Excerpt from hubpages.com By Stephanie HicksWhat is Narcissism?Like many other psychological issues, there is a range of narcissism from mild to severe. Because of our inherent ego (as analyzed by Freud), a tendency to want to protect, celeb...
Tag: extreme (page 2 of 6)
This artist's illustration shows interstellar gas, the raw material of star formation, being blown away.Excerpt from cnet.com It takes a mighty wind to keep stars from forming. Researchers have found one in a galaxy far, far away -- and NASA mad...
Excerpt from clapway.com
If you can remember your primary school’s astronomy classes, the surface of a star is a very volatile place with tons of chemical reactions and extreme motions, and with immense gravitational pull. Generally a place you would not want to be. But researchers are now saying that if you were to orbit a star, it may be possible, with the right equipment, to hear what a star is saying! Or Singing?
Would you want to hear the sounds of stars?
The sound, unfortunately, is so high pitched that no mammal, not even a dolphin or bat, would be able to hear it, and couldn’t be heard anyway because space is a vacuum and there is no air medium for the sound to travel in.
With a frequency of nearly one trillion hertz, the sound was not only unexpected, but six million times higher than what any mammal can hear. But the researchers have developed a method to hear what they poetically refer to as “singing” or a star’s “song.”
Britain’s University of York’s researchers of hydrodynamics – the study of fluids in motion – fired a laser beam at the plasma in the laboratory and found that within a trillionth of a second, the plasma quickly moved from high-density to low-density areas.Plasma is a state of matter that makes up most things in the known universe and a few things on earth like lightning strikes and neon signs. It is basically a gas that has been charged with enough energy to loose the electrons from the atoms holding them together.
The spot where the low-density and high-density areas meet led to what the University researchers called a “traffic jam,” and resulted in an apparent sound wave, allowing us to know the sounds of stars.
Though this was achieved in the laboratory, scientists have yet to try to hear the sounds of a real star.
Dr. Pasley, a scientist from the Tata Institute of Fundamental Research in Mumbai, India, , said: “One of the few locations in nature where we believe this effect would occur is at the surface of stars. When they are accumulating new material stars could generate sound in a very similar manner to that which we observed in the laboratory–so the stars might be singing–but since sound cannot propagate through the vacuum of space, no-one can hear them.”
The technique used to observe the sound waves in the laboratory sort of works like a police speed camera, allowing scientists to accurately measure how the fluid would sound at the point of being struck by the laser at very minute timescales. The research was published in Physical Review Letters.
Perhaps in the future we might be able to listen in on the sounds of stars instead of just viewing it, and hear what they have to say!
Scientists in Australia have discovered what they say is the largest asteroid impact area ever found. Excerpt from bbc.comThe 400-kilometre (250-mile) wide area is buried deep in the earth's crust and consists of two separate impact scars.The...
Excerpt from smithsonianmag.com
In the hunt for alien life, our first glimpse of extraterrestrials may be in the rainbow of colors seen coming from the surface of an exoplanet.
That's the deceptively simple idea behind a study led by Siddharth Hegde at the Max Planck Institute for Astronomy in Germany. Seen from light-years away, plants on Earth give our planet a distinctive hue in the near-infrared, a phenomenon called red edge. That's because the chlorophyll in plants absorbs most visible light waves but starts to become transparent to wavelengths on the redder end of the spectrum. An extraterrestrial looking at Earth through a telescope could match this reflected color with the presence of oxygen in our atmosphere and conclude there is life here.
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| Eight of the 137 microorganism samples used to measure biosignatures for the catalog of reflection signatures of Earth life forms. In each panel, the top is a regular photograph of the sample and the bottom is a micrograph, a version of the top image zoomed-in 400 times. |
Plants, though, have only been around for 500 million years—a relative blip in our planet's 4.6-billion-year history. Microbes dominated the scene for some 2.5 billion years in the past, and some studies suggest they will rule the Earth again for much of its future. So Hegde and his team gathered 137 species of microorganisms that all have different pigments and that reflect light in specific ways. By building up a library of the microbes' reflectance spectra—the types of colors those microscopic critters reflect from a distance—scientists examining the light from habitable exoplanets can have a plethora of possible signals to search for, the team argues this week in the Proceedings of the National Academy of Sciences.
"No one had looked at the wide range of diverse life on Earth and asked how we could potentially spot such life on other planets, and include life from extreme environments on Earth that could be the 'norm' on other planets," Lisa Kaltenegger, a co-author on the study, says via email. "You can use it to model an Earth that is different and has different widespread biota and look how it would appear to our telescopes."
To make sure they got enough diversity, the researchers looked at temperate-dwelling microbes as well as creatures that live in extreme environments like deserts, mineral springs, hydrothermal vents or volcanically active areas.
While it might seem that alien life could take a huge variety of forms—for instance, something like the silicon-based Horta from Star Trek—it's possible to narrow things down if we restrict the search to life as we know it. First, any life-form that is carbon-based and uses water as a solvent isn't going to like the short wavelengths of light far in the ultraviolet, because this high-energy UV can damage organic molecules. At the other end of the spectrum, any molecule that alien plants (or their analogues) use to photosynthesize won't be picking up light that's too far into the infrared, because there's not enough energy at those longer wavelengths.
