes landfall:

‘We’re really dealing with a disaster that’s just now beginning’

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Korean astronomers saw a distant explosion 600 years ago — and we just found the stars that caused it

Korean astronomers saw a distant explosion 600 years ago — and we just found the stars that caused it:

In March of 1437, Korean astronomers in Seoul saw what they thought was a new, bright star appear in the night sky. Now, nearly 600 years later, astronomers have figured out what those stargazers actually saw: a thermonuclear explosion caused by the interaction of two distant stars. The new research pinpoints the location of those two stars in the sky, solving a mystery that’s plagued astronomers for decades and providing clues about what happens to pairs of stars centuries after they explode.

The event that the Korean astronomers saw lasted 14 days, leading modern astronomers to suspect it was something known as a classical nova. This is a type of explosion caused by an ordinary star similar to our Sun and a white dwarf — a small,...

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Jupiter's vividly glowing auroras have a mysterious power source

Jupiter's vividly glowing auroras have a mysterious power source:

For the first time ever, NASA’s Juno spacecraft has spotted electrons being fired down into Jupiter’s atmosphere at up to 400,000 volts. That’s an enormous amount of energy that gives rise to the planet’s glowing auroras. These incredibly high voltages, however, are only spotted occasionally — and that’s raising questions about what exactly is behind some of the planet’s most vivid glows at the poles.

The discovery, detailed in a study published today in Nature, was made possible by the instruments on board Juno, which has been orbiting Jupiter for a little over a year, passing by the poles closer than any other spacecraft has before. It confirms, in part, what astronomers expected, but it also shows that Jupiter’s auroras behave...

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Free walkie-talkie app tops App Store charts ahead of Hurricane Irma

Free walkie-talkie app tops App Store charts ahead of Hurricane Irma:

With the Category 5 Hurricane Irma, now one of the strongest hurricanes ever recorded in the Atlantic, on its way toward the Caribbean and possibly the southeastern tip of the US, a little-known walkie-talkie app has shot to the top of Apple’s App Store. The free app, called Zello Walkie Talkie, lets your phone communicate as a two-way radio so long as you have a network or Wi-Fi connection. What makes it useful is that it allows immediate voice communication to others in a shared channel, as opposed to having to place a phone call and hope someone on the other end picks up. The ad-free service can also be used to send texts and photos.

Zello first began rising in the top free chart as Tropical Storm Harvey made landfall in Texas as a...

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Record-breaking Galaxy Five Billion Light-Years Away Shows We Live in Magnetic Universe

Record-breaking Galaxy Five Billion Light-Years Away Shows We Live in Magnetic Universe:

An image obtained using the Hubble Space Telescope showing three objects. The two brightest objects (upper right and lower left) are lensed images of the same, distant quasar. The dimmer object between the two lensed images is the galaxy in which a magnetic field was detected. Image: NASA

A team of astronomers has observed the magnetic field of a galaxy five billion light-years from Earth. The galaxy is the most distant in which a coherent magnetic field has been observed and provides important insight into how magnetism in the Universe formed and evolved.

The observation shows a magnetic field of a similar strength and configuration to that seen in our own Milky Way Galaxy, even though the distant galaxy is five billion years younger than ours. This is evidence that galactic magnetic fields form early in a galaxy’s life and remain relatively stable.

“This finding is exciting,” says Dr. Sui Ann Mao, an astronomer and Minerva Research Group leader at the Max Planck Institute for Radio Astronomy and lead author of the paper describing the observation. “It is now the record holder of the most distant galaxy for which we have this magnetic field information.” The paper was published August 28 in Nature Astronomy.

Galaxies have their own magnetic fields, but they are incredibly weak—a million times weaker than the Earth’s magnetic field. One theory suggests that the magnetic field of a young galaxy starts off weak and tangled, becoming stronger and more organized over time.

But, because the magnetic field of the observed galaxy is not much different from the fields we observe in our own Milky Way Galaxy and nearby galaxies, the detection is evidence that galactic magnetism appears relatively early, rather than growing slowly over time.

“This means that magnetism is generated very early in a galaxy’s life by natural processes, and thus that almost every heavenly body is magnetic,” says Prof. Bryan Gaensler, Dunlap Institute for Astronomy & Astrophysics, University of Toronto, and a co-author of the paper. “The implication is that we need to understand magnetism to understand the Universe.”

Studying the evolution of galactic magnetic fields requires observations of galaxies at different distances from us because such observations show us galaxies at different ages.

But these observations are difficult to make, in part because a magnetic field can’t be detected directly. Instead, we can only detect one by observing the magnetic fingerprint it leaves on light passing through it—an effect referred to as Faraday Rotation.

Mao, Gaensler and their colleagues were able to make their observation because a quasar—a very bright and distant galaxy—lies beyond the galaxy being studied, along the same line of sight. Thanks to this chance alignment, the quasar’s light passes through the galaxy’s magnetic field on its way to us, picking up the tell-tale Faraday Rotation fingerprint.

The observation was made using the Karl G. Jansky Very Large Array, an array of radio telescope dishes in Plains of San Agustin in the New Mexico desert, operated by the National Radio Astronomy Observatory.

“Nobody knows where cosmic magnetism comes from or how it was generated,” says Gaensler. “But now, we have obtained a major clue needed for solving this mystery, by extracting the fossil record of magnetism in a galaxy billions of years before the present day.”

Giant Asteroid to Swoosh by Earth on September 1

Giant Asteroid to Swoosh by Earth on September 1:

Image credit: NASA/JPL-Caltech

A massive asteroid over four kilometers wide is expected to fly by our planet on Friday, September 1. The space rock, designated 1981 ET3 (also known as Florence), will miss the Earth at a safe distance of 18.5 lunar distances (LD), or seven million kilometers.

Detected by Schelte "Bobby" Bus at Siding Spring Observatory in Australia in March 1981, Florence was named in honor of Florence Nightingale (1820-1910), the founder of modern nursing. 

Measurements made by NASA's Spitzer Space Telescope and NEOWISE mission indicate that Florence is about 4.4 kilometers in size, what makes it one of the largest known near-Earth asteroids. It is also the largest object to pass by our planet this close since NASA’s program to detect and track near-Earth asteroids began.

