HOW GREAT THOU ART
Saturday, December 19, 2009
Large Planet or Brown Dwarf Discovered
A New Planet (or Brown Dwarf?) Discovered
In December, an international team of astronomers announced it had spotted a planetlike object orbiting a star much like our sun. The star lies 300 trillion miles, or about 50 light-years, from Earth; the planetlike object is estimated to be 10 to 40 times the size of Jupiter. Using a new planet-hunting instrument on the Subaru telescope in Hawaii, scientists were able to get direct images of this new object — which may or may not be a brown dwarf (a failed star). Although direct images of other solar systems have been taken before, this is the first time astronomers have captured a star this similar to the sun in size and temperature. Scientists say the real surprise is the location of the orbit of GJ 758 B, as the newly identified object was dubbed: it was previously thought that large planets form either closer to or farther from their stars, but not in the location of GJ 758 B, which is about as far from its star as Neptune is from the sun. Alan Boss, an astronomer at the Carnegie Institute for Science who was not involved in the research, said the "beautiful detection of a very low-mass companion to a sunlike star reminds us again how little we truly know" about the planets around nearby stars.
Read more: http://www.time.com/time/specials/packages/article/0,28804,1945379_1944416_1944442,00.html?artId=1945379?contType=article?chn=specials#ixzz0a8oIwasr
Labels: large planet or brown dwarf discovered
Sunday, December 06, 2009
Iris Nebula
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Iris Nebula
http://en.wikipedia.org/wiki/iris_nebula| Iris Nebula | |
|---|---|
 Iris Nebula (NGC 7023 and LBN487) Courtesy Hunter Wilson | |
| Observation data: J2000.0 epoch | |
| Type | Reflection |
| Right ascension | 21h 01m 35.60s |
| Declination | +68° 10′ 10.0" |
| Distance | 1,300 ly |
| Apparent magnitude (V) | 6.8 |
| Apparent dimensions (V) | 18' x 18' |
| Constellation | Cepheus |
| Physical characteristics | |
| Radius | 3 ly |
| Other designations | NGC 7023 and LBN487, Caldwell 4 |
| See also: Diffuse nebula, Lists of nebulae | |
The Iris Nebula, also NGC 7023 and Caldwell 4, is a bright reflection nebula and Caldwell object in the constellation Cepheus. NGC 7023 is actually the cluster within the nebula, LBN 487, and the nebula is lit by a magnitude +7 star, SAO 19158.[1] It shines at magnitude +6.8. It is located near the Mira-type variable star T Cephei, and near the bright magnitude +3.23 variable star Beta Cephei (Alphirk). It lies 1,300 light-years away and is six light-years across.[2]
Labels: iris nebula
Thursday, November 26, 2009
Pillars of Creation
http://www.space.com/scienceastronomy/070109_toppled_pillars.html
http://www.nasa.gov/mission_pages/spitzer/multimedia/ssc2007-01b.html
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This majestic view taken by NASA's Spitzer Space Telescope tells an untold story of life and death in the Eagle nebula, an industrious star-making factory located 7,000 light-years away in the Serpens constellation. The image shows the region's entire network of turbulent clouds and newborn stars in infrared light.
The color green denotes cooler towers and fields of dust, including the three famous space pillars, dubbed the "Pillars of Creation," which were photographed by NASA's Hubble Space Telescope in 1995 (see inset). But it is the color red that speaks of the drama taking place in this region. Red represents hotter dust thought to have been warmed by the explosion of a massive star about 8,000 to 9,000 years ago. Since light from the Eagle nebula takes 7,000 years to reach us, this "supernova" explosion would have appeared as an oddly bright star in our skies about 1,000 to 2,000 years ago.
According to astronomers' estimations, the explosion's blast wave would have spread outward and toppled the three pillars about 6,000 years ago (which means we wouldn't witness the destruction for another 1,000 years or so). The blast wave would have crumbled the mighty towers, exposing newborn stars that were buried inside, and triggering the birth of new ones.
The pillars of the Eagle nebula were originally sculpted by radiation and wind from about 20 or so massive stars hidden from view in the upper left portion of the image. The radiation and wind blew dust away, carving out a hollow cavity (center) and leaving only the densest nuggets of dust and gas (tops of pillars) flanked by columns of lighter dust that lie in shadow (base of pillars). This sculpting process led to the creation of a second generation of stars inside the pillars.