In addition, far-infrared light is hard to see through an Earth-like atmosphere because the gases block a lot of these waves, and whatever heat the planet emits will drown out any signal from surface life. That means the researchers restricted their library to the reflected colors we can see when looking at wavelengths in the visible part of the spectrum, the longest wavelength UV and short-wave infrared.
The library won't be much use if we can't see the planets' surfaces in the first place, and that's where the next generation of telescopes comes in, Kaltenegger says. The James Webb Space Telescope, scheduled for launch in 2018, should be able to see the spectra of relatively small exoplanet atmospheres and help scientists work out their chemical compositions, but it won't be able to see any reflected spectra from material at the surface. Luckily, there are other planned telescopes that should be able to do the job. The European Extremely Large Telescope, a 40-meter instrument in Chile, will be complete by 2022. And NASA's Wide Field Infrared Survey Telescope, which is funded and in its design stages, should be up and running by the mid-2020s.
Another issue is whether natural geologic or chemical processes could look like life and create a false signal. So far the pigments from life-forms look a lot different from those reflected by minerals, but the team hasn't examined all the possibilities either, says Kaltenegger. They hope to do more testing in the future as they build up the digital library, which is now online and free for anyone to explore at biosignatures.astro.cornell.edu.
Kepler’s Exoplanets: A map of the locations of exoplanets, of various masses, in the Kepler field of view. 1,235 candidates are plotted (NASA/Wendy Stenzel)
news.discovery.com
Just in case you haven’t heard, our galaxy appears to be teeming with small worlds, many of which are Earth-sized candidate exoplanets and dozens appear to be orbiting their parent stars in their “habitable zones.”
Before Wednesday’s Kepler announcement, we knew of just over 500 exoplanets orbiting stars in the Milky Way. Now the space telescope has added another 1,235 candidates to the tally — what a difference 24 hours makes.
Although this is very exciting, the key thing to remember is that we are talking about exoplanet candidates, which means Kepler has detected 1,235 exoplanet signals, but more work needs to be done (i.e. more observing time) to refine their orbits, masses and, critically, to find out whether they actually exist.
But, statistically speaking, a pattern is forming. Kepler has opened our eyes to the fact our galaxy is brimming with small worlds — some candidates approaching Mars-sized dimensions!
Earth-Brand™ Life
Before Kepler, plenty of Jupiter-sized worlds could be seen, but with its precision eye for spotting the tiniest of fluctuations of star brightness (as a small exoplanet passes between Kepler and the star), the space telescope has found that smaller exoplanets outnumber the larger gas giants.Needless to say, all this talk of “Earth-sized” worlds (and the much-hyped “Earth-like” misnomer) has added fuel to the extraterrestrial life question: If there’s a preponderance of small exoplanets — some of which orbit within the “sweet-spot” of the habitable zones of their parent stars — could life as we know it (or Earth-Brand™ Life as I like to call it) also be thriving there?
Before I answer that question, let’s turn back the clock to Sept. 29, 2010, when, in the wake of the discovery of the exoplanet Gliese 581 g, Steven Vogt, professor of astronomy and astrophysics at University of California Santa Cruz, told Discovery News: “Personally, given the ubiquity and propensity of life to flourish wherever it can, I would say that the chances for life on [Gliese 581 g] are 100 percent. I have almost no doubt about it.”
Impossible? Or 100 Percent?
As it turns out, Gliese 581 g may not actually exist — an excellent example of the progress of science scrutinizing a candidate exoplanet in complex data sets as my Discovery News colleague Nicole Gugliucci discusses in “Gliese 581g and the Nature of Science” — but why was Vogt so certain that there was life on Gliese 581 g? Was he “wrong” to air this opinion?Going to the opposite end of the spectrum, Howard Smith, an astrophysicist at Harvard University, made the headlines earlier this year when he announced, rather pessimistically, that aliens will unlikely exist on the extrasolar planets we are currently detecting.
“We have found that most other planets and solar systems are wildly different from our own. They are very hostile to life as we know it,” Smith told the UK’s Telegraph.
Smith made comparisons between our own solar system with the interesting HD 10180 system, located 127 light-years away. HD 10180 was famous for a short time as being the biggest star system beyond our own, containing five exoplanets (it has since been trumped by Kepler-11, a star system containing six exoplanets as showcased in Wednesday’s Kepler announcement).
One of HD 10180′s worlds is thought to be around 1.4 Earth-masses, making it the smallest detected exoplanet before yesterday. Alas, as Smith notes, that is where the similarities end; the “Earth-sized” world orbiting HD 10180 is too close to its star, meaning it is a roasted exoplanet where any atmosphere is blasted into space by the star’s powerful radiation and stellar winds.
Both Right and Wrong
So what can we learn about the disparity between Vogt and Smith’s opinions about the potential for life on exoplanets, regardless of how “Earth-like” they may seem?Critically, both points of view concern Earth-Brand™ Life (i.e. us and the life we know and understand). As we have no experience of any other kind of life (although the recent eruption of interest over arsenic-based life is hotly debated), it is only Earth-like life we can realistically discuss.