“While many known asteroids have passed by closer to Earth than Florence will on September 1, all of those were estimated to be smaller,” said Paul Chodas, manager of NASA’s Center for Near-Earth Object Studies (CNEOS) at the agency's Jet Propulsion Laboratory in Pasadena, California.

Florence has an absolute magnitude of 14.1 and a rotation period of approximately 2.36 hours. The asteroid has a semimajor axis of about 1.77 AU and orbits the sun every 2.35 years.

The close approach of Florence on September 1 will take place at 12:06 UTC, when it will pass by our planet with a relative velocity of 13.53 km/s. The upcoming fly-by will offer an excellent opportunity to conduct radar observations of this object. Radar imaging is planned at NASA's Goldstone Solar System Radar in California and at the National Science Foundation's Arecibo Observatory in Puerto Rico. These images could show the real size of Florence and could also reveal surface details as small as about 10 meters.

Florence is classified as one of the 1,803 Potentially Hazardous Asteroids (PHAs) currently known. PHAs are asteroids larger than 100 meters that can come closer to Earth than 19.5 LD. None of the known PHAs is on a collision course with our planet.

Lunar Reconnaissance Orbiter Captures Solar Eclipse as Seen From the Moon

Lunar Reconnaissance Orbiter Captures Solar Eclipse as Seen From the Moon:

NASA’s Lunar Reconnaissance Orbiter shows the shadow of the Moon cast on the United States during the Aug. 21, 2017, total solar eclipse. Credits: NASA/GSFC/Arizona State University

During the total solar eclipse on Aug. 21, NASA’s Lunar Reconnaissance Orbiter, or LRO, captured an image of the Moon’s shadow over a large region of the United States, centered just north of Nashville, Tennessee. As LRO crossed the lunar south pole heading north at 3,579 mph (1,600 meters per second), the shadow of the Moon was racing across the United States at 1,500 mph (670 meters per second).

A few minutes later, LRO began a slow 180-degree turn to look back at Earth, capturing an image of the eclipse very near the location where totality lasted the longest. The spacecraft’s Narrow Angle Camera began scanning Earth at 2:25:30 p.m. EDT (18:25:30 UTC) and completed the image 18 seconds later.

The Narrow Angle Camera is part of the Lunar Reconnaissance Orbiter Camera system. Two Narrow Angle Cameras capture high-resolution black and white images, and a third, the Wide Angle Camera, captures moderate-resolution images using filters to provide information about the properties and color of the lunar surface. 

The Narrow Angle Camera builds up an image line by line rather than the more typical “instantaneous” framing that occurs with digital or cell-phone cameras. Each line of the image is exposed for less than one-thousandth of a second; the exposure time was set as low as possible to prevent bright clouds from saturating the sensor. It takes about 18 seconds to acquire all 52,224 lines for the image.

While the thrill of the total eclipse was in experiencing the shadow of the Moon sweep across us on Earth, on the Moon this was just another day. The lunar nearside was one week into its two-week night, while the Sun shone on the far side in the middle of its two-week day. Because solar eclipses do not affect the health or power supply of the spacecraft, LRO operated normally during the total solar eclipse.

Launched on June 18, 2009, LRO has collected a treasure trove of data with its seven powerful instruments, making an invaluable contribution to our knowledge about the Moon and reminding us, through these eclipse images, of the beauty of our Earth. 

LRO is managed by NASA's Goddard Space Flight Center in Greenbelt, Maryland, as a project under NASA's Discovery Program. The Discovery Program is managed by NASA's Marshall Spaceflight Center in Huntsville, Alabama, for the Science Mission Directorate at NASA Headquarters in Washington.

The Lunar Reconnaissance Orbiter Camera was developed at Malin Space Science Systems in San Diego, California and Arizona State University.

Credit: NASA

Weightlessness Affects Health of Astronauts at Molecular Level

Weightlessness Affects Health of Astronauts at Molecular Level:


A team of scientists from Russia and Canada has analyzed the effect of space conditions on the protein composition in blood samples of 18 Russian cosmonauts. The results indicated many significant changes in the human body caused by space flight. These changes are intended to help the body adapt and take place in all the major types of human cells, tissues, and organs. The results of the research have been published in the prestigious scientific journal Nature Scientific Reports. Skoltech and MIPT Professor Evgeny Nikolaev initiated this research, and he is a corresponding author of the study.

The effects of spaceflight on the human body have been studied actively since the mid-20th century. It is widely known that space conditions influence metabolism, thermoregulation, heart biorhythms, muscle tonus, the respiration system and other physiological aspects of the human body function. However, the molecular mechanisms which drive the physiological changes caused by space flights remain unknown.

Proteins are key players in the adaptive processes in an organism, so the scientists decided to focus on them. To gain a deeper understanding of the changes in human physiology during space travel, the research team quantified concentrations of 125 proteins in the blood plasma of 18 Russian cosmonauts who had been on long-duration missions to the International Space Station. The blood was initially taken from them 30 days prior to their flights, and again immediately after their return to Earth and finally seven days after that. This timing was chosen as it helped the scientists to identify trends in protein concentration changes and see how fast the protein concentrations returned to their normal levels prior to the flight.

Protein concentrations were measured using a mass spectrometer. This technology makes it possible to identify a particular molecule and perform a quantitative analysis of a mixture of substances (count the exact number of molecules).

As a result of the study, the scientists found proteins whose concentrations remained unchanged, as well as those whose concentrations did change, but recovered rapidly to their pre-flight levels and those whose levels recovered very slowly after the cosmonaut's return to Earth.

“For the research, we took a set of proteins – non-infectious diseases biomarkers. The results showed that in weightlessness, the immune system acts like it does when the body is infected because the human body doesn’t know what to do and tries to turn on all possible defense systems. For this study, we began by using quantitative proteomics to study the cosmonauts’ blood indicators, so we detected not only the presence of a protein but its amount as well. We plan to use a targeted approach in the future to detect more specific proteins responsible for the human response to space conditions. To do this, the cosmonauts will have to take blood tests while in orbit,” said Professor Nikolaev.

The factors that affect the human body during spaceflight are very interesting because they are different to those that influenced human evolution on Earth. It is not known if the human body has mechanisms responsible for rapidly adapting to such major changes. The results of the study indicate that such mechanisms probably do not exist because, during space flight, these adaptations take place in all the major types of human cells, tissues, and organs. This indicates that the human body does not know what to do and is trying to do everything in its power.

