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RE: The Universe? - Pckts - 09-18-2014
AU (astronomical units)One AU is the distance that the average distance that the Earth orbits the Sun at. The AUis most commonly used for the distances of objects with in our solar system. Pluto, the last planet in the solar system is found at an average distance of 39.47 au from the Sun. Sedna the new body nearly as large as a planet found beyond Pluto is never nearer to the Sun than 76AU and then goes to 880AU from the Sun in its giant elliptical orbit.Light Years
One of the most common rulers is the light year. The light year is is the distance that light travel in one year (365 1/4 days). It is most commonly used for the distances to stars and other galaxies.
The nearest star is 4.2 light years away from our sun. We are 8.3 light minutes away form the Sun. the distance to the outer most planet Pluto is about 13 light hours.
Some other interesting distances in light years
bjectDistance in light yearsNearest Star (Proxima Centuri)4.2Sirius the dog star (the brightest star in the sky)8.6centre of the galaxyapproximately 30 000Andromeda (one of our nearest neighbouring galaxies)approximately 2 million
The stars of Orion. (Betelgeuse and Rigel)1400 light years
Parsec (pc)
Astronomers started measuring distances from the amount that a star moves as the Earth goes from one side of the Sun to the other. Try moving your head and you will see that the postion of everything around you changes.
One parsec is derived from the smallest angle measurement of 1/3,600th of a degree or an arc second that is the angle that a star at this distance would appear to move in 6 months as the Earth journeys around the Sun. A parsec is 3.2616 light years or 30,857,000,000,000 km..
Two parsecs is 6.5532 light years or twice the distance, it is not a measure of change in angles of the stars. Due to the massive distance in the universe astronomers often use multiples of parsec commonly found are kiloparsec (kpc) a 1000 parsecs or a megaparsec (Mpc) 1,000,000 parsecs.
Below is a conversion table for some useful astronomical distance units kilometres (km)Astronomical units (AU)Light Years (l.y.)Parsec (pc)kilometres (km)1149.6 million9,460,000,000,00030,857,000,000,000Astronomical units (AU)0.0000000067163,240206,263Light Years (l.y.)0.000000000000110.00001613.2616Parsec (pc)0.0000000000000330.00000480.30661
http://www.telescope.org/nuffield_21_sci/astrounits.htm
RE: The Universe? - Pckts - 09-18-2014
The Probability of a Collision with EarthThe Probability of Collisions with EarthMost bodies in the solar system with a visible solid surface exhibit craters. On Earth we see very few because geological processes such as weathering and erosion soon destroy the obvious evidence. On bodies with no atmosphere, such as Mercury or the Moon, craters are everywhere. Without going into detail, there is strong evidence of a period of intense cratering in the solar system that ended about 3.9 billion years ago. Since that time cratering appears to have continued at a much slower and fairly uniform rate. The cause of the craters is impacts by comets and asteroids. Most asteroids follow simple circular orbits between the planets Mars and Jupiter, but all of these asteroids are perturbed, occasionally by each other and more regularly and dramatically by Jupiter. As a result some find themselves in orbits that cross that of Mars or even Earth. Comets on the other hand follow highly elongated orbits that often come close to Earth or other major bodies to begin with. These orbits are greatly affected if they come anywhere near Jupiter. Over the eons every moon and planet finds itself in the wrong place in its orbit at the wrong time and suffers the insult of a major impact.The Earth's atmosphere protects us from the multitude of small debris, the size of grains of sand or pebbles, thousands of which pelt our planet every day. The meteors in our night sky are visible evidence of this small debris burning up high in the atmosphere. In fact, up to a diameter of about 10-meters (33 feet), most stony meteoroids are destroyed in the atmosphere in thermal explosions. Obviously some fragments do reach the ground, because we have stony meteorites in our museums. Such falls are known to cause property damage from time to time. On October 9, 1992, a fire ball was seen streaking across the sky all the way from Kentucky to New York. A 27-pound stony meteorite (chondrite) from the fireball fell in Peekskill, New York, punching a hole in the rear end of an automobile parked in a driveway and coming to rest in a shallow depression beneath it. Falls into a Connecticut dining room and an Alabama bedroom are well documented incursions in this century. A 10-meter body typically has the kinetic energy of about five nuclear warheads of the size dropped on Hiroshima, however, and the shock wave it creates can do considerable damage even if nothing but comparatively small fragments survive to reach the ground. Many fragments of a 10-meter iron meteoroid will reach the ground. The only well-studied example of such a fall in recent times took place in the Sikhote-Alin Mountains of eastern Siberia on February 12, 1947. About 150 US tons of fragments reached the ground, the largest intact fragment weighing 3,839 pounds. The fragments covered an area of about 1 x 2 kilometers (0.6 x 1.2 miles), within which there were 102 craters greater than 1 meter in diameter, the largest of them 26.5 meters (87 feet), and about 100 more smaller craters. If this small iron meteoroid had landed in a city, it obviously would have created quite a stir. The effect of the larger pieces would be comparable to having a car suddenly drop in at supersonic speeds! Such an event occurs about once per decade somewhere on Earth, but most of them are never recorded, occurring at sea or in some remote region such as Antarctica. It is a fact that there is no record in modern times of any person being killed by a meteorite. It is the falls larger than 10 meters that start to become really worrisome. The 1908 Tunguska event was a stony meteorite in the 100-meter class. The famous meteor crater in northern Arizona, some 1219 meters (4,000 feet) in diameter and 183 meters (600 feet) deep, was created 50,000 years ago by a nickel-iron meteorite perhaps 60 meters in diameter. It probably survived nearly intact until impact, at which time it was pulverized and largely vaporized as its 6-7 x 1016 joules* of kinetic energy were rapidly dissipated in an explosion equivalent to some 15 million tons of TNT! Falls of this class occur once or twice every 1000 years.There are now over 100 ring-like structures on Earth recognized as definite impact craters. Most of them are not obviously craters, their identity masked by heavy erosion over the centuries, but the minerals and shocked rocks present make it clear that impact was their cause. The Ries Crater in Bavaria is a lush green basin some 25 kilometers (15 miles) in diameter with the city of Nordlingen in the middle. Fifteen million years ago a 1500-meter (5000 feet) asteroid or comet hit there, excavating more than a trillion tons of material and scattering it all over Europe. This sort of thing happens about once every million years or so. Another step upward in size take us to Chicxulub, an event that occurs once in 50-100 million years. Chicxulub is the largest crater known which seems definitely to have an impact origin, but there are a few ring-like structures that are 2-3 times larger yet about which geologists are uncertain. There are now more than 150 asteroids known that come nearer to the Sun than the outermost point of Earth's orbit. These range in diameter from a few meters up to about 8 kilometers. A working group chaired by Dr. David Morrison, NASA Ames Research Center, estimates that there are some 2,100 such asteroids larger than 1 kilometer and perhaps 320,000 larger than 100 meters, the size that caused the Tunguska event and the Arizona Meteor Crater. An impact by one of these larger meteors in the wrong place would be a catastrophe, but it would not threaten civilization. However, the working group concluded that an impact by an asteroid larger than 1-2 kilometers could degrade the global climate, leading to widespread crop failure and loss of life. Such global environmental catastrophes, which place the entire population of the Earth at risk, are estimated to take place several times per million years on average. A still larger impact by an object larger than about 5 kilometers is damaging enough to cause mass extinctions. In addition there are many comets in the 1-10 kilometer class, 15 of them in short-period orbits that pass inside the Earth's orbit, and an unknown number of long-period comets. Virtually any short-period comet among the 100 or so not currently coming near the Earth could become dangerous after a close passage by Jupiter.This all sounds pretty scary. However, as noted earlier, no human in the past 1000 years is known to have been killed by a meteorite or by the effects of one impacting. (There are ancient Chinese records of such deaths.) An individual's chance of being killed by a meteorite is small, but the risk increases with the size of the impacting comet or asteroid, with the greatest risk associated with global catastrophes resulting from impacts of objects larger than 1 kilometer. NASA knows of no asteroid or comet currently on a collision course with Earth, so the probability of a major collision is quite small. In fact, as best as we can tell, no large object is likely to strike the Earth any time in the next several hundred years. To be able to better calculate the statistics, astronomers need to detect as many of the near-Earth objects as possible. It's likely that we could identify a threatening near-Earth object large enough to potentially cause catastrophic changes in the Earth's environment, and most astronomers believe that a systematic approach to studying asteroids and comets that pass close to the Earth makes good sense. It's too late for the dinosaurs, but today astonomers are conducting ever-increasing searches to identify all of the larger objects which pose an impact danger to Earth. * joule: a unit of measurement, the amount of energy corresponding to one watt acting for one second.
http://www2.jpl.nasa.gov/sl9/back2.html
RE: The Universe? - GuateGojira - 09-18-2014
(09-17-2014, 11:20 PM)'Pckts' Wrote: Gravity was a theory before it was a law.In fact, the concepts of "Theory" and "Law" were dubious in the time of Newton, however, he describe his statements as "laws", so in this case, it seems that Gravity was in fact, a "law" since the beginning. I could be wrong, but this is what I remember.