We could do a Stephen Hawking and say that all kinds of life is possible anywhere in the cosmos, but this is pure speculation. Science only has life on Earth to work with, so (practically speaking) it’s pointless to say a strange kind of alien lifeform could live on an exoplanet where the surface is molten rock and constantly bathed in extreme stellar radiation.
If we take Hawking’s word for it, Vogt was completely justified for being so certain about life existing on Gliese 581 g. What’s more, there’s no way we could prove he’s wrong!
But if you set the very tight limits on where we could find Earth-like life, we are suddenly left with very few exoplanet candidates that fit the bill. Also, just because an Earth-sized planet might be found in the habitable zone of its star, doesn’t mean it’s actually habitable. There are many more factors to consider. So, in this case, Smith’s pessimism is well placed.
Regardless, exoplanet science is in its infancy and the uncertainty with the “is there life?” question is a symptom of being on the “raggedy edge of science,” as Nicole would say. We simply do not know what it takes to make a world habitable for any kind of life (apart from Earth), but it is all too tempting to speculate as to whether a race of extraterrestrials, living on one of Kepler’s worlds, is pondering these same questions.
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| Artist's impression of Gliese 581d, a controversial exoplanet that may exist only 20 light-years from Earth. |
Excerpt from news.discovery.com
Despite having discovered nearly 2,000 alien worlds beyond our solar system, the profound search for exoplanets — a quest focused on finding a true Earth analog — is still in its infancy. It is therefore not surprising that some exoplanet discoveries aren’t discoveries at all; they are in fact just noise in astronomical data sets.
But when disproving the existence of extrasolar planets that have some characteristics similar to Earth, we need to take more care during the analyses of these data, argue astronomers from Queen Mary, University of London and the University of Hertfordshire.
In a paper published by the journal Science last week, the researchers focus on the first exoplanet discovered to orbit a nearby star within its habitable zone.
Revealed in 2009, Gliese 581d hit the headlines as a “super-Earth” that had the potential to support liquid water on its possibly rocky surface. With a mass of around 7 times that of Earth, Gliese 581d would be twice as big with a surface gravity around twice that of Earth. Though extreme, it’s not such a stretch of the imagination that such a world, if it is proven to possess an atmosphere and liquid ocean, that life could take hold.
And the hunt for life-giving alien worlds is, of course, the central motivation for exoplanetary studies.
But the exoplanet signal has been called into doubt.
Gliese 581d’s star, Gliese 581, is a small red dwarf around 20 light-years away. Red dwarfs are known to be tempestuous little stars, often generating violent flaring outbursts and peppered in dark features called starspots. To detect the exoplanet, astronomers measured the very slight frequency shift (Doppler shift) of light from the star — as the world orbits, it exerts a tiny gravitational “tug”, causing the star to wobble. When this periodic wobble is detected, through an astronomical technique known as the “radial velocity method,” a planet may be revealed.
Last year, however, in a publication headed by astronomers at The Pennsylvania State University, astronomers pointed to the star’s activity as an interfering factor that may have imitated the signal from an orbiting planet when in fact, it was just noisy data.
But this conclusion was premature, argues Guillem Anglada-Escudé, of Queen Mary, saying that “one needs to be more careful with these kind of claims.”
“The existence, or not, of GJ 581d is significant because it was the first Earth-like planet discovered in the ‘Goldilocks’-zone around another star and it is a benchmark case for the Doppler technique,” said Anglada-Escudé in a university press release. “There are always discussions among scientists about the ways we interpret data but I’m confident that GJ 581d has been in orbit around Gliese 581 all along. In any case, the strength of their statement was way too strong. If the way to treat the data had been right, then some planet search projects at several ground-based observatories would need to be significantly revised as they are all aiming to detect even smaller planets.”
The upshot is that this new paper challenges the statistical technique used in 2014 to account for the signal being stellar noise — focusing around the presence of starspots in Gliese 581′s photosphere.
Gliese 581d isn’t the only possible exoplanet that exists around that star — controversy has also been created by another, potentially habitable exoplanet called Gliese 581g. Also originally detected through the wobble of the star, this 3-4 Earth mass world was found to also be in orbit within the habitable zone. But its existence has been the focus of several studies supporting and discounting its presence. Gliese 581 is also home to 3 other confirmed exoplanets, Gliese 581e, b and c.
Currently, observational data suggests Gliese 581g was just noise, but as the continuing debate about Gliese 581d is proving, this is one controversy that will likely keep on rumbling in the scientific journals for some time.
Excerpt from independent.co.uk
By Jordan Gaines Lewis
In neuroscience, food is something we call a “natural reward.” In order for us to survive as a species, things like eating, having sex and nurturing others must be pleasurable to the brain so that these behaviours are reinforced and repeated.