Credit: mipt.ru

Artificial Intelligence Analyzes Gravitational Lenses 10 Million Times Faster

Artificial Intelligence Analyzes Gravitational Lenses 10 Million Times Faster:

KIPAC scientists have for the first time used artificial neural networks to analyze complex distortions in spacetime, called gravitational lenses, demonstrating that the method is 10 million times faster than traditional analyses. (Greg Stewart/SLAC National Accelerator Laboratory)

Researchers from the Department of Energy’s SLAC National Accelerator Laboratory and Stanford University have for the first time shown that neural networks – a form of artificial intelligence – can accurately analyze the complex distortions in spacetime known as gravitational lenses 10 million times faster than traditional methods.

“Analyses that typically take weeks to months to complete, that require the input of experts and that are computationally demanding, can be done by neural nets within a fraction of a second, in a fully automated way and, in principle, on a cell phone’s computer chip,” said postdoctoral fellow Laurence Perreault Levasseur, a co-author of a study published today in Nature.

The team at the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC), a joint institute of SLAC and Stanford, used neural networks to analyze images of strong gravitational lensing, where the image of a faraway galaxy is multiplied and distorted into rings and arcs by the gravity of a massive object, such as a galaxy cluster, that’s closer to us. The distortions provide important clues about how mass is distributed in space and how that distribution changes over time – properties linked to invisible dark matter that makes up 85 percent of all matter in the universe and to dark energy that’s accelerating the expansion of the universe.

Until now this type of analysis has been a tedious process that involves comparing actual images of lenses with a large number of computer simulations of mathematical lensing models. This can take weeks to months for a single lens.

But with the neural networks, the researchers were able to do the same analysis in a few seconds, which they demonstrated using real images from NASA’s Hubble Space Telescope and simulated ones.

To train the neural networks in what to look for, the researchers showed them about half a million simulated images of gravitational lenses for about a day. Once trained, the networks were able to analyze new lenses almost instantaneously with a precision that was comparable to traditional analysis methods. In a separate paper, submitted to The Astrophysical Journal Letters, the team reports how these networks can also determine the uncertainties of their analyses.

“The neural networks we tested – three publicly available neural nets and one that we developed ourselves – were able to determine the properties of each lens, including how its mass was distributed and how much it magnified the image of the background galaxy,” said the study’s lead author Yashar Hezaveh, a NASA Hubble postdoctoral fellow at KIPAC.

This goes far beyond recent applications of neural networks in astrophysics, which were limited to solving classification problems, such as determining whether an image shows a gravitational lens or not.

The ability to sift through large amounts of data and perform complex analyses very quickly and in a fully automated fashion could transform astrophysics in a way that is much needed for future sky surveys that will look deeper into the universe – and produce more data – than ever before.

The Large Synoptic Survey Telescope (LSST), for example, whose 3.2-gigapixel camera is currently under construction at SLAC, will provide unparalleled views of the universe and is expected to increase the number of known strong gravitational lenses from a few hundred today to tens of thousands.

“We won’t have enough people to analyze all these data in a timely manner with the traditional methods,” Perreault Levasseur said. “Neural networks will help us identify interesting objects and analyze them quickly. This will give us more time to ask the right questions about the universe.”

Neural networks are inspired by the architecture of the human brain, in which a dense network of neurons quickly processes and analyzes information.

In the artificial version, the “neurons” are single computational units that are associated with the pixels of the image being analyzed. The neurons are organized into layers, up to hundreds of layers deep. Each layer searches for features in the image. Once the first layer has found a certain feature, it transmits the information to the next layer, which then searches for another feature within that feature, and so on.

“The amazing thing is that neural networks learn by themselves what features to look for,” said KIPAC staff scientist Phil Marshall, a co-author of the paper. “This is comparable to the way small children learn to recognize objects. You don’t tell them exactly what a dog is; you just show them pictures of dogs.”

But in this case, Hezaveh said, “It’s as if they not only picked photos of dogs from a pile of photos, but also returned information about the dogs’ weight, height and age.”

Although the KIPAC scientists ran their tests on the Sherlock high-performance computing cluster at the Stanford Research Computing Center, they could have done their computations on a laptop or even on a cell phone, they said. In fact, one of the neural networks they tested was designed to work on iPhones.

“Neural nets have been applied to astrophysical problems in the past with mixed outcomes,” said KIPAC faculty member Roger Blandford, who was not a co-author on the paper. “But new algorithms combined with modern graphics processing units, or GPUs, can produce extremely fast and reliable results, as the gravitational lens problem tackled in this paper dramatically demonstrates. There is considerable optimism that this will become the approach of choice for many more data processing and analysis problems in astrophysics and other fields.”

ALMA Finds Huge Hidden Reservoirs of Turbulent Gas in Distant Galaxies

ALMA Finds Huge Hidden Reservoirs of Turbulent Gas in Distant Galaxies:

This cartoon shows how gas falling into distant starburst galaxies ends up in vast turbulent reservoirs of cool gas extending 30 000 light-years from the central regions. ALMA has been used to detect these turbulent reservoirs of cold gas surrounding similar distant starburst galaxies. By detecting CH+ for the first time in the distant Universe, this research opens up a new window of exploration into a critical epoch of star formation.  Credit: ESO/L. Benassi

ALMA has been used to detect turbulent reservoirs of cold gas surrounding distant starburst galaxies. By detecting CH+ for the first time in the distant Universe this research opens up a new window of exploration into a critical epoch of star formation. The presence of this molecule sheds new light on how galaxies manage to extend their period of rapid star formation. The results appear in the journal Nature.

A team led by Edith Falgarone (Ecole Normale Supérieure and Observatoire de Paris, France) has used the Atacama Large Millimeter/submillimeter Array (ALMA) to detect signatures of the carbon hydride molecule CH+ in distant starburst galaxies. The group identified strong signals of CH+ in five out of the six galaxies studied, including the Cosmic Eyelash (eso1012). This research provides new information that helps astronomers understand the growth of galaxies and how a galaxy’s surroundings fuel star formation.

“CH+ is a special molecule. It needs a lot of energy to form and is very reactive, which means its lifetime is very short and it can’t be transported far. CH+ therefore traces how energy flows in the galaxies and their surroundings,” said Martin Zwaan, an astronomer at ESO, who contributed to the paper.