If a star did blow up in this region, it is probably located among the other massive stars in the upper left portion of the image. Its blast wave might have already caused a third generation of stars to spring from the wreckage of the busted pillars.
This image is a composite of infrared light detected by Spitzer's infrared array camera and multiband imaging photometer. Blue is 4.5-micron light; green is 8-micron light; and red is 24-micron light.
Image credit: NASA/JPL-Caltech/ Institut d'Astrophysique Spatiale
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Labels: pillars of creation
Saturday, November 14, 2009
Did Future Sabotage Hadron Collider?
http://www.time.com/time/health/article/0,8599,1937370,00.html
Did a Time-Traveling Bird Sabotage the Collider?
Sometime on Nov. 3, the supercooled magnets in sector 81 of the Large Hadron Collider (LHC), outside Geneva, began to dangerously overheat. Scientists rushed to diagnose the problem, since the particle accelerator has to maintain a temperature colder than deep space in order to work. The culprit? "A bit of baguette," says Mike Lamont of the control center of CERN, the European Organization for Nuclear Research, which built and maintains the LHC. Apparently, a passing bird may have dropped the chunk of bread on an electrical substation above the accelerator, causing a power cut. The baguette was removed, power to the cryogenic system was restored and within a few days the magnets returned to their supercool temperatures.
While most scientists would write off the event as a freak accident, two esteemed physicists have formulated a theory that suggests an alternative explanation: perhaps a time-traveling bird was sent from the future to sabotage the experiment. Bech Nielsen of the Niels Bohr Institute in Copenhagen and Masao Ninomiya of the Yukawa Institute for Theoretical Physics in Kyoto, Japan, have published several papers over the past year arguing that the CERN experiment may be the latest in a series of physics research projects whose purposes are so unacceptable to the universe that they are doomed to fail, subverted by the future. (See pictures of the Large Hadron Particle Collider.)
The LHC, a 17-mile underground ring designed to smash atoms together at high energies, was created in part to find proof of a hypothetical subatomic particle called the Higgs boson. According to current theory, the Higgs is responsible for imparting mass to all things in the universe. But ever since the British physicist Peter Higgs first postulated the existence of the particle in 1964, attempts to capture the particle have failed, and often for unexpected, seemingly inexplicable reasons.
In 1993, the multibillion-dollar United States Superconducting Supercollider, which was designed to search for the Higgs, was abruptly canceled by Congress. In 2000, scientists at a previous CERN accelerator, LEP, said they were on the verge of discovering the particle when, again, funding dried up. And now there's the LHC. Originally scheduled to start operating in 2006, it has been hit with a series of delays and setbacks, including a sudden explosion between two magnets nine days after the accelerator was first turned on, the arrest of one of its contributing physicists on suspicion of terrorist activity and, most recently, the aerial bread bombardment from a bird. (A CERN spokesman said power cuts such as the one caused by the errant baguette are common for a device that requires as much electricity as the nearby city of Geneva, and that physicists are confident they will begin circulating atoms by the end of the year). (See the top 10 animal stories of 2008.)
In a series of audacious papers, Nielsen and Ninomiya have suggested that setbacks to the LHC occur because of "reverse chronological causation," which is to say, sabotage from the future. The papers suggest that the Higgs boson may be "abhorrent to nature" and the LHC's creation of the Higgs sometime in the future sends ripples backward through time to scupper its own creation. Each time scientists are on the verge of capturing the Higgs, the theory holds, the future intercedes. The theory as to why the universe rejects the creation of Higgs bosons is based on complex mathematics, but, Nielsen tells TIME, "you could explain it [simply] by saying that God, in inverted commas, or nature, hates the Higgs and tries to avoid them."
Many physicists say that Nielsen and Ninomiya's theory, while intellectually interesting, cannot be accurate because the event that the LHC is trying to recreate already happens in nature. Particle collisions of an energy equivalent to those planned in the LHC occur when high-energy cosmic rays collide with the earth's atmosphere. What's more, some scientists believe that the Tevatron accelerator at Fermi National Accelerator Laboratory (or Fermilab) near Chicago has already created Higgs bosons without incident; the Fermilab scientists are now refining data from their collisions to prove the Higgs' existence. (See the top 10 scientific discoveries of 2008.)