Evolution has resulted in the mesolimbic pathway, a brain system that deciphers these natural rewards for us. When we do something pleasurable, a bundle of neurons called the ventral tegmental area uses the neurotransmitter dopamine to signal to a part of the brain called the nucleus accumbens. The connection between the nucleus accumbens and our prefrontal cortex dictates our motor movement, such as deciding whether or not to taking another bite of that delicious chocolate cake. The prefrontal cortex also activates hormones that tell our body: “Hey, this cake is really good. And I’m going to remember that for the future.”Not all foods are equally rewarding, of course. Most of us prefer sweets over sour and bitter foods because, evolutionarily, our mesolimbic pathway reinforces that sweet things provide a healthy source of carbohydrates for our bodies. When our ancestors went scavenging for berries, for example, sour meant “not yet ripe,” while bitter meant “alert – poison!”
Fruit is one thing, but modern diets have taken on a life of their own. A decade ago, it was estimated that the average American consumed 22 teaspoons of added sugar per day, amounting to an extra 350 calories; it may well have risen since then. A few months ago, one expert suggested that the average Briton consumes 238 teaspoons of sugar each week.
Today, with convenience more important than ever in our food selections, it’s almost impossible to come across processed and prepared foods that don’t have added sugars for flavour, preservation, or both.
These added sugars are sneaky – and unbeknown to many of us, we’ve become hooked. In ways that drugs of abuse – such as nicotine, cocaine and heroin – hijack the brain’s reward pathway and make users dependent, increasing neuro-chemical and behavioural evidence suggests that sugar is addictive in the same way, too.
Sugar addiction is real
Anyone who knows me also knows that I have a huge sweet tooth. I always have. My friend and fellow graduate student Andrew is equally afflicted, and living in Hershey, Pennsylvania – the “Chocolate Capital of the World” – doesn’t help either of us. But Andrew is braver than I am. Last year, he gave up sweets for Lent. “The first few days are a little rough,” Andrew told me. “It almost feels like you’re detoxing from drugs. I found myself eating a lot of carbs to compensate for the lack of sugar.”There are four major components of addiction: bingeing, withdrawal, craving, and cross-sensitisation (the notion that one addictive substance predisposes someone to becoming addicted to another). All of these components have been observed in animal models of addiction – for sugar, as well as drugs of abuse.
A typical experiment goes like this: rats are deprived of food for 12 hours each day, then given 12 hours of access to a sugary solution and regular chow. After a month of following this daily pattern, rats display behaviours similar to those on drugs of abuse. They’ll binge on the sugar solution in a short period of time, much more than their regular food. They also show signs of anxiety and depression during the food deprivation period. Many sugar-treated rats who are later exposed to drugs, such as cocaine and opiates, demonstrate dependent behaviours towards the drugs compared to rats who did not consume sugar beforehand.
Like drugs, sugar spikes dopamine release in the nucleus accumbens. Over the long term, regular sugar consumption actually changes the gene expression and availability of dopamine receptors in both the midbrain and frontal cortex. Specifically, sugar increases the concentration of a type of excitatory receptor called D1, but decreases another receptor type called D2, which is inhibitory. Regular sugar consumption also inhibits the action of the dopamine transporter, a protein which pumps dopamine out of the synapse and back into the neuron after firing.
In short, this means that repeated access to sugar over time leads to prolonged dopamine signalling, greater excitation of the brain’s reward pathways and a need for even more sugar to activate all of the midbrain dopamine receptors like before. The brain becomes tolerant to sugar – and more is needed to attain the same “sugar high.”
Sugar withdrawal is also real
Although these studies were conducted in rodents, it’s not far-fetched to say that the same primitive processes are occurring in the human brain, too. “The cravings never stopped, [but that was] probably psychological,” Andrew told me. “But it got easier after the first week or so.”In a 2002 study by Carlo Colantuoni and colleagues of Princeton University, rats who had undergone a typical sugar dependence protocol then underwent “sugar withdrawal.” This was facilitated by either food deprivation or treatment with naloxone, a drug used for treating opiate addiction which binds to receptors in the brain’s reward system. Both withdrawal methods led to physical problems, including teeth chattering, paw tremors, and head shaking. Naloxone treatment also appeared to make the rats more anxious, as they spent less time on an elevated apparatus that lacked walls on either side.
Similar withdrawal experiments by others also report behaviour similar to depression in tasks such as the forced swim test. Rats in sugar withdrawal are more likely to show passive behaviours (like floating) than active behaviours (like trying to escape) when placed in water, suggesting feelings of helplessness.
A new study published by Victor Mangabeira and colleagues in this month’s Physiology & Behavior reports that sugar withdrawal is also linked to impulsive behaviour. Initially, rats were trained to receive water by pushing a lever. After training, the animals returned to their home cages and had access to a sugar solution and water, or just water alone. After 30 days, when rats were again given the opportunity to press a lever for water, those who had become dependent on sugar pressed the lever significantly more times than control animals, suggesting impulsive behaviour.
These are extreme experiments, of course. We humans aren’t depriving ourselves of food for 12 hours and then allowing ourselves to binge on soda and doughnuts at the end of the day. But these rodent studies certainly give us insight into the neuro-chemical underpinnings of sugar dependence, withdrawal, and behaviour.
Through decades of diet programmes and best-selling books, we’ve toyed with the notion of “sugar addiction” for a long time. There are accounts of those in “sugar withdrawal” describing food cravings, which can trigger relapse and impulsive eating. There are also countless articles and books about the boundless energy and new-found happiness in those who have sworn off sugar for good. But despite the ubiquity of sugar in our diets, the notion of sugar addiction is still a rather taboo topic.