How CH+ traces energy can be thought of by analogy to being on a boat in a tropical ocean on a dark, moonless night. When the conditions are right, fluorescent plankton can light up around the boat as it sails. The turbulence caused by the boat sliding through the water excites the plankton to emit light, which reveals the existence of the the turbulent regions in the underlying dark water. Since CH+ forms exclusively in small areas where turbulent motions of gas dissipates, its detection in essence traces energy on a galactic scale.

The observed CH+ reveals dense shock waves, powered by hot, fast galactic winds originating inside the galaxies’ star forming regions. These winds flow through a galaxy, and push material out of it, but their turbulent motions are such that part of the material can be re-captured by the gravitational pull of the galaxy itself. This material gathers into huge turbulent reservoirs of cool, low-density gas, extending more than 30 000 light-years from the galaxy’s star forming region.

“With CH+, we learn that energy is stored within vast galaxy-sized winds and ends up as turbulent motions in previously unseen reservoirs of cold gas surrounding the galaxy,” said Falgarone, who is lead author of the new paper. “Our results challenge the theory of galaxy evolution. By driving turbulence in the reservoirs, these galactic winds extend the starburst phase instead of quenching it.”

The team determined that galactic winds alone could not replenish the newly revealed gaseous reservoirs and suggests that the mass is provided by galactic mergers or accretion from hidden streams of gas, as predicted by current theory.

“This discovery represents a major step forward in our understanding of how the inflow of material is regulated around the most intense starburst galaxies in the early Universe,” says ESO’s Director for Science, Rob Ivison, a co-author on the paper. “It shows what can be achieved when scientists from a variety of disciplines come together to exploit the capabilities of the world's most powerful telescope.”

Credit: ESO

Heavy Stellar Traffic, Deflected Comets, and a Closer Look at the Triggers of Cosmic Disaster

Heavy Stellar Traffic, Deflected Comets, and a Closer Look at the Triggers of Cosmic Disaster:

Image of the Comet C/2012 S1 (ISON), taken with the TRAPPIST–South national telescope at ESO's La Silla Observatory on the morning of Friday 15 November 2013, whose likely origin is the Oort cloud. This comet is definitely not colliding with Earth, but it shows the typical appearance of comets entering the inner solar system, including the typical tail made of gas and dust. Image: TRAPPIST/E. Jehin/ESO

As stars pass close by our solar system, they can nudge comets from the distant Oort cloud into the inner regions around the Sun. Thus, stellar encounters are an important factor in determining the risk of large cosmic impacts on Earth. Now, Coryn Bailer-Jones from the Max Planck Institute for Astronomy has used data from the ESA satellite Gaia to give the first systematic estimate of the rate of such close stellar encounters. Every million years, up to two dozen stars pass within a few light-years of the Sun, making for a near-constant state of perturbation. The results have been published in the journal Astronomy & Astrophysics.

Comets colliding with Earth are among the more violent and extensive cosmic catastrophes that can befall our home planet. The best known such impact is the one which, 66 million years ago, caused or at least hastened the demise of the dinosaurs (although it is not known whether the blame in this case falls on a comet or an asteroid).

It must be said that, to the best of current knowledge, impacts with regional or even global consequences are exceedingly rare, and occur at a rate of no more than one per million years. Also, monitoring systems give us a fairly complete inventory of larger asteroids and comets, none of which is currently on a collision course with Earth.

Still, the consequences are serious enough that studies of the causes of comet impacts are not purely academic. The prime culprits are stellar encounters: stars passing through our Sun's cosmic neighborhood. The outskirts of our solar system are believed to host a reservoir of cold and icy objects – potential comets – known as the Oort cloud. The gravitational influence of passing stars can nudge these comets inwards, and some will begin a journey all the way to the inner solar system, possibly on a collision course with Earth. That is why knowledge of these stellar encounters and their properties has a direct impact on risk assessment for comet impacts.

Now, Bailer-Jones has published the first systematic estimate of the rate of such stellar encounters. The new result uses data from the first data release (DR1) of the Gaia mission that combines new Gaia measurements with older measurements by ESA's Hipparcos satellite. Crucially, Bailer-Jones modeled each candidate for a close encounter as a swarm of virtual stars, showing how uncertainties in the orbital data will influence the derived rate of encounters.

Bailer-Jones found that within a typical million years, between 490 and 600 stars will pass the Sun within a distance of 16.3 light-years (5 parsecs, to use a unit more common in professional astronomy) or less. Between 19 and 24 stars will pass at 3.26 light-years (1 parsec) or less. All these hundreds of stars would be sufficiently close to nudge comets from the Oort cloud into the solar system. The new results are in the same ballpark as earlier, less systematic estimates that show that when it comes to stellar encounters, traffic in our cosmic neighborhood is rather heavy.

The current results are valid for a period of time that reaches about 5 million years into the past and into the future. With Gaia's next data release, DR2 slated for April 2018, this could be extended to 25 million years each way. However, astronomers intending to go even further and search for the stars that might be responsible for hurling a comet towards the dinosaurs will need to know our home galaxy and its mass distribution in much more detail than we currently do – a long-term goal of the researchers involved in Gaia and related projects.

Credit: mpia.de

Physicists Propose New Theories of Black Holes from the Very Early Universe

Physicists Propose New Theories of Black Holes from the Very Early Universe:

Image credit: den-belitsky/iStock

UCLA physicists have proposed new theories for how the universe’s first black holes might have formed and the role they might play in the production of heavy elements such as gold, platinum and uranium. Two papers on their work were published in the journal Physical Review Letters.

A long-standing question in astrophysics is whether the universe’s very first black holes came into existence less than a second after the Big Bang or whether they formed only millions of years later during the deaths of the earliest stars.

Alexander Kusenko, a UCLA professor of physics, and Eric Cotner, a UCLA graduate student, developed a compellingly simple new theory suggesting that black holes could have formed very shortly after the Big Bang, long before stars began to shine. Astronomers have previously suggested that these so-called primordial black holes could account for all or some of the universe’s mysterious dark matter and that they might have seeded the formation of supermassive black holes that exist at the centers of galaxies. The new theory proposes that primordial black holes might help create many of the heavier elements found in nature.