All discoveries are theories until they are Proven. The world being round was a theory, the gravitational pull of the sun was a theory, rotating around the sun was a theory, etc.
Not sure what you're trying to say here.
These ideas I posted are based off of scientific evidence, they are by no means "proven" but they certainly have enough evidence behind them to be more likely than the original ideas we had before.
About the modern Physics, most of they postulates are only in paper and based in equation and numbers, as it is not possible to prove them yet. Maybe, in the future, with better instruments, we will able to prove (or disprove) them and establish new laws.
In fact, what I try to say is that many modern scientists are reluctant to acept or even investigate new points of view. Check for example, all our investigations and results on animals, they will be rejected by many scientists, just because they don't came from "graduated" persons, because they are not written in a journal or because is not in a "book". However, this happen many times in the Universities, and if you don't follow the line, they exclude you.
RE: The Universe? - Pckts - 09-18-2014
Nothing is a law until proven. All ideas are first hypothesis and a Law still doesn't state how or why it happens.
"While the law lets us calculate quite a bit about what happens, notice that it does not tell us anything about why it happens. That is what theories are for. In the language of science, the word "theory" is used to describe an explanation of why and how things happen. For gravity, we use Einstein's Theory of General Relativity to explain why things fall. "
http://thehappyscientist.com/science-experiment/gravity-theory-or-law
"A theory starts as one or more hypotheses, untested ideas about why something happens. For example, I might propose a hypothesis that the object that you released fell because it was pulled by the Earth's magnetic field. Once we started testing, it would not take long to find out that my hypothesis was not supported by the evidence. Non-magnetic objects fall at the same rate as magnetic objects. Because it was not supported by the evidence, my hypothesis does not gain the status of being a theory. To become a scientific theory, an idea must be thoroughly tested, and must be an accurate and predictive description of the natural world.While laws rarely change, theories change frequently as new evidence is discovered. Instead of being discarded due to new evidence, theories are often revised to include the new evidence in their explanation. The Theory of General Relativity has adapted as new technologies and new evidence have expanded our view of the universe.So when we are scientifically discussing gravity, we can talk about the law that describes the attraction between two objects, and we can also talk about the theory that describes why the objects attract each other."
As you can see, one has nothing to do with the other. The theories come from evidence that we obtain, while a theory can change as new evidence is found, a law is only come from the ideas we research and theorize.
People used wonder why something feel to the ground, they would theorize ideas as to why, until a law that proved it come to pass. One is not the other
RE: The Universe? - GuateGojira - 09-19-2014
You have not understood what I said. I am NOT discussing semantic or terminologies here, I clearly showed the idea but you simply copy-paste theory from the Internet. Every single people here already know what is an hypothesis, or a theory, or a law.
Besides, take another read, check that I clearly said "In the time of Newton". Where your articles written in his time??? Of course not, modern science terminology is different than the one used in the year 1500, 1700 or even 1900.
Check for example the concept of "subspecies", in 1900 it was based only in the superficial morphological differences and was the base of Taxonomy. Now, the modern concept use DNA and this is the base of the Phylogeny. So, in less than 60 years, the full concept of taxonomical classifications has change. The concept of "subspecies" of 1940 was not the same than the one in the 2000.
Finally, let's not skip the important thing, the reluctance of modern science to study (or accept) new ideas. THIS is my point.
RE: The Universe? - brotherbear - 09-19-2014
When I was a kid growing up in the 1950s, dinosaurs were cold blooded reptiles living in swamps and moving about sluggishly while dragging their tails in the mud. Today, a dinosaur is a completely different animal. It took me some time to get used to the new idea.
RE: The Universe? - Pckts - 09-19-2014
Ok Gaute,
Pretty sure everything I posted explains the difference between Law and theory. The links and excerpts specifically tie into the discussion at hand and explain how you cannot have a Law until theories are first established.
Back to the topic....
RE: The Universe? - Pckts - 09-19-2014
Indeed Caos, with new technology and research, new ideas come to life.
Remember when people thought the sun revovled around the earth and the earth was flat?
People have come a long way in a relatively short time.