Are you still motivated to give up sugar? You might wonder how long it will take until you’re free of cravings and side-effects, but there’s no answer – everyone is different and no human studies have been done on this. But after 40 days, it’s clear that Andrew had overcome the worst, likely even reversing some of his altered dopamine signalling. “I remember eating my first sweet and thinking it was too sweet,” he said. “I had to rebuild my tolerance.”
And as regulars of a local bakery in Hershey – I can assure you, readers, that he has done just that.
Jordan Gaines Lewis is a Neuroscience Doctoral Candidate at Penn State College of Medicine
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| Illustration provided by the University of Heidelberg of the orbit of Kepler-432b (inner, red) in comparison to the orbit of Mercury around the Sun (outer, orange). The red dot in the middle indicates the position of the star around which the planet is orbiting. The size of the star is shown to scale, while the size of the planet has been magnified ten times for illustration purposes. (Graphic: Dr. Sabine Reffert) |
Excerpt from foxnews.com/science
A rare planet has been discovered, and it doesn’t seem like a stop anyone would want to make on an intergalactic cruise. Found by two research teams independently of each other, Kepler-432b is extreme in its mass, density, and weather. Roughly the same size of Jupiter, the planet is also doomed- in 200 million years it will be consumed by its sun. “Kepler-432b is definitively a rarity among exoplanets around giant stars: it is a close-in gas-giant planet orbiting a star whose radius is 'quickly' increasing,” Davide Gandolfi, from the Landessternwarte Koenigstuhl (part of the Centre for Astronomy of the University of Heidelberg), told FoxNews.com. “The orbit of the planet has a radius of about 45 million kilometers [28 million miles] (as a reference point, the Earth-Sun distance is about 150 million kilometers [93.2 Million miles]), while most of the planets known to orbit giant stars have wider orbits. The stellar radius is already 3 million kilometers [almost 2 million miles] (i.e., about 4 times the Sun radius) and in less than 200 million years it will be large enough for the star to swallow up its planet.”
Gandolfi, a member of one of the research groups who discovered the rare planet, explains that much like Jupiter, Kepler-432b is a gas-giant celestial body composed mostly of hydrogen and helium, and is most likely to have a dense core that accounts for 6 percent or less of the planet’s mass. “The planet has a mass six times that of Jupiter, but is about the same size!” he says. “This means that it is not one of the largest planets yet discovered: it is one of the most massive!” The planet’s orbit brings it extremely close to its host star on some occasions, and very far away at others, which creates extreme seasonal changes. In its year - which lasts 52 Earth days - winters can get a little chilly and summers a bit balmy, to say the least. According to Gandolfi, “The highly eccentric orbit brings Kepler-432b at ‘only’ 24 million kilometers [15 million miles] from its host star, before taking it to about three times as far away. This creates large temperature excursions over the course of the planet year, which is of only 52 Earth days. During the winter season, the temperature on Kepler-432b drops down to 500 degrees Celsius [932 degrees Fahrenheit], whereas in summer it can goes up to nearly 1000 degrees Celsius [1832 degrees Fahrenheit].”
Then again, if you are crazy enough to visit Kepler-432b, you’d better do it fast. As stated before, its host star is set to swallow the planet whole in 200 million years, making the celestial body a rare find. “The paucity of close-in planets around giant stars is likely to be due to the fact that these planets have been already swallowed up by their host stars,” Gandolfi says. “Kepler-432b has been discovered ‘just in time before dinner!” The host star, which is red and possesses 1.35 times the mass of our sun, has partly exhausted the nuclear fuel in its core, and is slowly expanding, eventually growing large enough to swallow Kepler-432b. According to Gandolfi, this is a natural progression for all stars. “Stars first generate nuclear energy in their core via the fusion of Hydrogen into Helium,” he explained. “At this stage, their radii basically do not change much. This is because the outward thermal pressure produced by the nuclear fusion in the core is balanced by the inward pressure of gravitational collapse from the overlying layers. In other words, the nuclear power is the star pillar! Our Sun is currently ‘burning’ hydrogen in its core (please note that I used quotes: ‘burning’ does not mean a chemical reaction- we are talking about nuclear fusion reaction). However, this equilibrium between the two pressures does not last forever. Helium is heavier than hydrogen and tends to sink. The stellar core of the Kepler-432b's host star is currently depleted of hydrogen and it is mainly made of inert helium. The star generates thermal energy in a shell around the core through the nuclear fusion of hydrogen into helium. As a result of this, the star expands and cools down. This is why we call it ‘red giant’- the reddish color comes from the fact that the external layers of the atmosphere of the star are cooling down because they expand.”
Both research teams (the other was from the Max Planck Institute for Astronomy in Heidelberg) used Calar Alto Observatory’s 7.2- foot telescope in Andalucia, Spain. The planet was also studied by Landessternwarte Koenigstuhl researchers using the 8.5-foot Nordic Optical Telescope on La Palma, which is located in Spain’s Canary Islands.