The researchers began by considering that a uniform field of energy pervaded the universe shortly after the Big Bang. Scientists expect that such fields existed in the distant past. After the universe rapidly expanded, this energy field would have separated into clumps. Gravity would cause these clumps to attract one another and merge together. The UCLA researchers proposed that some small fraction of these growing clumps became dense enough to become black holes.

Their hypothesis is fairly generic, Kusenko said, and it doesn’t rely on what he called the “unlikely coincidences” that underpin other theories explaining primordial black holes.

The paper suggests that it’s possible to search for these primordial black holes using astronomical observations. One method involves measuring the very tiny changes in a star’s brightness that result from the gravitational effects of a primordial black hole passing between Earth and that star. Earlier this year, U.S. and Japanese astronomers published a paper on their discovery of one star in a nearby galaxy that brightened and dimmed precisely as if a primordial black hole was passing in front of it.

In a separate study, Kusenko, Volodymyr Takhistov, a UCLA postdoctoral researcher, and George Fuller, a professor at UC San Diego, proposed that primordial black holes might play an important role in the formation of heavy elements such as gold, silver, platinum and uranium, which could be ongoing in our galaxy and others.

The origin of those heavy elements has long been a mystery to researchers.

“Scientists know that these heavy elements exist, but they’re not sure where these elements are being formed,” Kusenko said. “This has been really embarrassing.”

The UCLA research suggests that a primordial black hole occasionally collides with a neutron star — the city-sized, spinning remnant of a star that remains after some supernova explosions — and sinks into its depths.

When that happens, Kusenko said, the primordial black hole consumes the neutron star from the inside, a process that takes about 10,000 years. As the neutron star shrinks, it spins even faster, eventually causing small fragments to detach and fly off. Those fragments of neutron-rich material may be the sites in which neutrons fuse into heavier and heavier elements, Kusenko said.

However, the probability of a neutron star capturing a black hole is rather low, said Kusenko, which is consistent with observations of only some galaxies being enriched in heavy elements. The theory that primordial black holes collide with neutron stars to create heavy elements also explains the observed lack of neutron stars in the center of the Milky Way galaxy, a long-standing mystery in astrophysics.

This winter, Kusenko and his colleagues will collaborate with scientists at Princeton University on computer simulations of the heavy elements produced by a neutron star–black hole interaction. By comparing the results of those simulations with observations of heavy elements in nearby galaxies, the researchers hope to determine whether primordial black holes are indeed responsible for Earth’s gold, platinum and uranium.

Credit: ucla.edu

Hubble Delivers First Hints of Possible Water Content of TRAPPIST-1 Planets

Hubble Delivers First Hints of Possible Water Content of TRAPPIST-1 Planets:

This artist’s impression shows the view from the surface of one of the planets in the TRAPPIST-1 system. At least seven planets orbit this ultracool dwarf star 40 light-years from Earth and they are all roughly the same size as the Earth. Several of the planets are at the right distances from their star for liquid water to exist on the surfaces.  This artist’s impression is based on the known physical parameters of the planets and stars seen, and uses a vast database of objects in the Universe.  Credit: ESO/N. Bartmann/spaceengine.org

An international team of astronomers used the NASA/ESA Hubble Space Telescope to estimate whether there might be water on the seven earth-sized planets orbiting the nearby dwarf star TRAPPIST-1. The results suggest that the outer planets of the system might still harbor substantial amounts of water. This includes the three planets within the habitable zone of the star, lending further weight to the possibility that they may indeed be habitable.

On 22 February 2017 astronomers announced the discovery of seven Earth-sized planets orbiting the ultracool dwarf star TRAPPIST-1, 40 light-years away. This makes TRAPPIST-1 the planetary system with the largest number of Earth-sized planets discovered so far.

Following up on the discovery, an international team of scientists led by the Swiss astronomer Vincent Bourrier from the Observatoire de l’Université de Genève, used the Space Telescope Imaging Spectrograph (STIS) on the NASA/ESA Hubble Space Telescope to study the amount of ultraviolet radiation received by the individual planets of the system. “Ultraviolet radiation is an important factor in the atmospheric evolution of planets,” explains Bourrier. “As in our own atmosphere, where ultraviolet sunlight breaks molecules apart, ultraviolet starlight can break water vapor in the atmospheres of exoplanets into hydrogen and oxygen.”

While lower-energy ultraviolet radiation breaks up water molecules — a process called photodissociation — ultraviolet rays with more energy (XUV radiation) and X-rays heat the upper atmosphere of a planet, which allows the products of photodissociation, hydrogen and oxygen, to escape.

As it is very light, hydrogen gas can escape the exoplanets’ atmospheres and be detected around the exoplanets with Hubble, acting as a possible indicator of atmospheric water vapor. The observed amount of ultraviolet radiation emitted by TRAPPIST-1 indeed suggests that the planets could have lost gigantic amounts of water over the course of their history.

This is especially true for the innermost two planets of the system, TRAPPIST-1b and TRAPPIST-1c, which receive the largest amount of ultraviolet energy. “Our results indicate that atmospheric escape may play an important role in the evolution of these planets,” summarizes Julien de Wit, from MIT, USA, co-author of the study.

The inner planets could have lost more than 20 Earth-oceans-worth of water during the last eight billion years. However, the outer planets of the system — including the planets e, f and g which are in the habitable zone — should have lost much less water, suggesting that they could have retained some on their surfaces. The calculated water loss rates as well as geophysical water release rates also favor the idea that the outermost, more massive planets retain their water. However, with the currently available data and telescopes no final conclusion can be drawn on the water content of the planets orbiting TRAPPIST-1.

“While our results suggest that the outer planets are the best candidates to search for water with the upcoming James Webb Space Telescope, they also highlight the need for theoretical studies and complementary observations at all wavelengths to determine the nature of the TRAPPIST-1 planets and their potential habitability,” concludes Bourrier.

FINESSE Mission to Investigate Atmospheres of Hundreds of Alien Worlds

FINESSE Mission to Investigate Atmospheres of Hundreds of Alien Worlds:

Artist's concept of the FINESSE spacecraft. Image Credit: JPL

One of NASA’s proposed missions, known as the Fast INfrared Exoplanet Spectroscopy Survey Explorer (FINESSE) could greatly improve our understanding of extrasolar worlds. If selected for development, the spacecraft will investigate at least 500 exoplanet atmospheres, providing detailed information about climate processes on distant alien planets.

