Yikes! The trailer for an upcoming film “Gravity” is absolutely terrifying. This movie won’t hit theaters until October 4, 2013, so we can expect to see more trailers after this first ‘teaser.” We do know it is directed by Alfonso Cuarón and stars Sandra Bullock and George Clooney. But with an emergency spacewalk likely taking place tomorrow at the International Space Station, the timing of the release of this trailer is just a bit eerie.
Bullock plays a medical engineer on her first shuttle mission, with veteran astronaut Matt Kowalsky (Clooney) in command of his last flight before retiring. But on a seemingly routine spacewalk, disaster strikes. The shuttle is destroyed, the space station is damaged, leaving the two astronauts completely alone and tethered to nothing but each other and spiraling out into the blackness.
Watch the teaser below:
The word on the street is that NASA was not consulted at all for this film, so we can only hope for a hint of reality (i.e., let hope it’s not another “Armageddon.”) But from the trailer, it seems to follow the recipe for any space disaster film: go into space, have the mission go awry, bring in the heroes to save the day. Guesses on thumbs up or down?
A unique and exotic laboratory about 6,800 light-years from Earth is helping Earth-based astronomers test Albert Einstein’s theory of general relativity in ways not possible until now. And the observations exactly match predictions from general relativity, say scientists in a paper to be published in the April 26 issue of the journal Science.
Using ESO’s Very Large Telescope along with other radio telescopes, John Antoniadis, a PhD student at the Max Planck Institute for radio Astronomy (MPIfR) in Bonn and lead author of the paper, says the bizarre pair of stars makes for an excellent test case for physics.
“I was observing the system with ESO’s Very Large Telescope, looking for changes in the light emitted from the white dwarf caused by its motion around the pulsar,” says Antoniadis. “A quick on-the-spot analysis made me realize that the pulsar was quite a heavyweight. It is twice the mass of the Sun, making it the most massive neutron star that we know of and also an excellent laboratory for fundamental physics.”
The strange pair consists of a tiny and unusually heavy neutron star that spins 25 times per second. The pulsar, named PSR J0348+0432 is the remains of a supernova explosion. Twice as heavy as our Sun, the pulsar would fit within the confines of the Denver metropolitan area; it’s just 20 kilometers across or about 12 miles. The gravity on this strange star is more than 300 billion times stronger than on Earth. At its center, where the intense gravity squeezes matter even more tightly together, a sugar-cubed-sized block of star stuff would weight more than one billion tons. Only three other pulsars outside globular clusters spin faster and have shorter periods.
In addition, a much larger white dwarf, the extremely hot, burned-out core of a Sun-like star, whips around J0348+0432 every 2.5 hours.
As a consequence, radio astronomers Ryan Lynch and colleagues who discovered the pulsar in 2011, realized the pair would enable scientists to test theories of gravity that were not possible before. Einstein’s general theory of relativity describes gravity as a curvature in spacetime. Like a bowling ball nestled in a stretched bedsheet, spacetime bends and warps in the presence of mass and energy. The theory, published in 1916, has withstood all tests so far as the simplest explanation for observed astronomical phenomena. Other theories of gravity make different predictions but these differences would reveal themselves only in extremely strong gravitational fields not found within our solar system. J0348+0432 offered the opportunity to study Einstein’s theory in detail.
This video shows an artist’s impression of the exotic double object known as PSR J0348+0432. This system is radiating gravitational radiation, or ripples, in spacetime. Although these waves cannot be yet detected directly by astronomers on Earth they can be detected indirectly by measuring the change in the orbit of the system as it loses energy. Credit: ESO/L.Calçada
Antoniadis’ team combined observations of the white dwarf from the European Southern Observatory’s Very Large Telescope with the precise timing of the pulsar from other radio telescopes, including the Green Bank Telescope in West Virginia, Effelsberg 100 meter radio telescope in Germany, and the Arecibo Observatory in Puerto Rico. Astronomers predict such close pulsar binaries radiate gravity waves and lose minute amounts of energy over time causing the orbital period of the white dwarf companion to change slightly. The astronomers found that predictions for this change closely matched those of general relativity while competing theories were different.