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| Mercury's extreme temperatures and lack of an atmosphere would make it very difficult, if not impossible, for people to live on the planet. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington |
Excerpt from space.com
By Joseph Castro, Space.com Contributor
Have you ever wondered what it might be like to homestead on Mars or walk on the moons of Saturn? So did we. This is the first in Space.com's 12-part series on what it might be like to live on or near planets in our solar system, and beyond. Check back each week for the next space destination.
With its extreme temperature fluctuations, Mercury is not likely a planet that humans would ever want to colonize. But if we had the technology to survive on the planet closest to the sun, what would it be like to live there?To date, only two spacecraft have visited Mercury. The first, Mariner 10, conducted a series of Mercury flybys in 1974, but the spacecraft only saw the lit half of the planet. NASA's MESSENGER spacecraft, on the other hand, conducted flybys and then entered Mercury's orbit — in March of 2013, images from the spacecraft allowed scientists to completely map the planet for the first time.
MESSENGER photos of Mercury show that the planet has water ice at its poles, which sit in permanent darkness. Mining this ice would be a good way to live off the land, but setting up bases at the poles might not be a good idea, said David Blewett, a participating scientist with the Messenger program.
"The polar regions would give you some respite from the strength of the sun on Mercury," Blewett told Space.com. "But, of course, it's really cold in those permanently shadowed areas where the ice is, and that presents its own challenge."
A better option, he said, would probably be to set up a home base not far from one of the ice caps, perhaps on a crater rim, and have a water mining operation at the pole.
Still, dealing with extreme temperatures on Mercury would likely be unavoidable: Daytime temperatures on the planet can reach 800 degrees Fahrenheit (430 degrees Celsius), while nighttime temperatures can drop down to minus 290 degrees Fahrenheit (minus 180 degrees Celsius).
Scientists once believed Mercury was tidally locked with the sun, meaning that one side of the planet always faces the sun because it takes the same amount of time to rotate around its axis as it does to revolve around the star. But we now know that Mercury's day lasts almost 59 Earth days and its year stretches for about 88 Earth days.
Interestingly, the sun has an odd path through the planet's sky over the course of Mercury's long day, because of the interaction between Mercury's spin rate and its highly elliptical orbit around the sun.
"It [the sun] rises in the east and moves across the sky, and then it pauses and moves backwards just a tad. It then resumes its motion towards the west and sunset," said Blewett, adding that the sun appears 2.5 times larger in Mercury's sky than it does in Earth's sky.
And during the day, Mercury's sky would appear black, not blue, because the planet has virtually no atmosphere to scatter the sun's light. "Here on Earth at sea level, the molecules of air are colliding billions of times per second," Blewett said. "But on Mercury, the atmosphere, or 'exosphere,' is so very rarefied that the atoms essentially never collide with other exosphere atoms." This lack of atmosphere also means that the stars wouldn't twinkle at night.
But Mercury isn't devoid of natural disasters. "The surface is exposed to impacts of all sizes," Blewett said. It also may suffer from earthquakes due to compressive forces that are shrinking the planet (unlike Earth, Mercury doesn't have tectonic activity).
Mercury is about two-fifths the size of Earth, with a similar gravity to Mars, or about 38 percent of Earth's gravity. This means that you could jump three times as high on Mercury, and heavy objects would be easier to pick up, Blewett said. However, everything would still have the same mass and inertia, so you could be knocked over if someone threw a heavy object at you, he added.
Finally, you can forget about a smooth Skype call home: It takes at least 5 minutes for signals from Mercury to reach Earth, and vice versa.
Excerpt from space.com
The moon has long been viewed as a crucial component in creating an environment suitable for the evolution of complex life on Earth, but a number of scientific results in recent years have shown that perhaps our planet doesn't need the moon as much as we have thought.
In 1993, French astronomer Jacques Laskar ran a series of calculations indicating that the gravity of the moon is vital to stabilizing the tilt of our planet. Earth's obliquity, as this tilt is technically known as, has huge repercussions for climate. Laskar argued that should Earth's obliquity wander over hundreds of thousands of years, it would cause environmental chaos by creating a climate too variable for complex life to develop in relative peace.
So his argument goes, we should feel remarkably lucky to have such a large moon on our doorstep, as no other terrestrial planet in our solar system has such a moon. Mars' two satellites, Phobos and Deimos, are tiny, captured asteroids that have little known effect on the Red Planet. Consequently, Mars' tilt wobbles chaotically over timescales of millions of years, with evidence for swings in its rotational axis at least as large as 45 degrees.
The stroke of good fortune that led to Earth possessing an unlikely moon, specifically the collision 4.5 billion years ago between Earth and a Mars-sized proto-planet that produced the debris from which our Moon formed, has become one of the central tenets of the 'Rare Earth' hypothesis. Famously promoted by Peter Ward and Don Brownlee, it argues that planets where everything is just right for complex life are exceedingly rare.
New findings, however, are tearing up the old rule book. In 2011, a trio of scientists — Jack Lissauer of NASA Ames Research Center, Jason Barnes of the University of Idaho and John Chambers of the Carnegie Institution for Science — published results from new simulations describing what Earth's obliquity would be like without the moon. What they found was surprising.