RE: The Universe? - Pckts - 09-22-2014
Top 10 usolved Mysteries of our Universe
Despite what cable news may tell you, scientists don’t really squabble over if evolution is real (it is) or if the climate is changing faster than can be explained by naturally-occurring phenomena (it is) or if vaccines are regarded as safe and recommended for most children (they are). Sure, there may be fine points within those categories that are debatable, but not to the extent that is commonly described by talking heads on TV. However, that’s not to say that scientists perfectly understand everything about the ways of the Universe.Physicist Brian Cox once said: “I'm comfortable with the unknown—that’s the point of science. There are places out there, billions of places out there, that we know nothing about. And the fact that we know nothing about them excites me, and I want to go out and find out about them. And that's what science is. So I think if you’re not comfortable with the unknown, then it’s difficult to be a scientist… I don’t need an answer. I don’t need answers to everything. I want to have answers to find.” So what are some of the top mysteries keeping scientists busy?
Here’s our top ten:
Why is there more matter than antimatter?According to our current understanding of particle physics, matter and antimatter are equal but opposite. When they meet, they should destroy one another and leave nothing left over, and most of those annihilation's should have occurred early in the Universe. However, there was enough matter left over to make the billions and billions of galaxies, stars, planets, and everything else. Various explanations surround mesons, which are short-lived subatomic particles made of one quark and one antiquark. B-mesons decay more slowly than anti-B-mesons, which could have resulted in enough B-mesons surviving the interaction to create all of the matter in the Universe. Additionally, B-, D-, and K-mesons can oscillate and become antiparticles and then back again. Studies have suggested that mesons are more likely to assume the normal state, which may also be why regular particles outnumber antiparticles.
Where is all the lithium?Early in the Universe when temperatures were incredibly high, isotopes of hydrogen, helium, and lithium were synthesized in abundance. Hydrogen and helium are still incredibly abundant and make up nearly all of the mass in the Universe, though there is only about a third of the lithium-7 that we should see. There are a wide variety of explanations for why this might have happened, including some hypotheses involving hypothetical bosons known as axions, and others believe it is trapped in the core of stars, which our current telescopes and instruments can’t detect. However, there are currently no clear front running theories to explain this absence of lithium in the Universe.
Why do we sleep?While we do know that the human body is regulated by a circadian clock that keeps humans on a sleep/wake cycle, we don’t really know why. Sleep is the time when our bodies repair tissues and perform other maintenance activities, and we spend nearly a third of our lives snoozing. Some other organisms don’t need to sleep at all, so why do we? There are a few different ideas out there, but none seem to solidly answer the question. Some theorize that animals who are able to sleep have evolved the ability to hide from predators, while others who need to remain more alert are able to rest and regenerate in other ways without fully going to sleep. While scientists don’t quite know why we do it, they are starting to learn more about why it is important, and how sleep impacts important things like brain plasticity.
How does gravity work?We all know that gravity from the moon causes tides, Earth’s gravity holds us to the surface, and the sun’s gravity keeps our planet in orbit, but how much do we really understand it? This powerful force is generated from matter, and more massive objects therefore have a greater ability to attract other objects. While scientists do understand a great deal about how gravity acts, they aren’t really sure why it exists. Why are atoms mostly empty space? Why is the force that holds atoms together different from gravity? Is gravity actually a particle? These are answers that we really just can’t answer with our current understand of physics.
Where is everyone?The observable Universe is 92 billion light-years in diameter, filled with billions of galaxies with stars and planets, yet the only evidence of any life anywhere is right here on Earth. Statistically, the odds of us actually being the only living beings in the Universe are impossibly low, so why the hell haven’t we connected with anyone else yet? This is known as the Fermi Paradox, and there have been dozens of suggestions to explain why we haven’t encountered extraterrestrial life; some more plausible than others. We could probably talk about all of the different possibilities for days about whether or not we’re just missing signals, if they’ve actually been here and we didn’t know it, they can’t/don’t want to talk to us, or—the extremely unlikely scenario—if Earth is the only planet with life ever.
What is dark matter made of?About 80% of all mass in the Universe is made of dark matter. Dark matter is pretty peculiar stuff, as it doesn’t emit any light. Though it was first theorized about 60 years ago, there isn’t any direct evidence of its existence. Many scientists believe dark matter is comprised of weakly interacting massive particles (WIMPs), which could be up to 100 times more massive than a proton, but doesn’t readily interact with the baryonic matter our instruments were designed to detect. Other candidates for dark matter’s composition include axions, neutralinos, and photinos.