“Our radio observations were so precise that we have already been able to measure a change in the orbital period of 8 millionths of a second per year, exactly what Einstein’s theory predicts,” states Paulo Freire, another team member, in the press release.
Color composite of Titan and Dione made from Cassini images acquired in May 2011. (NASA/JPL/SSI/J. Major)
It’s long been speculated that Saturn’s moon Titan may be harboring a global subsurface ocean below an icy crust, based on measurements of its rotation and orbit by NASA’s Cassini spacecraft. Titan exhibits a density and shape that indicates a pliable liquid internal layer — an underground ocean — possibly composed of water mixed with ammonia, a combination that would help explain the consistent amount of methane found in its thick atmosphere.
Now, further analysis of Cassini gravity measurements by a Stanford University team has shown that Titan’s ice layer is thicker and less uniform than originally estimated, indicating a more complex internal structure — and a stronger external influences for its heat.
Titan’s liquid subsurface ocean was previously estimated to be in the neighborhood of 100 km (62 miles) thick, sandwiched between a rocky core below and an icy shell above. This was based on the behavior of Titan in its orbit — or, more precisely, how Titan’s shape changes along the course of its orbit, as measured by Cassini’s radar instrument.
Because Titan’s 16-day orbit is not perfectly circular the moon experiences a stronger gravitational pull from Saturn at certain points than at others. As a result it’s flattened at the poles and constantly changing shape slightly — an effect called tidal flexing. Along with the decay of radioactive materials in its core, this flexing generates the internal heat that helps keep a subsurface ocean liquid.
A team of researchers from Stanford University, led by Howard Zebker, professor of geophysics and electrical engineering, used recent Cassini measurements of Titan’s topography and gravity to determine that the icy layer between the moon’s surface and ocean is up to twice as thick as previously thought — and it’s considerably thicker at the equator than at the poles.
“The picture of Titan that we get has an icy, rocky core with a radius of a little over 2,000 kilometers, an ocean somewhere in the range of 225 to 300 kilometers thick and an ice layer that is 200 kilometers thick,” said Zebker.
Different thicknesses of Titan’s ice layer would mean that there’s less heat being generated internally by the decay of radioactive materials in Titan’s core, because that type of heat would be more or less globally uniform. Instead, tidal flexing caused by the gravitational interactions with Saturn and neighboring smaller moons must play a stronger role in heating Titan’s insides.
With Cassini’s new measurements of Titan’s gravity, Zebker and his team calculated that the icy layer below Titan’s flattened poles is 3,000 meters (about 1.8 miles) thinner than average, while at the equator it’s 3,000 meters thicker than average. Combined with the moon’s surface features, this makes the average global thickness of the ice layer to be more like 200 km, not 100.
Heat generated by tidal flexing — which is more strongly felt at the poles — is thought to be the cause of the thinner ice there. Thinner ice would mean there’s more liquid water beneath the poles, which is denser and thus would exert a stronger gravitational pull… exactly what’s been found in Cassini’s measurements.
Two white dwarfs similar to those in the system SDSS J065133.338+284423.37 spiral together in this illustration from NASA. Credit: D. Berry/NASA GSFC
Locked in a spiraling orbital embrace, the super-dense remains of two dead stars are giving astronomers the evidence needed to confirm one of Einstein’s predictions about the Universe.
A binary system located about 3,000 light-years away, SDSS J065133.338+284423.37 (J0651 for short) contains two white dwarfs orbiting each other rapidly — once every 12.75 minutes. The system was discovered in April 2011, and since then astronomers have had their eyes — and four separate telescopes in locations around the world — on it to see if gravitational effects first predicted by Einstein could be seen.
According to Einstein, space-time is a structure in itself, in which all cosmic objects — planets, stars, galaxies — reside. Every object with mass puts a “dent” in this structure in all dimensions; the more massive an object, the “deeper” the dent. Light energy travels in a straight line, but when it encounters these dents it can dip in and veer off-course, an effect we see from Earth as gravitational lensing.
Einstein also predicted that exceptionally massive, rapidly rotating objects — such as a white dwarf binary pair — would create outwardly-expanding ripples in space-time that would ultimately “steal” kinetic energy from the objects themselves. These gravitational waves would be very subtle, yet in theory, observable.