"We were looking into how obliquity might vary for all sorts of planetary systems," says Lissauer. "To test our code we began with integrations following the obliquity of Mars and found similar results to other people. But when we did the obliquity of Earth we found the variations were much smaller than expected — nowhere near as extreme as previous calculations suggested they would be."
Lissauer's team found that without the moon, Earth's rotational axis would only wobble by 10 degrees more than its present day angle of 23.5 degrees. The reason for such vastly different results to those attained by Jacques Laskar is pure computing power. Today's computers are much faster and capable of more accurate modeling with far more data than computers of the 1990s.
Lissauer and his colleagues also found that if Earth were spinning fast, with one day lasting less than 10 hours, or rotating retrograde (i.e. backwards so that the sun rose in the West and set in the East), then Earth stabilized itself thanks to the gravitational resonances with other planets, most notably giant Jupiter. There would be no need for a large moon.
Earth's rotation has not always been as leisurely as the current 24 hour spin-rate. Following the impact that formed the moon, Earth was spinning once every four or five hours, but it has since gradually slowed by the moon's presence. As for the length of Earth's day prior to the moon-forming impact, nobody really knows, but some models of the impact developed by Robin Canup of the Southwest Research Institute, in Boulder, Colorado, suggest that Earth could have been rotating fast, or even retrograde, prior to the collision.
Planets with inclined orbits could find that their increased obliquity is beneficial to their long-term climate – as long as they do not have a large moon.
"Collisions in the epoch during which Earth was formed determined its initial rotation," says Lissauer. "For rocky planets, some of the models say most of them will be prograde, but others say comparable numbers of planets will be prograde and retrograde. Certainly, retrograde worlds are not expected to be rare."
The upshot of Lissauer's findings is that the presence of a moon is not the be all and end all as once thought, and a terrestrial planet can exist without a large moon and still retain its habitability. Indeed, it is possible to imagine some circumstances where having a large moon would actually be pretty bad for life.
Rory Barnes, of the University of Washington, has also tackled the problem of obliquity, but from a different perspective. Planets on the edge of habitable zones exist in a precarious position, far enough away from their star that, without a thick, insulating atmosphere, they freeze over, just like Mars. Barnes and his colleagues including John Armstrong of Weber State University, realized that torques from other nearby worlds could cause a planet's inclination to the ecliptic plane to vary. This in turn would result in a change of obliquity; the greater the inclination, the greater the obliquity to the Sun. Barnes and Armstrong saw that this could be a good thing for planets on the edges of habitable zones, allowing heat to be distributed evenly over geological timescales and preventing "Snowball Earth" scenarios. They called these worlds "tilt-a-worlds," but the presence of a large moon would counteract this beneficial obliquity change.
"I think one of the most important points from our tilt-a-world paper is that at the outer edge of the habitable zone, having a large moon is bad, there's no other way to look at it," says Barnes. "If you have a large moon that stabilizes the obliquity then you have a tendency to completely freeze over."
Barnes is impressed with the work of Lissauer's team.
"I think it is a well done study," he says. "It suggests that Earth does not need the moon to have a relatively stable climate. I don't think there would be any dire consequences to not having a moon."
The effects of changing obliquity on Mars’ climate. Mars’ current 25-degree tilt is seen at top left. At top right is a Mars that has a high obliquity, leading to ice gather at its equator while the poles point sunwards. At bottom is Mars with low obliquity, which sees its polar caps grow in size.
Of course, the moon does have a hand in other factors important to life besides planetary obliquity. Tidal pools may have been the point of origin of life on Earth. Although the moon produces the largest tides, the sun also influences tides, so the lack of a large moon is not necessarily a stumbling block. Some animals have also evolved a life cycle based on the cycle of the moon, but that's more happenstance than an essential component for life.
"Those are just minor things," says Lissauer.
Without the absolute need for a moon, astrobiologists seeking life and habitable worlds elsewhere face new opportunities. Maybe Earth, with its giant moon, is actually the oddball amongst habitable planets. Rory Barnes certainly doesn't think we need it.
"It will be a step forward to see the myth that a habitable planet needs a large moon dispelled," he says, to which Lissauer agrees.
Earth without its moon might therefore remain habitable, but we should still cherish its friendly presence. After all, would Beethoven have written the Moonlight Sonata without it?
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At the center of spiral galaxy M81 is a supermassive black hole about 70 million times more massive than our sun. |
Excerpt from insidescience.org
A physicist presents a solution to present-day cosmic mysteries.
By:
Nikodem Poplawski, Inside Science Minds Guest Columnist
(ISM) -- Our universe may exist inside a black hole. This may sound strange, but it could actually be the best explanation of how the universe began, and what we observe today. It's a theory that has been explored over the past few decades by a small group of physicists including myself.
Successful as it is, there are notable unsolved questions with the standard big bang theory, which suggests that the universe began as a seemingly impossible "singularity," an infinitely small point containing an infinitely high concentration of matter, expanding in size to what we observe today. The theory of inflation, a super-fast expansion of space proposed in recent decades, fills in many important details, such as why slight lumps in the concentration of matter in the early universe coalesced into large celestial bodies such as galaxies and clusters of galaxies.