How did life begin?Where did life on Earth come from? How did it happen? Those who believe in the Primordial Soup model believe that a nutrient-rich early Earth eventually formed increasingly-complex molecules that gave rise to life. This could have taken place in the deep ocean vents, in clay, or under ice. Different models also give variable levels of importance to the presence of lightning or volcanic activity for the spawn of life. While DNA is the predominant basis for life on Earth now, it has been suggested that RNA could have dominated the first lifeforms. Additionally, other scientists question whether other nucleic acids aside from RNA or DNA may have once existed. Did life spawn just once, or is it possible that is was created, wiped out, and then restarted? Some believe in panspermia, in which microbial life was brought to Earth via meteorites or comets. Even if that is true, it doesn’t answer the question of how that life originated.
How do plate tectonics work?It might sound surprising, but the theory of continental plates moving around, rearranging continents and causing earthquakes, volcanic eruptions, and even forming mountains, has only received widespread support relatively recently. Though it was first postulated back around 1500 that the continents may have once fit together (it’s not really a stretch for anyone who has looked at a map), the idea didn’t gain a lot of traction until the 1960s when the hypothesis of sea-floor spreading, where rocks are pulled into the mantle of the Earth, recycled, and brought back to the surface as magma, was backed up by physical evidence. However, scientists aren’t entirely sure on what drives this movement or exactly how plate boundaries were created. There are many theories, but none of them completely address all aspects of this activity.
How do animals migrate?Many animals and insects migrate throughout the year in order to escape changing seasonal temperatures and the waning resources that come with it or to find mates. Some of these migrations can reach thousands of kilometers in one direction, so how do they find their way there and back again year after year? Different animals use different navigational tools, including some who are able to tap into the Earth’s magnetic field and use themselves like a compass. However, scientists still don’t know how this trait evolved or how untrained animals know exactly where to go season after season.
What is dark energy?Of all of the great mysteries of science, dark energy might be the most enigmatic of all. While dark matter makes up an estimated 80% of all mass, dark energy is a hypothetical form of energy believed to make up around 70% of all content in the Universe. Dark energy has been implicated as the cause for the expansion of the Universe, though there is still a considerable amount of mystery regarding its supposed properties. First and foremost, what is it even made of? Is dark energy constant, or are there fluctuations throughout the expanse of space? Why does dark energy’s density appear to match the density of regular matter? Can dark energy be reconciled with Einstein’s theory of gravity, or does the theory need to be reevaluated?
http://www.iflscience.com/physics/top-10-unsolved-mysteries-science
RE: The Universe? - Pckts - 10-05-2014
4 year time lapse of an Exploding star
http://www.break.com/video/4-year-time-lapse-of-an-exploding-star-2773771
RE: The Universe? - Pckts - 10-08-2014
Older article on Dark EnergyTwice a day, seven days a week, from February to November for the past four years, two researchers have layered themselves with thermal underwear and outerwear, with fleece, flannel, double gloves, double socks, padded overalls and puffy red parkas, mummifying themselves until they look like twin Michelin Men. Then they step outside, trading the warmth and modern conveniences of a science station (foosball, fitness center, 24-hour cafeteria) for a minus-100-degree Fahrenheit featureless landscape, flatter than Kansas and one of the coldest places on the planet. They trudge in darkness nearly a mile, across a plateau of snow and ice, until they discern, against the backdrop of more stars than any hands-in-pocket backyard observer has ever seen, the silhouette of the giant disk of the South Pole Telescope, where they join a global effort to solve possibly the greatest riddle in the universe: what most of it is made of.From This Story
*This image is copyright of its original author
Photo Gallery Related Content
For thousands of years our species has studied the night sky and wondered if anything else is out there. Last year we celebrated the 400th anniversary of Galileo’s answer: Yes. Galileo trained a new instrument, the telescope, on the heavens and saw objects that no other person had ever seen: hundreds of stars, mountains on the Moon, satellites of Jupiter. Since then we have found more than 400 planets around other stars, 100 billion stars in our galaxy, hundreds of billions of galaxies beyond our own, even the faint radiation that is the echo of the Big Bang.Now scientists think that even this extravagant census of the universe might be as out-of-date as the five-planet cosmos that Galileo inherited from the ancients. Astronomers have compiled evidence that what we’ve always thought of as the actual universe—me, you, this magazine, planets, stars, galaxies, all the matter in space—represents a mere 4 percent of what’s actually out there. The rest they call, for want of a better word, dark: 23 percent is something they call dark matter, and 73 percent is something even more mysterious, which they call dark energy.