Nielsen counters that nature might allow a small number of Higgs to be produced by the Tevatron, but would prevent the production of the large number of particles the LHC is anticipated to produce. He also acknowledges that Higgs particles are probably produced in cosmic collisions, but says it's impossible to know whether nature has stopped a great deal of these collisions from happening. "It's possible that God avoids Higgs [particles] only when there are very many of them, but if there are a few, maybe He let's them go," he says.
Nielsen and Ninomiya's theory represents one side of an intellectual divide between particle physicists today. Contemporary physicists tend to fall into one of two camps: the theorists, who posit ideas about the origins and workings of the universe; and experimentalists, who design telescopes and particle accelerators to test these theories, or provide new data from which novel theories can emerge. Most experimentalists believe that the theorists, due to a lack of new data in recent years, have reached a roadblock — the Standard Model, which is the closest thing the theorists have to an evidence-backed "theory of everything," provides only an incomplete explanation of the universe. Until theorists get further data and evidence to move forward, the experimentalists believe, they end up simply making wild guesses — like those concerning time-traveling saboteurs — about how the universe works. "Nielsen and Ninomiya's theories are clearly crazy theories," says Dmitri Denisov, a physicist and Higgs-hunter at the DZero experiment at Fermilab. "In recent years theorists have been starving for experimental input and as a result, theories of second type are propagating widely. The majority of them have nothing to do with world we live in." (See the best inventions of 2008.)
Nielsen concedes, "We have very little data, so theorists are going their own ways and making a lot of theories that may not be very plausible. We need guidance from experimentalists to make the theories more healthy."
"But," he adds, "in terms of our theory, we are submitting to a form of experiment. We are saying the LHC won't be allowed to produce a large number of Higgs. If it does, it would be very damaging to our theory."
Particle physics has a long history of zany theories that turned out to be true. Niels Bohr, the doyen of modern physicists, often told a story about a horseshoe he kept over his country home in Tisvilde, Denmark. When asked whether he really thought it would bring good luck, he replied, "Of course not, but I'm told it works even if you don't believe in it." In other words: if preposterous theories are mathematically sound and can be confirmed by observation, they are true, even if seemingly impossible to believe. To scientists in the early 20th century, for example, quantum mechanics may have seemed outrageous. "The concept that you could have a wave-particle duality — that an object could take on either wave-like properties or point-like properties, depending on how you observe it — takes a huge leap of imagination," says Roberto Roser, a scientist at Fermilab. "Sometimes outlandish papers turn out to be the laws of physics."
So what would Peter Higgs himself make of the intellectual controversy surrounding his eponymous particle? Speaking on behalf of his friend, Professor Richard Kenway, who holds Higgs' former position at the University of Edinburgh, says that the 78-year-old emeritus professor remains quietly confident that the LHC will discover the Higgs boson when it is eventually running at full strength. For his part, Kenway says the LHC's delays are to be expected given the size and intricacy of the $9 billion experiment. And he says if he ever needs further proof that the Higgs boson is not abhorrent to nature, he need only spend time with his friend and mentor. "If nature truly did not want us to discover the Higgs, a cosmic ray would have zapped the embryo that became Peter, preventing its development into a physicist," he says.
Read more: http://www.time.com/time/health/article/0,8599,1937370,00.html#ixzz0Wr0O83Ak
Labels: hadron collider - sabotaged?
Saturday, October 31, 2009
Do We Have Neighbors?
32 New Planets Found Outside Our Solar System
Astronomers have added 32 new planets to the list of planets found orbiting stars outside our solar system.
The discoveries, announced today at a press briefing in Portugal, increase to more than 400 the number of known extrasolar planets, or "exoplanets."
The 32 previously unseen planets range from five times the mass of Earth up to eight times the mass of Jupiter, scientists said.
In addition, the new planets were found around different types of stars, challenging existing theories for where and how planets form.
Overall, the research suggests that 40 to 60 percent of all planetary systems in the universe contain low-mass planets.
Since lower masses most likely mean Earthlike sizes, such planets are considered to be the best candidates in the search for extraterrestrial life. (Related pictures: "3 Worlds Most Likely to Harbor Life Named.")
"The models are predicting even larger numbers of low-mass planets like Earth, so I am pretty confident that there are Earth-type planets everywhere," said team member Stephane Udry of the Observatory of Geneva in Switzerland.
"Nature doesn't like a vacuum," he added, "so if there is space to put a planet, it will put the planet there."