FINESSE has been recently chosen by NASA for concept studies and evaluations. It is one of the agency’s six astrophysics Explorers Program proposals that could be selected by 2019 to proceed with construction and launch.

The mission’s main objective is to study the processes that govern planet formation and global climate. It will investigate the mechanisms that establish atmospheric chemical composition and shape atmospheric evolution.

“FINESSE will spectroscopically observe the atmospheres of many hundreds of transiting exoplanets to measure their molecular abundances and thermal profiles,” Robert Zellem, FINESSE science team member at NASA’s Jet Propulsion Laboratory (JPL), told Astrowatch.net.

In order to conduct the planned studies, FINESSE will use the transit method. It will measure how a planet’s atmosphere absorbs light from its host star as a function of wavelength. This will allow to infer the molecules in the planet’s atmosphere.

“By doing this for hundreds of planets, FINESSE will determine how planets form and the crucial factors that establish planetary climate,” Zellem said.

These observations will require a proper imaging system. That is why the FINESSE spacecraft will be equipped in a telescope with a 75-centimeter (29.5-inch) primary mirror and a spectrometer that will observe planets in the visible and infrared wavelengths (from 0.5 to 5 microns).

According to Zellem, wide spectral coverage will enable FINESSE to measure the abundances of molecules such as water, methane, carbon dioxide, and carbon monoxide as well as look for the presence of clouds and hazes.

Data collected by the spacecraft are expected to provide important information that could improve our knowledge about various exoplanets, from rocky terrestrial planets to gas giants like Jupiter. FINESSE could help us discover what these alien worlds are like, determining what makes them they way they are, and allowing this knowledge to be applied in the broader planetary context, including the search for life outside of our Solar System.

If selected for the development, FINESSE is targeted for the launch around 2023. Zellem hopes that during its operational lifetime of two years it will carry out important observations of even more than 1,000 extrasolar worlds.

“FINESSE has the capability in its two year mission to observe the atmospheres of over 1000 transiting exoplanets,” he concluded.

Small Asteroid 2017 QB35 Flies by Earth

Small Asteroid 2017 QB35 Flies by Earth:


A newly spotted asteroid, designated 2017 QB35, flew by Earth on Sunday, September 3, missing our planet at a distance of 0.93 lunar distances (LD), or 345,600 kilometers. The space rock flew by Earth at 8:40 UTC with a relative velocity of 4.1 km/s.

2017 QB35 was discovered on August 31, 2017 by the Mount Lemmon Survey (MLS), which uses a 1.52 m cassegrain reflector telescope at Mount Lemmon Observatory in Arizona. MLS is one of the most prolific surveys when it comes to discovering new NEOs. It has detected more than 50,000 minor planets to date.

2017 QB35 is an Aten-type asteroid with and an absolute magnitude of 29.3 and an estimated diameter between 2 and 8 meters. The object has a semimajor axis of 0.93 AU and an orbital period of 326 days.

Next close approach of 2017 QB35 will occur on June 4, 2025, when it will pass by our planet at a much larger distance of about 100 LD.

Currently, there are 1,803 Potentially Hazardous Asteroids (PHAs) detected, however none of them is on a collision course with our planet. PHAs are asteroids larger than 100 meters that can come closer to Earth than 19.5 LD.

Stellar Corpse Sheds Light on Origin of Cosmic Rays

Stellar Corpse Sheds Light on Origin of Cosmic Rays:

This composite image of the Crab Nebula was assembled with arbitrary color scaling by combining data from five telescopes spanning nearly the entire electromagnetic spectrum. (Image credits: NASA, ESA, NRAO/AUI/NSF and G. Dubner/University of Buenos Aires)

The origin of cosmic rays, high-energy particles from outer space unceasingly impinging on Earth, is among the most challenging open questions in astrophysics. Discovered more than 100 years ago and considered a potential health risk to airplane crews and astronauts, cosmic rays are believed to be produced by shock waves — for example, those resulting from supernovae explosions. The most energetic cosmic rays streaking across the universe carry 10 to 100 million times the energy generated by particle colliders such as the Large Hadron Collider at CERN. New research published in the Monthly Notices of the Royal Astronomical Society sheds new light on the origin of those energetic particles.

"The new result represents a significant advance in our understanding of particle acceleration at shock waves, traditionally regarded as the main sources of energetic particles in the universe," said the study's lead author, Federico Fraschetti, a staff scientist at the University of Arizona's Departments of Planetary Sciences and Astronomy.

The Crab Nebula, remnant of a supernova explosion that was observed almost 1,000 years ago, is one of the best studied objects in the history of astronomy and a known source of cosmic rays. It emits radiation across the entire electromagnetic spectrum, from gamma rays, ultraviolet and visible light, to infrared and radio waves. 

"Most of what we observe comes from very energetic particles such as electrons that did not yet leave the source," said Fraschetti. "Since we can only observe the electromagnetic radiation that they emit from the source itself, we rely on models to reproduce the radiation spectrum we see from the nebula."

The new study, co-authored by Martin Pohl at the University of Potsdam, Germany, revealed that the entire zoo of electromagnetic radiation streaming from the Crab Nebula can arise from a single population of electrons, previously deemed impossible, and that they originate in a different way than scientists have traditionally thought. 

According to the generally accepted model, once the particles reach the shock, they bounce back and forth many times due to the magnetic turbulence. During this process they gain energy — in a similar way to a tennis ball being bounced between two rackets that are steadily moving nearer to each other — and are pushed closer and closer to the speed of light. Such a model follows an idea introduced by Italian physicist Enrico Fermi in 1949.

"The current models do not include what happens when the particles reach their highest energy," said Federico Fraschetti. "Only if we include a different process of acceleration can we explain the entire electromagnetic spectrum we see, and that tells us that while the shock wave still is the source of the acceleration of the particles, the mechanisms must be different."

At the heart of the Crab Nebula lies a pulsar, a rapidly rotating neutron star originating from the explosion of a star a few times more massive than the sun. When it exploded, the star shredded its outer layers, creating the stunning colorscape that makes the Crab Nebula so popular with professional and amateur astronomers. The pulsar emits a wind of electrons and positrons traveling at what astrophysicists call relativistic speed — close to the speed of light. 