“We have a complete inventory of the universe,” Sean Carroll, a California Institute of Technology cosmologist, has said, “and it makes no sense.”Scientists have some ideas about what dark matter might be—exotic and still hypothetical particles—but they have hardly a clue about dark energy. In 2003, the National Research Council listed “What Is the Nature of Dark Energy?” as one of the most pressing scientific problems of the coming decades. The head of the committee that wrote the report, University of Chicago cosmologist Michael S. Turner, goes further and ranks dark energy as “the most profound mystery in all of science.”The effort to solve it has mobilized a generation of astronomers in a rethinking of physics and cosmology to rival and perhaps surpass the revolution Galileo inaugurated on an autumn evening in Padua. They are coming to terms with a deep irony: it is sight itself that has blinded us to nearly the entire universe. And the recognition of this blindness, in turn, has inspired us to ask, as if for the first time: What is this cosmos we call home?Scientists reached a consensus in the 1970s that there was more to the universe than meets the eye. In computer simulations of our galaxy, the Milky Way, theorists found that the center would not hold—based on what we can see of it, our galaxy doesn’t have enough mass to keep everything in place. As it rotates, it should disintegrate, shedding stars and gas in every direction. Either a spiral galaxy such as the Milky Way violates the laws of gravity, or the light emanating from it—from the vast glowing clouds of gas and the myriad stars—is an inaccurate indication of the galaxy’s mass.But what if some portion of a galaxy’s mass didn’t radiate light? If spiral galaxies contained enough of such mystery mass, then they might well be obeying the laws of gravity. Astronomers dubbed the invisible mass “dark matter.”“Nobody ever told us that all matter radiated,”Vera Rubin, an astronomer whose observations of galaxy rotations provided evidence for dark matter, has said. “We just assumed that it did.”The effort to understand dark matter defined much of astronomy for the next two decades. Astronomers may not know what dark matter is, but inferring its presence allowed them to pursue in a new way an eternal question: What is the fate of the universe?Read more: http://www.smithsonianmag.com/science-nature/dark-energy-the-biggest-mystery-in-the-universe-9482130/#3CBxXSlsXplweD2Z.99
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http://www.smithsonianmag.com/science-nature/dark-energy-the-biggest-mystery-in-the-universe-9482130/?no-ist
RE: The Universe? - Pckts - 10-14-2014
There are over 10,000 near-Earth objects (NEOs) that have been identified so far — asteroids and comets of varying sizes that approach the Earth’s orbital distance to within about 28 million miles (45 million km). Of the 10,000 discoveries, roughly 10 percent are larger than six-tenths of a mile (one kilometer) in size — large enough to have disastrous global consequences should one impact the Earth.This is one of them.First discovered in February 1950, 1950 DA is a 1.1-kilometer-wide asteroid that was observed for 17 days and then disappeared from view. Then it was spotted again on Dec. 31, 2000 — literally on the eve of the 21st century. Coupled with radar observations made a few weeks later in March 2001 it was found that, along with a rather high rotation rate (2.1 hours), asteroid 1950 DA has a trajectory that will bring it very close to Earth on March 16, 2880. How close? Close enough that, within a specific 20-minute window, a collision can not be entirely ruled out.Top 10 Ways to Stop an AsteroidThe image above was made from radar observations by the Arecibo Observatory in Puerto Rico in March 2001, when 1950 DA passed within 7.8 million kilometers (4.8 million miles) of Earth. Is this the mug shot of a future continent-killer?Radar analysis and research of 1950 DA performed by NASA’s Jet Propulsion Laboratory scientists J.D. Giorgini, S. J. Ostro, Don Yeomans and several others from JPL and other institutions revealed that the impact probability from 1950 DA in March 2880 is, at most, 1 in 300 based on what is known about the asteroid so far.1 in 300 may sound like a slim chance, but actually this represents a risk 50% greater than that of the average hazard due to all other asteroids from now to then. However, that’s a maximum value. The study also noted the collision probability for 1950 DA as being in the range from 0 to 0.33%. That upper limit could increase or decrease as more is learned about the asteroid. (The next opportunity for studying 1950 DA via radar is in 2032.)There are many factors that influence the path of an asteroid through space. Its spin rate, reflectivity (albedo), composition, mass, terrain variations… gravitational interactions with other bodies, some of which may not even have been discovered yet… all of these can affect the movement of an asteroid and, more specifically, its exact position at a future point in time. While many of these things still aren’t precisely known for 1950 DA, one in particular could end up being the saving grace for our descendants: the Yarkovsky effect.PHOTOS: Russian Meteor Strike AftermathA small but important force acting upon asteroids, the Yarkovsky effect is a “nudge” created by thermal emission. As an asteroid gathers heat energy from the sun, it releases some of that energy back into space. Thanks to Newtonian mechanics the sheer act of doing so creates a physical push back on the asteroid itself, altering its course ever so slightly. Over a long span of time, this slight alteration could result in the relocation of 1950 DA away from the spot in space where Earth will be on March 16, 2880… at least enough so that a miss is certain.