New Planets: Super-Earths, Gas Giants
The 32 new planets were found over the past five years using an instrument called a spectrograph at the European Southern Observatory in La Silla, Chile.
Known as HARPS, for High Accuracy Radial velocity Planetary Searcher, the spectrograph detects wobbles in a star's orbit caused by the pull of an unseen exoplanet.
The HARPS team selected stars like our sun, as well as lower-mass dwarf stars, to watch for wobbles.
Red dwarf stars were targets because they are dimmer, low-mass stars, which makes it easier to detect wobbles from low-mass satellite planets, said team member Nuno Santos, of the University of Porto, Portugal.
The 32 newfound exoplanets include several super-Earths, such as two planets no more than five times Earth's mass and two about six times Earth's mass, the Observatory of Geneva's Udry said.
The largest newly discovered exoplanet is a monster at seven to eight times Jupiter's mass, he estimated.
In addition, several Jupiter-mass planets were found around stars that don't have many metals.
Previous theories had stated that planets wouldn't tend to form around metal-poor stars, since planets are thought to take shape inside the metal-filled disks of debris left over from stellar birth.
The new finds suggest that astronomers might need to revise theories of planet formation—and may increase the number of possible star systems in the universe.
(Related: "Turbulence Key to Planet Formation, New Study Suggests.")
Exact details about each of the 32 new planets have yet to be published, Udry said, but "a bunch of the new planets will be described in the next six months."
Planets and Habitability: The Next Step
Counting the 32 new planets, the HARPS instrument has so far helped astronomers find 75 of the roughly 400 known exoplanets.
For example, a team using HARPS had previously found several low-mass planets orbiting Gliese 581, a red dwarf star some 20.5 light-years away.
One of these planets, Gliese 581 c, has been touted as the first Earthlike planet yet found outside the solar system.
But for most of the newly revealed exoplanets, appraisals of their habitability will probably have to wait, the team said.
"It will be very difficult to confirm a planet detected [by HARPS] is the size of the Earth and that it would also be in the habitable zone," Udry said.
"We need the next generation of radio-velocity machine to do that," he said, adding that such a device should be ready in the next five years.
---Labels: 32 exoplanets found
Sunday, October 25, 2009
Earthlike Planet Found-May Have Liquid Water
Astronomers also announced that one of the system's other planets, Gliese 581d, is an Earthlike world that orbits in the right zone to host liquid water, and thus potentially life.
Image courtesy ESO/L. Calçada
earthlike planet - liquid water
http://news.nationalgeographic.co.uk/news/2009/04/090421-most-earthlike-planet.html?sms_ss=email
Most Earthlike Planet Yet Found May Have Liquid Oceans
It probably wouldn't feel exactly like home. But the planet known as Gliese 581d has a lot more in common with Earth than astronomers first thought.
New measurements of the planet's orbit place it firmly in a region where conditions would be right for liquid water, and thus life as we know it, astronomer Michel Mayor, from Geneva University in Switzerland, announced today.
"It lies in the [life-supporting] habitable zone, and it could have an ocean at its surface," Mayor said during the European Week of Astronomy and Space Science conference, being held this week at the University of Hertfordshire in the U.K.
First discovered in 2007, Gliese 581d was originally calculated to be too far away from its host star—and therefore too cold—to support an ocean.
But Mayor and colleagues now show that the extrasolar planet, or exoplanet, orbits its host in 66.8 days, putting it just inside the cool star's habitable zone.
At the same time, Mayor and colleagues announced that they have spotted a fourth planet orbiting in the Gliese 581 star system—and it's the lightest exoplanet found so far.
The planet, dubbed Gliese 581e, is only about twice the mass of Earth and is the closest planet to the star, completing its orbit in about 3.15 days.
"It brings down the mass [of the lightest known exoplanet] by more than a factor of two. The previous smallest was around five Earth masses," said Andrew Collier Cameron, an astronomer at the University of Saint Andrews in the U.K. who was not involved in the find.
(Related: "Mysterious 'Super Earth' Is Smallest Known Exoplanet?")
Near Neighbor
Gliese 581, a red dwarf star in the constellation Libra, lies around 20.5 light-years from Earth.
"In astronomical terms it is one of our near neighbors, the 87th closest known star system to the sun," said Carole Haswell, an astronomer at the Open University in Milton Keynes, U.K.