"Those particles are the fastest things in the universe," Fraschetti said. "Anything we experience in our everyday lives is very far from relativistic effects. But these highly energetic particles still need to be accelerated even more to produce the electromagnetic radiation that we see coming from the Crab Nebula."

That acceleration, scientists believe, happens at a boundary called the termination shock, where the particle wind slams into the cloud of gas and dust that the star blew off into space when it went supernova. 

Except that just when the particles become energetic enough to leave the system and become cosmic radiation, they go beyond the limits of the models traditionally used to account for the origin of cosmic radiation, Fraschetti and Pohl found. The authors conclude that a better understanding is needed of how particles are accelerated in cosmic sources, and how the acceleration works when the energy of the particles become very large.

Several NASA missions, including ACE, STEREO and WIND, are dedicated to studying the effects of shocks caused by plasma explosions on the surface of the sun as they travel to Earth. Scientists hope that results from those experiments may shed light on the mechanisms of acceleration in objects such as the Crab Nebula.

Credit: arizona.edu

Jupiter’s Aurora Presents a Powerful Mystery

Jupiter’s Aurora Presents a Powerful Mystery:

This image, created with data from Juno’s Ultraviolet Imaging Spectrograph, marks the path of Juno’s readings of Jupiter’s aurora, highlighting the electron measurements that show the discovery of the so-called discrete auroral acceleration processes indicated by the “inverted Vs” in the lower panel. Credits: NASA/JPL-Caltech/SwRI/Randy Gladstone

Scientists on NASA’s Juno mission have observed massive amounts of energy swirling over Jupiter’s polar regions that contribute to the giant planet’s powerful aurora – only not in ways the researchers expected.

Examining data collected by the ultraviolet spectrograph and energetic-particle detector instruments aboard the Jupiter-orbiting Juno spacecraft, a team led by Barry Mauk of the Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, observed signatures of powerful electric potentials, aligned with Jupiter’s magnetic field, that accelerate electrons toward the Jovian atmosphere at energies up to 400,000 electron volts. This is 10 to 30 times higher than the largest auroral potentials observed at Earth, where only several thousands of volts are typically needed to generate the most intense aurora -- known as discrete aurora -- the dazzling, twisting, snake-like northern and southern lights seen in places like Alaska and Canada, northern Europe, and many other northern and southern polar regions.

Jupiter has the most powerful aurora in the solar system, so the team was not surprised that electric potentials play a role in their generation. What’s puzzling the researchers, Mauk said, is that despite the magnitudes of these potentials at Jupiter, they are observed only sometimes and are not the source of the most intense auroras, as they are at Earth.

“At Jupiter, the brightest auroras are caused by some kind of turbulent acceleration process that we do not understand very well,” said Mauk, who leads the investigation team for the APL-built Jupiter Energetic Particle Detector Instrument (JEDI). “There are hints in our latest data indicating that as the power density of the auroral generation becomes stronger and stronger, the process becomes unstable and a new acceleration process takes over. But we’ll have to keep looking at the data.”

Scientists consider Jupiter to be a physics lab of sorts for worlds beyond our solar system, saying the ability of Jupiter to accelerate charged particles to immense energies has implications for how more distant astrophysical systems accelerate particles. But what they learn about the forces driving Jupiter’s aurora and shaping its space weather environment also has practical implications in our own planetary backyard.

“The highest energies that we are observing within Jupiter’s auroral regions are formidable. These energetic particles that create the aurora are part of the story in understanding Jupiter’s radiation belts, which pose such a challenge to Juno and to upcoming spacecraft missions to Jupiter under development,” said Mauk. “Engineering around the debilitating effects of radiation has always been a challenge to spacecraft engineers for missions at Earth and elsewhere in the solar system. What we learn here, and from spacecraft like NASA’s Van Allen Probes and Magnetospheric Multiscale mission (MMS) that are exploring Earth’s magnetosphere, will teach us a lot about space weather and protecting spacecraft and astronauts in harsh space environments. Comparing the processes at Jupiter and Earth is incredibly valuable in testing our ideas of how planetary physics works.” 

Mauk and colleagues present their findings in the Sept. 7 issue of the journal Nature.

NASA’s Jet Propulsion Laboratory, Pasadena, California, manages the Juno mission for the principal investigator, Scott Bolton, of the Southwest Research Institute in San Antonio. Juno is part of NASA’s New Frontiers Program, which is managed at NASA’s Marshall Space Flight Center in Huntsville, Alabama, for NASA’s Science Mission Directorate. Lockheed Martin Space Systems, Denver, built the spacecraft.

Credit: NASA

X-rays Reveal Temperament of Possible Planet-hosting Stars

X-rays Reveal Temperament of Possible Planet-hosting Stars:

GJ 176: A Sun-like Star More than a Billion Years Old Credits: X-ray: NASA/CXC/Queens Univ. of Belfast/R. Booth, et al.; Illustration: NASA/CXC/M. Weiss

A new X-ray study has revealed that stars like the Sun and their less massive cousins calm down surprisingly quickly after a turbulent youth. This result has positive implications for the long-term habitability of planets orbiting such stars.

A team of researchers used data from NASA’s Chandra X-ray Observatory and ESA’s XMM-Newton to see how the X-ray brightness of stars similar to the Sun behaves over time. The X-ray emission from a star comes from a thin, hot, outer layer, called the corona. From studies of solar X-ray emission, astronomers have determined that the corona is heated by processes related to the interplay of turbulent motions and magnetic fields in the outer layers of a star.

High levels of magnetic activity can produce bright X-rays and ultraviolet light from stellar flares. Strong magnetic activity can also generate powerful eruptions of material from the star’s surface. Such energetic radiation and eruptions can impact planets and could damage or destroy their atmospheres, as pointed out in previous studies, including Chandra work reported in 2011 and 2013.

Since stellar X-rays mirror magnetic activity, X-ray observations can tell astronomers about the high-energy environment around the star. The new study uses X-ray data from Chandra and XMM-Newton to show that stars like the Sun and their less massive cousins decrease in X-ray brightness surprisingly quickly.