*This image is copyright of its original author
Frame from an animation of 1950 DA rotating. CLICK HERE TO PLAYIn fact, recent research by JPL scientists D. Farnocchia and S.R. Chesley have taken into consideration the Yarkovsky effect on 1950 DA based on known values from previous observations, as well as new research suggesting that the asteroid has a retrograde rotation. While their latest assessment does put the risk of an impact in 2880 within the lower end of the probability spectrum (4×10^-4, or -0.58 on the Palermo Scale) it is still far from zero, and in fact remains higher than any other known potential impacts.PHOTOS: NASA’s Asteroid Capture MissionSo what would happen if the half-mile-wide 1950 DA were to hit Earth? While that depends on a lot of things, such as its composition, speed, angle of impact, where it impacts, etc., needless to say it would cause a lot of damage across a large area. I’m talking an energy release upwards of half a million megatons, which, were it to strike say, New York City, everything within at least a 100-mile radius would be flattened by the force of the impact alone — that’s halfway to Boston and Washington, DC (source). And that’s not even taking into consideration the air blast, atmospheric dust cloud, secondary impacts from debris, or damage from any resulting tsunami (if the impact were in the ocean)… the destruction would easily extend out many more hundreds of miles, and the repercussions — physical, financial, economic, and emotional — would extend around the globe.Put it this way: if a 40-meter object could do this, imagine what a 1-kilometer one would do.But again, precisely where 1950 DA will be in another 866 1/2 years (and whether or not it will occupy the same point in space as our planet) relies on many factors that aren’t well known — even though its orbit is pretty well understood. More in-depth observations will need to be made, and that is why asteroids like this must be carefully — and continually — watched.Luckily, 35 generations offers plenty of time to improve our knowledge. According to JPL’s Near-Earth Object program, “If it is eventually decided 1950 DA needs to be diverted, the hundreds of years of warning could allow a method as simple as dusting the surface of the asteroid with chalk or charcoal, or perhaps white glass beads, or sending a solar sail spacecraft that ends by collapsing its reflective sail around the asteroid. These things would change the asteroids reflectivity and allow sunlight to do the work of pushing the asteroid out of the way.”ANALYSIS: Meet Asteroid 2013 MZ5, 10,000th Near-Earth ObjectStill, whether because of ongoing research, faith in future generations of scientists, or just sheer probability, JPL remains confident that 1950 DA should cause little concern. “The most likely result will be that St. Patrick’s Day parades in 2880 will be a little more festive than usual as 1950 DA recedes into the distance, having passed Earth by.”Let’s just hope the luck of the Irish is with our planet big time that year…Source: JPL’s Near-Earth Object site. From an article originally posted on LightsInTheDark.com.Learn more about ongoing NEO research on the JPL site here, and find out about asteroid-hunting programs like NASA’s repurposed WISE spacecraft and the proposed Sentinel spacecraft from the B612 Foundation. Because in order to learn more about NEOs, we first need to find them (and there are a lot more out there where 1950 DA came from!)http://news.discovery.com/space/asteroids-meteors-meteorites/meet-the-asteroid-that-might-hit-earth-in-2880-131008.htm
RE: The Universe? - Pckts - 10-22-2014
Mars Suffers a Huge Comet Explosion
http://www.break.com/video/mars-suffers-a-huge-comet-explosion-2779270
RE: The Universe? - Pckts - 11-13-2014
10 surprising Lunar Facts
http://www.space.com/19619-top-10-moon-facts.html
10. The moon was created when a rock the size of Mars slammed into Earth, shortly after the solar system began forming about 4.5 billion years ago, according to the leading theory.