Since planets orbiting Gliese 581 are too far away to be seen directly, Mayor and colleagues originally spotted Gliese 581d by searching for tiny wobbles in the host star's motion using the European Southern Observatory (ESO) telescope at La Silla in Chile.
Weighing in at around seven Earth masses, Gliese 581d is unlikely to be made of rocks alone, the team believes.
"We can only speculate at this stage, but it may have a rocky core, encased in an icy layer, with a liquid ocean at the surface and an atmosphere," Mayor said.
Meanwhile, the much smaller and lighter Gliese 581e "probably doesn't look too different to Earth, except that it will be very hot, because it is so close to its host star," said Andrew Norton, an astronomer also at the Open University.
Norton's colleague Haswell added: "It is very exciting that such a promising candidate for an Earthlike planet has been found so close to us. It means there are likely to be many more when we search further."
And the more Earthlike planets there are, the greater the chance of discovering one that harbors life.
"I think it is only a matter of time," Norton said. "If life really does exist elsewhere in the universe, then within the next 10 to 15 years I expect we may see the first signs of life, via spectroscopic signals from exoplanets."
Labels: earthlike planet - maybe life
Friday, October 02, 2009
The Never-Ending Dream of Flight
The Never-Ending Dream of Flight
- Tales from the complex history of the moon race.
ABC News coverage of Apollo 11, the 40th anniversary of the historic moon ... WATCH: The Never-Ending Dream of Flight. WATCH: 'I Called the Moon My Home' ...
Apollo: 'One Giant Leap'? Or a Waste of Money?
40 years after Neil Armstrong's moonwalk, the debate goes on.
How Did Moon Travel Change Astronauts?
For some, going to the moon changed the course of their lives.
Debunking Moon Landing Hoax Theories
A review of so-called evidence suggesting the Apollo 11 never reached the moon.
Photos: Where Are The Moonwalkers Now?
What happens after the mission of a lifetime?
After Apollo: Water on the Moon?
NASA probe, 40 years after Apollo, to make a splash if it finds frozen deposits.
Stars and Stripes: Putting the Flag on the Moon
The story of how NASA planted that famous flag on the moon......................................
To View 3 main videos, click on abcnews.go.com/Technology/apollo11moonlanding
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WATCH: Buzz Aldrin on the Dangers of Apollo 11
The first journey to the moon was especially risky (July 7, 1997).WATCH: Was Moon Mission a Step Forward?
WATCH: Breakdown of Apollo 11
WATCH: 1969 Profile of Neil Armstrong
ABC's Frank Reynolds talks about the life of the Apollo 11 commander.WATCH: The Buzz About Moon Walking
WATCH: 'I Called the Moon My Home'
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Labels: never ending dream of flight
Coldest Place in Solar System
http://news.rediff.com/report/2009/sep/28/moon-not-pluto-the-coldest-in-solar-system.htm
Dark craters near Moon's [ Images ] south pole may be the coldest place in the entire solar system, frostier than planet Pluto. The crater floors which are 239,000 miles down, have 'daytime' temperatures that never rise above minus 400 degrees Fahrenheit, according to preliminary results from NASA's [ Images ] Lunar Reconnaissance Orbiter.
The super-cold temperatures are chilly enough to have preserved ice for billions of years in the craters, according to NASA scientists.
"This is an exciting time for LRO," Richard Vondrak, who heads the solar-system exploration division at the Goddard Space Flight Institute in Greenbelt was quoted by Christian Science Monitor.
The data released said that the thermal measurements showed daytime temperature over much of the Moon's surface reach 220 degree Fahrenheit, which is hotter than boiling water before plummeting to frigidness at night.
While, the temperatures in the dark craters which never saw sunlight remained below minus 400 degrees Fahrenheit making them solar system's coldest areas.
Pluto is currently considered the coldest planet with minimum temperature ranging fron minus 391 to minus 346 degree Fahrenheit.
Launched in June, the orbiter on a one year mission officially began its mapping mission last week, orbiting the Moon some 30 miles above the surface.
Labels: cold moon
wild weather - our galaxy
http://www.space.com/scienceastronomy/060703_wild_weather_top10.html
For decades, astronomers have been using telescopes to decipher atmospheric conditions on distant worlds. From 1,500-mph winds on Neptune to scorching heat waves on Venus and even worse weather on huge worlds beyond our solar system, you'll be glad you live on Earth.