What researchers led by a team at The University of Texas at Austin have found is optical evidence of gravitational waves slowing down the stars in J0651. Originally observed in 2011 eclipsing each other (as seen from Earth) once every six minutes, the stars now eclipse six seconds sooner. This equates to a predicted orbital period reduction of about 0.25 milliseconds each year.*
“These compact stars are orbiting each other so closely that we have been able to observe the usually negligible influence of gravitational waves using a relatively simple camera on a 75-year-old telescope in just 13 months,” said study lead author J.J. Hermes, a graduate student at The University of Texas at Austin.
Based on these measurements, by April 2013 the stars will be eclipsing each other 20 seconds sooner than first observed. Eventually they will merge together entirely.
Although this isn’t “direct” observation of gravitational waves, it is evidence inferred by their predicted effects… akin to watching a floating lantern in a dark pond at night moving up and down and deducing that there are waves present.
“It’s exciting to confirm predictions Einstein made nearly a century ago by watching two stars bobbing in the wake caused by their sheer mass,” said Hermes.
As of early last year NASA and ESA had a proposed mission called LISA (Laser Interferometer Space Antenna) that would have put a series of 3 detectors into space 5 million km apart, connected by lasers. This arrangement of precision-positioned spacecraft could have detected any passing gravitational waves in the local space-time neighborhood, making direct observation possible. Sadly this mission was canceled due to FY2012 budget cuts for NASA, but ESA is moving ahead with developments for its own gravitational wave mission, called eLISA/NGO — the first “pathfinder” portion of which is slated to launch in 2014.
The study was submitted to Astrophysical Journal Letters on August 24. Read more on the McDonald Observatory news release here.
Inset image: simulation of binary black holes causing gravitational waves – C. Reisswig, L. Rezzolla (AEI); Scientific visualization – M. Koppitz (AEI & Zuse Institute Berlin)
*The difference in the eclipse time is noted as six seconds even though the orbital period decay of the two stars is only .25 milliseconds/year because of a pile-up effect of all the eclipses observed since April 2011. The measurements made by the research team takes into consideration the phase change in the J0651 system, which experiences a piling effect — similar to an out-of-sync watch — that increases relative to time^2 and is therefore a larger and easier number to detect and work with. Once that was measured, the actual orbital period decay could be figured out.
As part of his ongoing (and always entertaining) “Science Off the Sphere” series, Expedition 31 flight engineer Don Pettit experiments in orbit with a classic bit of summertime fun: water balloons.
Captured in real-time and slow-motion, we get to see how water behaves when suddenly freed from the restraints of an inflated latex balloon… and gravity. With Don NASA doesn’t only get a flight engineer, it gets its very own Mr. Wizard in space — check it out!
Until relatively recently, Mercury was one of the most poorly understood planets in the inner solar system. The MESSENGER mission to Mercury, is changing all of the that. New results from the Mercury Laser Altimeter (MLA) and gravity measurements are showing us that the planet closest to our sun is thin skinned and wrinkled, which is very different from what we originally thought.
The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft was launched back in 2004. It took a long time getting to its destination, completing 3 flybys of Mercury before finally entering orbit a little over a year ago. Currently, the spacecraft is in a highly eccentric polar orbit, approaching the planet much closer in the north than in the south. This allows the northern hemisphere to be probed and imaged at enviably high resolutions, but leaves the southern hemisphere poorly understood.
Even so, the data returned from MESSENGER is showing us some quite unanticipated findings. Two papers from the MESSENGER team, published in today’s issue of Science, are showing some surprising results from the laser altimeter and gravity experiments.
Using NASA’s Deep Space Network, Earth-based radio tracking of MESSENGER has allowed minute changes in the spacecraft’s orbit to be monitored and recorded. From this, Dr. Maria Zuber of MIT and her team calculated a model of Mercury’s gravity. Meanwhile, the on-board laser altimeter has provided invaluable topographic information. Combined together, these data have allowed the MESSENGER team to glean a great deal of information about the planet’s interior workings.
