12269'Cosmos: A Spacetime Odyssey' --Episode 3 In-Depth Preview (Sunday March 23
- Mar 22 3:35 PMfyi
Sent: 3/22/2014 6:09:06 P.M. Eastern Daylight Time
Subj: The Daily Galaxy: News from Planet Earth & Beyond
Posted: 22 Mar 2014 11:27 AM PDT
There was a time, not so long ago, when natural events could only be understood as gestures of divine displeasure. We will witness the moment that all changed, but first--The Ship of the Imagination is in the brooding, frigid realm of the Oort Cloud, where a trillion comets wait, taking us on a hair-raising ride, chasing a single comet through its million-year plunge towards the Sun.Some scientists think that our sun may have a stealth companion that disturbs comets from the edge of the solar system — a giant planet with up to four times the mass of Jupiter, researchers suggest in the distant icy realm of the comet-birthing Oort cloud, which surrounds our solar system with billions of icy objects. The potential giant Jupiter would likely be a world so frigid it is difficult to spot, researchers said. It could be found up to 30,000 astronomical units from the sun. One AU is the distance between the Earth and the sun, about 93 million miles.
The giant planet is hidden in our Solar System according to scientists John Matese and Daniel Whitmire, from the University of Louisiana at Lafayette. According to the team, a colossus called Tyche is hidden in the Oort Cloud—the asteroid beehive that forms the outer shell of our home system, one light-year in radius. They claim that data already captured by NASA's Wide-field Infrared Survey Explorer proves its existence.
Matese and Whitmire are convinced that Tyche composed mostly of hydrogen and helium is very real orbiting 15,000 times farther from the Sun than Earth, orbiting the Sun with moons and rings and an athmosphere with clouds and storm systems similar to Jupiter with a mild temperature (-73ºC/-99.4ºF).
If Tyche's existence is confirmed, its Solar System planet status may not be debated that Tyche could be a planet born in another star system and captured by ours.
Many of the most well known comets, including Halley, Hale-Bopp and, most recently, McNaught, may have been born in orbit around other stars, according to a theory developed by an international team of astronomers in 2010 led by a scientist from the Southwest Research Institute in Boulder, Colo. The team used computer simulations to show that the Sun may have captured small icy bodies from its sibling stars while it was in its birth star cluster, creating a reservoir for observed comets.
While the Sun currently has no companion stars, it is believed to have formed in a cluster containing hundreds of closely packed stars that were embedded in a dense cloud of gas. During this time, each star formed a large number of small comets in a disk from which planets formed. Most of these comets were gravitationally slung out of these prenatal planetary systems by the newly forming giant planets, becoming tiny, free-floating members of the cluster.
The Sun's cluster came to a violent end, however, when its gas was blown out by the hottest young stars. These new models show that the Sun then gravitationally captured a large cloud of comets as the cluster dispersed.
"When it was young, the Sun shared a lot of spit with its siblings, and we can see that stuff today," says Dr. Hal Levison of the Southwest Research Institute.
Evidence for the team's scenario came from the roughly spherical cloud of comets, known as the Oort cloud, that surrounds the Sun, extending halfway to the nearest star. It has been commonly assumed this cloud formed from the Sun's proto-planetary disk. However, because detailed models show that comets from the solar system produce a much more anemic cloud than observed, another source is required.
"If we assume that the Sun's observed proto-planetary disk can be used to estimate the indigenous population of the Oort cloud," Levison says, "we can conclude that more than 90 percent of the observed Oort cloud comets have an extra-solar origin."
"The formation of the Oort cloud has been a mystery for over 60 years and our work likely solves this long-standing problem," says Brasser.
Just how safe is the Earth from a major comet impact event? Jupiter may hold the answer. On 1994 July 16-22, over twenty fragments of comet Shoemaker-Levy 9 collided with the planet Jupiter. The comet, discovered the previous year by astronomers Carolyn and Eugene Shoemaker and David Levy, was observed by astronomers at hundreds of observatories around the world as it crashed into Jupiter's southern hemisphere. During July, 2010 a comet or asteroid ripped another Pacific-Ocean sized hole in Jupiter (image below). Is Jupiter a giant protective magnet for Earth, or are these events wake-up calls similar to Friday's meteor explosion over Russia's Ural Mountains?