Specifically, the researchers examined 24 stars that have masses similar to the Sun or less, and ages of a billion years or older. (For context, the Sun is 4.5 billion years old.) The rapid observed decline in X-ray brightness implies a rapid decline in energetic activity, which may provide a hospitable environment for the formation and evolution of life on any orbiting planets.

“This is good news for the future habitability of planets orbiting Sun-like stars, because the amount of harmful X-rays and ultraviolet radiation striking these worlds from stellar flares would be less than we used to think,” said Rachel Booth, a graduate student at Queen’s University in Belfast, UK, who led the study.

This result is different from other recent work on Sun-like and lower mass stars with ages less than a billion years. The new work shows that older stars drop in activity far more quickly than their younger counterparts.

“We’ve heard a lot about the volatility of stars less massive than the Sun, like TRAPPIST-1 and Proxima Centauri, and how that’s bad for life-supporting atmospheres on their planets,” said Katja Poppenhaeger, a co-author from Queen’s University and the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass. “It’s refreshing to have some good news to share about potential habitability.”

To understand how quickly stellar magnetic activity level changes over time, astronomers need accurate ages for many different stars. This is a difficult task, but new precise age estimates have recently become available from studies of the way that a star pulsates using NASA’s Kepler and ESA’s CoRoT missions. These new age estimates were used for most of the 24 stars studied here.

Astronomers have observed that most stars are very magnetically active when they are young, since the stars are rapidly rotating. As the rotating star loses energy over time, the star spins more slowly and the magnetic activity level, along with the associated X-ray emission, drops.

“We’re not exactly sure why older stars settle down relatively quickly,” said co-author Chris Watson of Queen’s University. “However, we know it’s led to the successful formation of life in at least one case – around our own Sun.”

One possibility is that the decrease in rate of spin of the older stars occurs more quickly than it does for the younger stars. Another possibility is that the X-ray brightness declines more quickly with time for older, more slowly rotating stars than it does for younger stars.

A paper describing these results has been accepted for publication in the Monthly Notices of the Royal Astronomical Society, and is available online. The other co-authors are Victor Silva Aguirre from Aarhus University in Denmark and Scott Wolk from CfA.

NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra’s science and flight operations.

Credit: NASA

Earth as Hybrid Planet: New Classification Scheme Places Anthropocene Era in Astrobiological Context

Earth as Hybrid Planet: New Classification Scheme Places Anthropocene Era in Astrobiological Context:


For decades, as astronomers have imagined advanced extraterrestrial civilizations, they categorized such worlds by the amount of energy their inhabitants might conceivably be able to harness and use. They sorted the hypothetical worlds into three types according to a scheme named in 1964 for Soviet astronomer Nikolai Kardashev. A Type 1 civilization could manipulate all the energy resources of its home planet (a distant goal yet for Earth) and Type 2 all the energy in its star/planetary system. A super-advanced Type 3 civilization would command the energy of its whole home galaxy. The Kardashev Scale has since become a sort of gold standard for dreaming about possible civilizations beyond Earth.

Now, a team of researchers including Marina Alberti of the University of Washington has devised a new classification scheme for the evolutionary stages of worlds based on “non-equilibrium thermodynamics” — a planet’s energy flow being out of synch, as the presence of life could cause. The categories range from imagined planets with no atmosphere whatsoever to those with an “agency-dominated biosphere” or even a “technosphere,” reflecting the achievements of a vastly advanced, “energy-intensive technological species.”

Their paper, “Earth as a Hybrid Planet: The Anthropocene in an Evolutionary Astrobiological Context,” was published Sept. 6 in the journal Anthropocene. Lead author is Adam Frank, professor of physics and astronomy at the University of Rochester. Alberti is a professor of urban design and planning in the UW College of Built Environments, and director of the college’s Urban Ecology Research Lab.

The new classification system, the researchers say, is a way of thinking about sustainability on a planetary scale in what is being recognized as the Anthropocene epoch — the geological period of humanity’s significant impact on Earth and its ecosystems. Alberti contends in her research that humans and the urban areas we create are having a strong, planetwide effect on evolution.

“Our premise is that Earth’s entry into the Anthropocene represents what might, from an astrobiological perspective, be a predictable planetary transition,” they write. “We explore this problem from the perspective of our own solar system and exoplanet studies.

“In our perspective, the beginning of the Anthropocene can be seen as the onset of the hybridization of the planet — a transitional stage from one class of planetary systems to another.”

That would be, in their scheme, Earth’s possible transition from Class IV — marked by a thick biosphere and life having some effect on the planet — to the final Class V, where a planet is profoundly affected by the activity of an advanced, energy-intensive species.

The classification scheme, the researchers write, is based on “the magnitude by which different planetary processes — abiotic, biotic and technologic — generate free energy, i.e. energy that can perform work within the system.”
  • Class I represents worlds with no atmosphere at all, such as the planet Mercury and the Earth’s moon.
  • Class II planets have a thin atmosphere containing greenhouse gases, but no current life, such as the current states of planets Mars and Venus.
  • Class III planets have perhaps a thin biosphere and some biotic activity, but much too little to “affect planetary drivers and alter the evolutionary state of the planet as a whole.” No current examples exist in the solar system, but early Earth may have represented such a world — and possibly early Mars, if life ever flickered there in the distant past.
  • Class IV planets have a thick biosphere sustained by photosynthetic activity and life has begun strongly affecting the planetary energy flow.
Alberti said, “The discovery of seven new exoplanets orbiting the relatively close star TRAPPIST-1 forces us to rethink life on Earth. It opens the possibility to broaden our understanding of coupled system dynamics and lay the foundations to explore a path to long-term sustainability by entering into a cooperative ecological-evolutionary dynamic with the coupled planetary systems.”

The researchers write, “Our thesis is that the development of long-term sustainable, versions of an energy-intensive civilization must be seen on a continuum of interactions between life and its host planet.”

The classifications lay the groundwork, they say, for future research on the “co-evolution” of planets along that continuum.

“Any world hosting a long-lived energy-intensive civilization must share at least some similarities in terms of the thermodynamic properties of the planetary system,” they write. “Understanding these properties, even in the broadest outlines, can help us understand which direction we must aim our efforts in developing a sustainable human civilization.”

In other words, they added, “If one does not know where one is going, it’s hard to get there.”

Co-author on the paper is Axel Kleidon of the Max Planck Institute for Biogeochemistry in Jena, Germany.