One of the most striking findings is that the iron-rich core of Mercury is very large. A combination of measurements and models suggest that the core has both a solid interior portion and a liquid outer portion. And while it is not certain how much of the core is solid and how much is liquid, it is clear that the total core has a radius of about 2030 km. This is a huge core, representing 83% of Mercury’s 2440 km radius!
Furthermore, these calculations suggest that the layer above the core is much denser than previously expected. Results from MESSENGER’s X-Ray spectrometer indicate that the crust, and by extension the mantle, are too low in iron to explain this high density. Dr. Zuber’s team think that the only way to explain this discrepancy is by the presence of a solid iron-sulfur layer just above the core. Such a layer could be anywhere from 20 to 200 km thick, leaving only a very thin crust and mantle at the top. This kind of interior structure is completely different from what was originally suggested for Mercury, and it is nothing like what we have seen in the other planets!
This striking fact may help explain some unexpected altimeter results, which show that Mercury’s topography has less variation than other planets. The total difference between the highest and lowest elevations on Mercury is only 9.85 km. Meanwhile, the Moon has a total difference of 19.9 km between its highest and lowest points, and on Mars this difference is 30 km. Dr. Zuber and her team speculate that the presence of the core so close to the surface could keep the mantle hot, allowing topographic features to relax. In such a scenario, the lithosphere under tall impact-formed mountains would sink down into a mushy mantle that cannot support their weight. Conversely, the thin lithosphere under impact basins would rebound upwards, taking part of the mobile mantle with it.
In fact, the gravity data shows evidence of exactly this kind of process, in the form of “mascons”. These mass concentrations form when large imacts make the local crust very thin, allowing denser mantle material to rise closer to the surface as the lithosphere rebounds from the impact event. Mascons are well known from studies on the Moon and Mars, and now MESSENGER’s gravity data has revealed three such mascons on Mercury, located in the Caloris, Sobkou, and Budh basins.
Interestingly enough, the mascons in Sobkou and Budh basins are not immediately obvious. They only show up when the effects of a regional topographic high are adjusted for. This topographic feature is a large quasi-linear rise that extends over half the circumference of Mercury in the mid-latitudes. The rise even passes through the northern part Caloris basin (which is large enough that its mascon is not overwhelmed by the rise). Studies of this rise by the MESSENGER team suggest that it is relatively young, having formed well after the formation of the basins, after the volcanic flooding of their interiors and exteriors, and even after some of the later impact craters that cover the flooded surfaces.
Dr. Zuber and her team also identified another young topographically elevated region, the Northern Rise, located in the lowlands surrounding the North Pole. They speculate that these young rises represent a buckling of the lithosphere, which happened when the planet’s interior cooled and contracted. This interpretation is supported by the presence of lobate scarps and ridges that can be seen around the planet, and which represent faulting of the crust when it was compressed.
So, it seems that Mercury is unlike the other planets of the Solar System. It appears to have a disproportionately large core that is covered by a thin skin of mantle and lithosphere. Furthermore, this skin seems to have wrinkled like a raisin’s when the huge core of the planet shrunk as it cooled.
Gravity Field and Internal Structure of Mercury from MESSENGER, Smith et al., Science V336 (6078), 214-217, April 13 2012, DOI:10.1126/science.1218809
Topography of the Northern Hemisphere of Mercury from MESSENGER Laser Altimetry, Zuber et al., Science V336 (6078), 217-220, April 13 2012, DOI:10.1126/science.1218805
Expedition 30 astronaut and chemical engineer Don Pettit continues his ongoing “Science off the Sphere” series with this latest installment, in which he demonstrates some of the peculiar behaviors of thin sheets of water in microgravity. Check it out — you might be surprised how water behaves when freed from the bounds of gravity (and put under the command of a cosmic chemist!)
A classroom of America’s Youth from an elementary school in Bozeman, Montana submitted the stellar winning entry in NASA’s nationwide student essay contest to rename the twin GRAIL lunar probes that just achieved orbit around our Moon on New Year’s Eve and New Year’s Day 2012
“Ebb” & “Flow” – are the dynamic duo’s official new names and were selected because they clearly illuminate the science goals of the gravity mapping spacecraft and how the Moon’s influence mightily affects Earth every day in a manner that’s easy for everyone to understand.