As Stephen Hawking says, the general consensus is that any comet or asteroid greater than 20 kilometers in diameter that strikes the Earth will result in the complete annihilation of complex life - animals and higher plants. (The asteroid Vesta, for example, one of the destinations of the Dawn Mission, is the size of Arizona).
Since 1941 many astronomers have thought of Jupiter as a protective big brother for planet Earth -a celestial shield, deflecting asteroids and comets away from the inner Solar System. This long-standing belief that Jupiter acts as a celestial shield, deflecting asteroids and comets away from the inner Solar System, has been challenged by the first in a series of studies evaluating the impact risk to the Earth posed by different groups of object.
Dr Jonathan Horner of Great Britain's Open University has studied the impact hazard posed to Earth by the Centaurs, the parent population of the Jupiter Family of comets. His research showed that the presence of a Jupiter-like planet in the Solar System does not necessarily lead to a lower impact rate at the Earth. Horner said that Jupiter's role as guardian may have been overstated: "It seems that the idea isn't so clear-cut."
The idea of Jupiter as protector was first proposed by planetary scientist George Wetherill in 1941. Wetherill showed that the planet's enormous mass — more than 300 times that of the Earth — is enough to catapult comets that might hit Earth, like a slingshot ,out of the Solar System.
Other astronomers have postulated that Jupiter's gravitational pull would thin the crowd of dangerous asteroids and other objects, making Earth less impact prone. Other research has suggested that, in the past, changes in Jupiter's orbit might have actually increased the number of objects on a collision course with earth. Until now, Horner says, little work was done to test either idea.
The short period Jupiter Family of Comets (JFCs) are believed to originate from the Kuiper Belt and have orbital periods of up to 20 years and low inclination controlled by Jupiter. The Kuiper Belt is a large reservoir of small icy bodies just beyond Neptune. From collisions or gravitational perturbations some Kuiper Belt objects escape and fall towards the Sun. When they approach the Sun their volatile elements will start to sublimate off the surface and we will see the object as a comet. Because the orbit crosses that of Jupiter, the comet will have gravitational interactions with this massive gas giant. The objects orbit will gradually change from these interactions and eventually the object will either be thrown out of the Solar System or collide with a planet or the Sun.
The second class of comets, the long periods, are believed to originate from the Oort cloud. This is a vast spherical reservoir believed to exist at the edge of the Solar System. The long period comets have periods of less than 200 years and no preference in orbital inclination.
"The idea that a Jupiter-like planet plays an important role in lessening the impact risk on potentially habitable planets is a common belief but there has only really been one study done on this in the past, which looked at the hazard due to the Long Period Comets," Horner continued." We are carrying out an ongoing series of studies of the impact risks in planetary systems, starting off by looking at our own Solar System, since we know the most about it."
Horner and colleague Barrie Jones built several versions of the Solar System on the Open University's computers: one with a Jupiter, one without, and several with a gas giant that was either a quarter, half, or three-quarters of Jupiter's mass. The system also contained 100,000 centaurs — large, icy bodies from the Solar System's Kuiper belt, within which Pluto lies.
After running their models for 10 million virtual years, Horner and Jones found some striking results:The Earth was about 30% more likely to be hit by a centaur in a Solar System with a life-size Jupiter than it was in a Jupiter-less system.
"We've found that if a planet about the mass of Saturn or a bit larger occupied Jupiter's place," Horner concluded, "then the number of impacts on Earth would increase. However if nothing was there at all, there wouldn't be any difference from our current impact rate. Rather than it being a clear cut case that Jupiter acts as a shield, it seems that Jupiter almost gives with one hand and takes away with the other!"
The weakness of Horner's tentative conclusion is that it fails to take into account Jupiter's ability to deflect Earth-colliding objects from the Oort cloud, a massive cloud of comets that surrounds the Solar System
The Open University team is assessing the impact risk posed to the Earth by the asteroids and will go on to study the long period comets, before examining the role of the position of Jupiter within our system.