9.Perhaps the coolest thing about the moon is that it always shows us the same face. Since both the Earth and moon are rotating and orbiting, how can this be?
Long ago, the Earth's gravitational effects slowed the moon's rotation about its axis. Once the moon's rotation slowed enough to match its orbital period (the time it takes the moon to go around Earth) the effect stabilized. Many of the moons around other planets behave similarly.
What about phases? Here's how they work: As the moon orbits Earth, it spends part of its time between us and the Sun, and the lighted half faces away from us. This is called a new moon. (So there's no such thing as a "dark side of the moon," just a side that we never see.)
As the moon swings around on its orbit, a thin sliver of reflected sunlight is seen on Earth as a crescent moon. Once the Moon is opposite the Sun, it becomes fully lit from our view — a full moon. 8.More than 400 trees on Earth came from the moon. Well, okay: They came from lunar orbit. Okay, the truth: In 1971, Apollo 14 astronaut Stuart Roosa took a bunch of seeds with him and, while Alan Shepard and Edgar Mitchell were busy sauntering around on the surface, Roosa guarded his seeds.
Later, the seeds were germinated on Earth, planted at various sites around the country, and came to be called the moon trees. Most of them are doing just fine. More Than One Moon?
7.The moon is Earth's only natural satellite. Right? Maybe not. In 1999, scientists found that a 3-mile- (5-kilometer-) wide asteroid may be caught in Earth's gravitational grip, thereby becoming a satellite of our planet.
Cruithne, as it is called, takes 770 years to complete a horseshoe-shaped orbit around Earth, the scientists say, and it will remain in a suspended state around Earth for at least 5,000 years.
6.The moon is Earth's only natural satellite. Right? Maybe not. In 1999, scientists found that a 3-mile- (5-kilometer-) wide asteroid may be caught in Earth's gravitational grip, thereby becoming a satellite of our planet.
Cruithne, as it is called, takes 770 years to complete a horseshoe-shaped orbit around Earth, the scientists say, and it will remain in a suspended state around Earth for at least 5,000 years.
5.The moon is not round (or spherical). Instead, it's shaped like an egg. If you go outside and look up, one of the small ends is pointing right at you. And the moon's center of mass is not at the geometric center of the satellite; it's about 1.2 miles (2 kilometers) off-center.
4.Apollo astronauts used seismometers during their visits to the moon and discovered that the gray orb isn't a totally dead place, geologically speaking. Small moonquakes, originating several miles (kilometers) below the surface, are thought to be caused by the gravitational pull of Earth. Sometimes tiny fractures appear at the surface, and gas escapes.
Scientists say they think the moon probably has a core that is hot and perhaps partially molten, as is Earth's core. But data from NASA's Lunar Prospector spacecraft showed in 1999 that the moon's core is small — probably between 2 percent and 4 percent of its mass. This is tiny compared with Earth, in which the iron core makes up about 30 percent of the planet's mass.
3.Our moon is bigger than Pluto. And at roughly one-fourth the diameter of Earth, some scientists think the moon is more like a planet. They refer to the Earth-moon system as a "double planet." Pluto and its moon Charon are also called a double-planet system by some.
2.Tides on Earth are caused mostly by the moon (the Sun has a smaller effect). Here's how it works:
The moon's gravity pulls on Earth's oceans. High tide aligns with the Moon as Earth spins underneath. Another high tide occurs on the opposite side of the planet because gravity pulls Earth toward the moon more than it pulls the water.
At full moon and new moon, the Sun, Earth and moon are lined up, producing the higher than normal tides (called spring tides, for the way they spring up). When the moon is at first or last quarter, smallerneap tides form. The Moon's 29.5-day orbit around Earth is not quite circular. When the moon is closest to Earth (called its perigee), spring tides are even higher, and they're called perigean spring tides.
All this tugging has another interesting effect: Some of Earth's rotational energy is stolen by the moon, causing our planet to slow down by about 1.5 milliseconds every century.
1.As you read this, the moon is moving away from us. Each year, the moon steals some of Earth's rotational energy, and uses it to propel itself about 3.8 centimeters higher in its orbit. Researchers say that when it formed, the moon was about 14,000 miles (22,530 kilometers) from Earth. It's now more than 280,000 miles, or 450,000 kilometers away.
RE: The Universe? - Pckts - 11-13-2014
Interstellars extremely accurate depiction of a Black Hole
http://www.break.com/video/interstellar-s-blackhole-is-scientifically-accurate-2785691