But these theories leave major questions unresolved. For example: What started the big bang? What caused inflation to end? What is the source of the mysterious dark energy that is apparently causing the universe to speed up its expansion?
The idea that our universe is entirely contained within a black hole provides answers to these problems and many more. It eliminates the notion of physically impossible singularities in our universe. And it draws upon two central theories in physics.
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| In this picture, spins in particles interact with spacetime and endow it with a property called "torsion." To understand torsion, imagine spacetime not as a two-dimensional canvas, but as a flexible, one-dimensional rod. Bending the rod corresponds to curving spacetime, and twisting the rod corresponds to spacetime torsion. If a rod is thin, you can bend it, but it's hard to see if it's twisted or not. |
The first is general relativity, the modern theory of gravity. It describes the universe at the largest scales. Any event in the universe occurs as a point in space and time, or spacetime. A massive object such as the Sun distorts or "curves" spacetime, like a bowling ball sitting on a canvas. The Sun's gravitational dent alters the motion of Earth and the other planets orbiting it. The sun's pull of the planets appears to us as the force of gravity.
The second is quantum mechanics, which describes the universe at the smallest scales, such as the level of the atom. However, quantum mechanics and general relativity are currently separate theories; physicists have been striving to combine the two successfully into a single theory of "quantum gravity" to adequately describe important phenomena, including the behavior of subatomic particles in black holes.
A 1960s adaptation of general relativity, called the Einstein-Cartan-Sciama-Kibble theory of gravity, takes into account effects from quantum mechanics. It not only provides a step towards quantum gravity but also leads to an alternative picture of the universe. This variation of general relativity incorporates an important quantum property known as spin. Particles such as atoms and electrons possess spin, or the internal angular momentum that is analogous to a skater spinning on ice.
Spacetime torsion would only be significant, let alone noticeable, in the early universe or in black holes. In these extreme environments, spacetime torsion would manifest itself as a repulsive force that counters the attractive gravitational force coming from spacetime curvature. As in the standard version of general relativity, very massive stars end up collapsing into black holes: regions of space from which nothing, not even light, can escape.
Here is how torsion would play out in the beginning moments of our universe. Initially, the gravitational attraction from curved space would overcome torsion's repulsive forces, serving to collapse matter into smaller regions of space. But eventually torsion would become very strong and prevent matter from compressing into a point of infinite density; matter would reach a state of extremely large but finite density. As energy can be converted into mass, the immensely high gravitational energy in this extremely dense state would cause an intense production of particles, greatly increasing the mass inside the black hole.
The increasing numbers of particles with spin would result in higher levels of spacetime torsion. The repulsive torsion would stop the collapse and would create a "big bounce" like a compressed beach ball that snaps outward. The rapid recoil after such a big bounce could be what has led to our expanding universe. The result of this recoil matches observations of the universe's shape, geometry, and distribution of mass.
In turn, the torsion mechanism suggests an astonishing scenario: every black hole would produce a new, baby universe inside. If that is true, then the first matter in our universe came from somewhere else. So our own universe could be the interior of a black hole existing in another universe. Just as we cannot see what is going on inside black holes in the cosmos, any observers in the parent universe could not see what is going on in ours.
The motion of matter through the black hole's boundary, called an "event horizon," would only happen in one direction, providing a direction of time that we perceive as moving forward. The arrow of time in our universe would therefore be inherited, through torsion, from the parent universe.
Torsion could also explain the observed imbalance between matter and antimatter in the universe. Because of torsion, matter would decay into familiar electrons and quarks, and antimatter would decay into "dark matter," a mysterious invisible form of matter that appears to account for a majority of matter in the universe.
Finally, torsion could be the source of "dark energy," a mysterious form of energy that permeates all of space and increases the rate of expansion of the universe. Geometry with torsion naturally produces a "cosmological constant," a sort of added-on outward force which is the simplest way to explain dark energy. Thus, the observed accelerating expansion of the universe may end up being the strongest evidence for torsion.
Torsion therefore provides a theoretical foundation for a scenario in which the interior of every black hole becomes a new universe. It also appears as a remedy to several major problems of current theory of gravity and cosmology. Physicists still need to combine the Einstein-Cartan-Sciama-Kibble theory fully with quantum mechanics into a quantum theory of gravity. While resolving some major questions, it raises new ones of its own. For example, what do we know about the parent universe and the black hole inside which our own universe resides? How many layers of parent universes would we have? How can we test that our universe lives in a black hole?
The last question can potentially be investigated: since all stars and thus black holes rotate, our universe would have inherited the parent black hole’s axis of rotation as a "preferred direction." There is some recently reported evidence from surveys of over 15,000 galaxies that in one hemisphere of the universe more spiral galaxies are "left-handed", or rotating clockwise, while in the other hemisphere more are "right-handed", or rotating counterclockwise. In any case, I believe that including torsion in geometry of spacetime is a right step towards a successful theory of cosmology.
Excerpt from spacedaily.com For nearly half a century, theoretical physicists have made a series of discoveries that certain constants in fundamental physics seem extraordinarily fine-tuned to allow for the emergence of a life-enabling universe.Thi...
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