But back to Stephen Hawking: How many times in our galaxy alone has life finally evolved to the equivalent of our planets and animals on some far distant planet, he asks, only to be utterly destroyed by an impact? Galactic history suggests it might be a common occurrence. Our cold comfort comes from the adjective "galactic" -that's a hugely different time perspective that our biblical three score and ten.
The Daily Galaxy via via Southwest Research Institute
Posted: 22 Mar 2014 02:36 PM PDT
Two hundred of the world's experts in the search for life beyond our solar system are meeting this week to probe the great unanswered question of the 21st Century: Are we alone in the universe? Motivated by the rapidly increasing number of known Earth-sized planets, the increasing range of extreme conditions in which life on Earth can persist, and the progress toward a technology that will ultimately enable the search for life on exoplanets, the Vatican Observatory and the Steward Observatory are holding a major conference this week entitled The Search for Life Beyond the Solar System: Exoplanets, Biosignatures & Instruments.The goal of the conference called "The Search for Life Beyond the Solar System: Exoplanets, Biosignature & Instruments," which runs from March 16 through 21 in Tucson, Ariz. is to bring together the interdisciplinary community required to address this multi-faceted challenge: experts on exoplanet observations, early and extreme life on Earth, atmospheric biosignatures, and planet-finding telescopes.
Astrobiologists attending the conference include John Baross (U. Washington), Natalie Batalha (NASA Ames), Phil Hinz (UA), Markus Kasper (ESO), Lynn Rothschild (NASA Ames), Lisa Kaltenegger (MPIA, CfA), Peter Lawson (NASA JPL), Sara Seager (MIT), and Jill Tarter (SETI)
"Finding life beyond Earth is one of the great challenges of modern science and we are excited to have the world leaders in this field together in Tucson," said event co-chair Daniel Apai, assistant professor of astronomy and planetary sciences at the UA Steward Observatory, in a statement. "But reaching such an ambitious goal takes planning and time. The goal of this meeting is to discuss how we can find life among the stars within the next two decades."
José Gabriel Funes, an Argentine Jesuit priest and astronomer, and the current director of the Vatican Observatory says there is no conflict between believing in God and in the possibility of extraterrestrial civilizations perhaps more evolved than humans.
"In my opinion this possibility exists," said the Reverend José Gabriel Funes, current director of the Vatican Observatory and a scientific adviser to Pope Benedict XVI, referring to life on other planets.
"How can we exclude that life has developed elsewhere," he said in an interview with the Vatican newspaper L'Osservatore Romano. The large number of galaxies with their own planets makes this possible, he noted.
Asked if he was referring to beings similar to humans or even more evolved than humans, he said: "Certainly, in a universe this big you can't exclude this hypothesis."
"Just as there is a multiplicity of creatures on earth, there can be other beings, even intelligent, created by God. This is not in contrast with our faith because we can't put limits on God's creative freedom. Why can't we speak of a 'brother extraterrestrial'? It would still be part of creation."
Funes, who runs the observatory that is based south of Rome and in Arizona, held out the possibility that the human race might actually be the "lost sheep" of the universe. There could be other beings "who remained in full friendship with their creator," he said.
Funes commentary is a giant step away from the historical record that includes the Inquisition, which condemned Galileo in the 17th century for insisting that the Earth revolved around the Sun. The Roman Catholic Church did not rehabilitate him until 1992.
Funes said he believed as an astronomer that the most likely explanation for the start of the universe was "the big bang," the theory that it sprang into existence from dense matter billions of years ago. But he said this was not in conflict with faith in God as creator. "God is the creator," he said. "There is a sense to creation. We are not children of an accident."
He added: "As an astronomer, I continue to believe that God is the creator of the universe and that we are not the product of something casual but children of a good father who has a project of love in mind for us."
NASA's Astrobiology Institute will broadcast a live feed of the sessions. You can learn more via the conference website: http://www.ebi2014.org/ http://www.ebi2014.org/
The Daily Galaxy via http://www.ebi2014.org/
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