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Labels: wild weather - our galaxy
Thursday, September 17, 2009
Bizzare Faraway Galaxies
Speeding Stars Confirm Bizarre Nature of Faraway Galaxies
By Clara Moskowitz, Staff Writer
posted: 05 August 2009 01:03 pm ET
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Stars in a distant galaxy move at stunning speeds — greater than 1 million mph, astronomers have revealed.
These hyperactive stars move at about twice the speed of our sun through the Milky Way, because their host galaxy is very massive, yet strangely compact. The scene, which has theorists baffled, is 11 billion light-years away. It is the first time motions of individual stars have been measured in a galaxy so distant.
While the stars' swiftness is notable, stars in other galaxies have been observed to travel at similarly high speeds. In those situations, it was usually because they were interlopers from outside, or circling close to a black hole.
But in this case, the stars' high velocities help astronomers confirm that the galaxy they belong to really is as massive as earlier data suggested.
Bizarre, indeed
The compact nature of this and similar galaxies in the faraway early universe is puzzling to scientists, who don't yet understand why some young, massive galaxies are about five times smaller than their counterparts today.
"A lot of people were thinking we had overestimated these masses in the past," said Yale University astronomer Pieter van Dokkum, leader of the new study. "But this confirms they are extremely massive for their size. These galaxies are indeed as bizarre as we thought they were."
Scientists used the new velocity measurements, conducted with the Gemini South telescope in Chile and the Hubble Space Telescope, to test the mass of a galaxy identified as 1255-0. The same way that the sun's gravity determines the orbiting speed of the Earth, the galaxy's gravity, and thus its mass, determines the velocities of the stars inside it.
The researchers found that indeed, the galaxy is exceptionally dense.
Given its distance of 11 billion light-years, galaxy 1255-0 is seen as it existed 11 billion years ago, less than 3 billion years after the theoretical Big Bang. Among other galaxies we can observe from this time period, about 30 to 40 percent are compact like this one. But in the modern, nearby universe, astronomers don't find anything similar.
Something wrong?
Somehow, high-mass galaxies from the young universe grow in size but not in mass – they spread out but maintain their overall heft – to become the high-mass galaxies we see today.
"It's a bit of a puzzle," van Dokkum told SPACE.com. "We think these galaxies must grow through collisions with other galaxies. The weird thing is that these mergers must lead to galaxies that are larger in size but not much more massive. We need a mechanism that grows them in size but not in mass."
So far, such a mechanism is elusive, but astronomers have some ideas. Perhaps these galaxies expand their girth by merging with many small, low-mass galaxies. Or maybe these galaxies eventually become the dense central regions of even larger galaxies.
"It could also still be that we are doing something wrong," van Dokkum said. "But I think at the moment you could say that the ball is somewhat in the court of the theorists. Hopefully they can come up with some kind of explanation that we can test further."
Labels: bizzare faraway galaxies
Tuesday, August 11, 2009
Lost Planet - Birth of Moon
Also see:http://how-great-thou.blogspot.com/2007/03/universe-gives-us-our-moon.html
[earlier theory]
The Search for the Solar System's Lost Planet
By Clara Moskowitz
Staff Writer
posted: 13 April 2009
09:42 am ET
The solar system might once have had another planet named Theia, which may have helped create our own planet's moon.
Now two spacecraft are heading out to search for leftovers from this rumored sibling, which would have been destroyed when the solar system was still young.
"It's a hypothetical world. We've never actually seen it, but some researchers believe it existed 4.5 billion years ago — and that it collided with Earth to form the moon," said Mike Kaiser, a NASA scientist at the Goddard Space Flight Center in Maryland.
Theia is thought to have been about Mars-sized. If the planet crashed into Earth long ago, debris from the collision could have clumped together to form the moon. This scenario was first conceived by Princeton scientists Edward Belbruno and Richard Gott.
Many researchers now figure that indeed some large object crashed into Earth, and the resulting debris coalesced to form the moon. It is unclear though if that colliding object was a planet, asteroid or comet.
In any case, the debris that would have spun out from the two slamming bodies would have mixed together, and could explain some aspects of the moon's geology, such as the size of the moon's core and the density and composition of moon rocks.
http://www.space.com/common/media/video/player.php?videoRef=071120TugMoon
Scientists are hoping NASA's twin STEREO probes, launched in 2006, will be able to discover leftover traces of Theia that may finally help close the case on the birth of our moon.