“The 28 students of Nina DiMauro’s class at the Emily Dickinson Elementary School have really hit the nail on the head,” said GRAIL principal investigator Prof. Maria Zuber of the Massachusetts Institute of Technology in Cambridge, Mass.
“We asked the youth of America to assist us in getting better names.”
“We chose Ebb and Flow because it’s the daily example of how the Moon’s gravity is working on the Earth,” said Zuber during a media briefing held today (Jan. 17) at NASA Headquarters in Washington, D.C. The terms ebb and flow refer to the movement of the tides on Earth due to the gravitational pull from the Moon.
“We were really impressed that the students drew their inspiration by researching GRAIL and its goal of measuring gravity. Ebb and Flow truly capture the spirit and excitement of our mission.”
Ebb and Flow are flying in tandem around Earth’s only natural satellite, the first time such a feat has ever been attempted.
As they fly over mountains, craters and basins on the Moon, the spaceships will move back and forth in orbit in an “ebb and flow” like response to the changing lunar gravity field and transmit radio signals to precisely measure the variations to within 1 micron, the width of a red blood cell.
The breakthrough science expected from the mirror image twins will provide unprecedented insight into what lurks mysteriously hidden beneath the surface of our nearest neighbor and deep into the interior.
The winning names from the 4th Graders of Emily Dickinson Elementary School were chosen from essays submitted by nearly 900 classrooms across America with over 11,000 students from 45 states, Puerto Rico and the District of Columbia, Zuber explained.
The students themselves announced “Ebb” and “Flow” in a dramaric live broadcast televised on NASA TV via Skype.
“We are so thrilled that our names were chosen and excited to share this with you. We can’t believe we won! We are so honored. Thank you!” said Ms. DiMauro as the very enthusiastic students spelled out the names by holding up the individual letters one-by-one on big placards from their classroom desks in Montana.
Watch the 4th Grade Kids spell the names in this video!
Until now the pair of probes went by the rather uninspiring monikers of GRAIL “A” and “B”. GRAIL stands for Gravity Recovery And Interior Laboratory.
The twin crafts’ new names were selected jointly by Prof. Zuber and Dr. Sally Ride, America’s first woman astronaut, and announced during today’s NASA briefing.
NASA’s naming competition was open to K-12 students who submitted pairs of names and a short essay to justified their suggestions.
“Ebb” and “Flow” (GRAIL A and GRAIL B) are the size of washing machines and were launched side by side atop a Delta II booster rocket on September 10, 2011 from Cape Canaveral, Florida.
They followed a circuitous 3.5 month low energy path to the Moon to minimize the fuel requirements and overall costs.
So far the probes have completed three burns of their main engines aimed at lowering and circularizing their initial highly elliptical orbits. The orbital period has also been reduced from 11.5 hours to just under 4 hours as of today.
“The science phase begins in early March,” said Zuber. At that time the twins will be flying in tandem at 55 kilometers (34 miles) altitude.
The GRAIL twins are also equipped with a very special camera dubbed MoonKAM (Moon Knowledge Acquired by Middle school students) whose purpose is to inspire kids to study science.
“GRAIL is NASA’s first planetary spacecraft mission carrying instruments entirely dedicated to education and public outreach,” explained Sally Ride. “Over 2100 classrooms have signed up so far to participate.”
Thousands of middle school students in grades five through eight will select target areas on the lunar surface and send requests for study to the GRAIL MoonKAM Mission Operations Center in San Diego which is managed by Dr. Ride in collaboration with undergraduate students at the University of California in San Diego.
By having their names selected, the 4th graders from Emily Dickinson Elementary have also won the prize to choose the first target on the Moon to photograph with the MoonKam cameras, said Ride.
Zuber notes that the first MoonKAM images will be snapped shortly after the 82 day science phase begins on March 8.
Yep. It’s that time of year again. Time to enjoy the Andromeda Galaxy at almost every observing opportunity. But now, rather than just look at the nearest spiral to the Milky Way and sneaking a peak at satellites M32 and M110, we can think about something more when we peer M31’s way. There are two newly discovered dwarf galaxies that appear to be companions of Andromeda!
Eric Bell, an associate professor in astronomy, and Colin Slater, an astronomy Ph.D. student, found Andromeda 28 and Andromeda 29 by utilizing the Sloan Digital Sky Survey and a recently developed star counting technique. To back up their observations, the team employed data from the Gemini North Telescope in Hawaii. Located at 1.1 million and 600,000 light-years respectively, Andromeda XXVIII and Andromeda XXIX have the distinction of being the two furthest satellite galaxies ever detected away from the host – M31. Can they be spotted with amateur equipment? Not hardly. This pair comes in about 100,000 fainter than Andromeda itself and can barely be discerned with some of the world’s largest telescopes. They’re so faint, they haven’t even been classified yet.
“With presently available imaging we are unable to determine whether there is ongoing or recent star formation, which prevents us from classifying it as a dwarf spheroidal or a dwarf irregular.” explains Bell.
In their work – published in a recent edition of the edition of the Astrophysical Journal Letters – the team of Bell and Slater explains how they were searching for dwarf galaxies around Andromeda to help them understand how physical matter relates to theoretical dark matter. While we can’t see it, hear it, touch it or smell it, we know it’s there because of its gravitational influence. And when it comes to gravity, many astronomers are convinced that dark matter plays a role in organizing galaxy structure.
“These faint, dwarf, relatively nearby galaxies are a real battleground in trying to understand how dark matter acts at small scales,” Bell said. “The stakes are high.”
Right now, current consensus has all galaxies embedded in surrounding dark matter… and each “bed” of dark matter should have a galaxy. Considering the volume of the Universe, these predictions are pretty much spot on – if we take only large galaxies into account.
“But it seems to break down when we get to smaller galaxies,” Slater said. “The models predict far more dark matter halos than we observe galaxies. We don’t know if it’s because we’re not seeing all of the galaxies or because our predictions are wrong.”
“The exciting answer,” Bell said, “would be that there just aren’t that many dark matter halos.” Bell said. “This is part of the grand effort to test that paradigm.”
Right or wrong… pondering dark matter and dwarf galaxies while observing Andromeda will add a whole new dimension to your observations!
For Further Reading: Andromeda XXVIII: A Dwarf Galaxy more than 350 kpc from Andromeda and Andromeda XXIX: A New Dwarf Spheroidal Galaxy 200 kpc from Andromeda.
Sir Issac Newton is best know for his laws of motion. Many people’s knowledge of his scientific contributions stops there. Issac Newtons inventions contributed a great deal to our current understanding of subjects from optics to theology and how early scientists were able to view their world.
In mathematics Isaac Newton inventions included laying the ground work for differential and integral calculus. His work was based on his insight that the integration of a function is merely the inverse procedure to differentiating it. Taking differentiation as the basic operation, he produced simple analytical methods that unified many separate techniques previously developed to solve apparently unrelated problems such as finding areas, tangents, the lengths of curves and the maxima and minima of functions.
Issac Newton inventions in mechanics and gravitation were summarized the Principia. His discoveries in terrestrial and celestial mechanics showed how universal gravitation provided an explanation of falling bodies on Earth and of the motions of planets, comets, and other bodies in the heavens. He explained a wide range of then unrelated phenomena: the eccentric orbits of comets, the tides and their variations, the precession of the Earth’s axis, and motion of the Moon as perturbed by the gravity of the Sun. This work includes Newton’s three famous laws of motion, fluid motion, and an explanation of Kepler’s laws of planetary motion.
Isaac Newton inventions in optics included his observation that white light could be separated by a prism into a spectrum of different colors, each characterized by a unique refractivity. He proposed the corpuscular theory of light. He was the first person to understand the rainbow. He was the first person to use a curved mirror in a telescope to prevent light form being broken up into unwanted colors.
Isaac Newton inventions and contributions to science were many and varied. They covered revolutionary ideas and practical inventions. His works in physics, mathematics and astronomy are still important today. His contributions in any one of these fields would have made him famous; taken as a whole, they make him truly outstanding.
We have written many articles about Isaac Newton’s inventions for Universe Today. Here’s an article about celestial mechanics, and here’s an article about Newton’s laws of motion.