So far, signs of Theia have proved elusive to telescopes searching from Earth. But the STEREO spacecraft are set to enter special points in space, called Lagrangian points, where the gravity from the Earth and the sun combine to form wells that tend to collect solar system detritus. [Click here for an animation that explains Lagrangian points.]
http://www.space.com/scienceastronomy/moon_formation_040621.html
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"The STEREO probes are entering these regions of space now," Kaiser, a STEREO project scientist, said. "This puts us in a good position to search for Theia's asteroid-sized leftovers."
By visiting the Lagrangian points directly, STEREO will be able to hunt for Theia chunks up close. The nearest approach to the bottoms of the gravitational wells will come in September and October 2009.
"STEREO is a solar observatory," Kaiser said. "The two probes are flanking the sun on opposite sides to gain a 3-D view of solar activity. We just happen to be passing through the L4 and L5 Lagrange points en route. This is purely bonus science."
Scientists think Theia may even have formed in one of these gravitational points of balance from the accumulation of flotsam that had built up there.
"Computer models show that Theia could have grown large enough to produce the moon if it formed in the L4 or L5 [Lagrangian] regions, where the balance of forces allowed enough material to accumulate," Kaiser said. "Later, Theia would have been nudged out of L4 or L5 by the increasing gravity of other developing planets like Venus and sent on a collision course with Earth."
- 24 Hours of Chaos: The Day The Moon Was Made
- Multimedia: How Lagrange Points Work
- Top 10 Cool Moon Facts
Torn Away: The Moon's Violent Birth Earth Hit by Neighbor in Making of Moon
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Labels: lost planet - birth of moon
Top Ten Extrasolar Planets
Number 10: The First
Worlds Collide- video
Two Worlds Collide in Deep Space
Two distant planets orbiting a young star apparently smashed into each other at high speeds thousands of years ago in a cosmic pileup of cataclysmic proportions, astronomers announced Monday.
Telltale plumes of vaporized rock and lava leftover from the collision revealed its existence to NASA's Spitzer Space Telescope, which picked up signatures from the impact in recent observations.
The two-planet pileup occurred within the last few thousand years or so - a relatively recent cosmic timeframe. The smaller of the two bodies - a planet about the size of Earth's moon, according to computer models - was apparently destroyed by the crash. The other was most likely a Mercury-sized-planet and survived, albeit severely dented.
"This collision had to be huge and incredibly high-speed for rock to have been vaporized and melted," said Carey Lisse of the Johns Hopkins University Applied Physics Laboratory in Maryland, lead author of a paper describing the findings in the Aug. 20 issue of the Astrophysical Journal.
Researchers believe the planets were moving at about 22,400 mph (10 kilometers per second) before the crash. The violent wreck released amorphous silica rock, or melted glass, and hardened chunks of lava called tektites. Spitzer also spotted large clouds of orbiting silicon monoxide gas created when the rock was vaporized.
"This is a really rare and short-lived event, critical in the formation of Earth-like planets and moons," Lisse said. "We're lucky to have witnessed one not long after it happened."
Infrared detectors on Spitzer found the traces of rocky rubble and re-frozen lava around a young star, called HD 172555, still in the early stages of planet formation. The system is about 100 light-years from Earth. One light-year is the distance light travels in a year six trillion miles (9.7 trillion km).
A similar fender-bender is thought to have formed Earth's moon more than 4 billion years ago, when a body the size of Mars rammed into Earth.
"The collision that formed our moon would have been tremendous, enough to melt the surface of Earth," said co-author Geoff Bryden of NASA's Jet Propulsion Laboratory in California. "Debris from the collision most likely settled into a disk around Earth that eventually coalesced to make the moon. This is about the same scale of impact we're seeing with Spitzer - we don't know if a moon will form or not, but we know a large rocky body's surface was red hot, warped and melted."
In fact, such violent encounters seem to have been common in our own solar system's early history. For example, giant impacts are thought to have stripped Mercury of its outer crust, tipped Uranus on its side, and spun Venus backward.
As recently as last month, a small space rock slammed into Jupiter, making a large black bruise.
In general, rocky planets like Earth coalesce and grow when small rocks crash and clump together, merging their cores.
The system around HD 172555 is a relative baby at only 12 million years old, compared to our solar system's age of 4.5 billion years.
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