December 13, 2007, 8:56 PM CT

Europa: A Closer Look Is Possible

Jupiter's moon Europa is just as far away as ever, but new research is bringing researchers closer to being able to explore its tantalizing ice-covered ocean and determine its potential for harboring life.

"We've learned a lot about Europa in the past few years," says William McKinnon, professor of Earth and Planetary Sciences at Washington University in St. Louis, Mo.

"Before we were almost sure that there was an ocean, but now the scientific community has come to a consensus that there most certainly is an ocean. We're ready to take the next step and explore that ocean and the ice shell that overlays it. We have many new discoveries and techniques that can help us do that".

McKinnon is discussing some of these recent findings and new opportunities for exploring Europa in a news briefing today at the meeting of the American Geophysical Union in San Francisco. He is joined by colleagues Donald Blankenship, research scientist at the Institute for Geophysics at the University of Texas at Austin's Jackson School of Geosciences., and Peter Doran, associate professor of Earth and Environmental Sciences, University of Illinois at Chicago.

McKinnon points to refined methods that can use combined measurements of gravity and the magnetic field made from orbit to characterize Europa's ocean. By observing how the moon flexes and deforms and by measuring magnetic variations, scientists can determine how thick or thin the ice is over the ocean and even learn how salty the ocean is. A new model shows that radiation on Europa is much less, up to two-thirds less, than prior models predicted, making the environment much more hospitable for orbiting spacecraft or landers to operate......... Posted by: Sean      Read more         Source

December 11, 2007, 10:36 PM CT

Hazy red sunset on extrasolar planet

A team of astronomers have used the NASA/ESA Hubble Space Telescope to detect, for the first time, good evidence of hazes in the atmosphere of a planet orbiting a distant star. The discovery comes after extensive observations made recently with Hubbles Advanced Camera for Surveys (ACS).

The team, led by Frdric Pont from the Geneva University Observatory in Switzerland, used Hubbles ACS to make the first detection of hazes in the atmosphere of the giant planet. "One of the long-term goals of studying extrasolar planets is to measure the atmosphere of an Earth-like planet, this present result is a step in this direction" says Pont. "HD 189733b is the first extrasolar planet for which we are piecing together a complete idea of what it really looks like".

The new observations were made as the extrasolar planet, dubbed HD 189733b, passed in front of its parent star in a transit. As the light from the star passes through the atmosphere around the limb of the giant extrasolar planet, the gases in the atmosphere stamp their unique signature on the starlight from HD 189733.

The planet itself, orbiting close to its parent star, is a hot-Jupiter type of gas giant slightly larger than Jupiter. The proximity to its star results in an atmospheric temperature of roughly seven hundred degrees Celsius. Measurements of the way light varies as the planet passes in front of its parent star indicates that HD 189733b has neither Earth-sized moons nor any discernable Saturn-like ring system......... Posted by: Sean      Read more         Source

December 11, 2007, 10:07 PM CT

New discoveries about Northern Lights

A fleet of NASA spacecraft, launched less than eight months ago, has made three important discoveries about spectacular eruptions of Northern Lights called "substorms" and the source of their power.

NASA's Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission observed the dynamics of a rapidly developing substorm, confirmed the existence of giant magnetic ropes and witnessed small explosions in the outskirts of Earth's magnetic field. The findings will be presented at the annual meeting of the American Geophysical Union in San Francisco in December.

The discoveries began on March 23, when a substorm erupted over Alaska and Canada, producing vivid auroras for more than two hours. A network of ground cameras organized to support THEMIS photographed the display from below while the satellites measured particles and fields from above.

“The substorm behaved quite unexpectedly," says Vassilis Angelopoulos, the mission's principal investigator at the University of California, Los Angeles. "The auroras surged westward twice as fast as anyone thought possible, crossing 15 degrees of longitude in less than one minute. The storm traversed an entire polar time zone, or 400 miles, in 60 seconds flat.”

Photographs taken by ground cameras and NASA's Polar satellite (also supporting the THEMIS mission) revealed a series of staccato outbursts each lasting about 10 minutes. Angelopoulos said that some of the bursts died out while others reinforced each other and went on to become major onsets......... Posted by: Sean      Read more         Source

December 11, 2007, 8:23 PM CT

Just flip-flop the position of Uranus and Neptune

Quick: Whats the order of the planets in the solar system? Need a little help? Maybe the following mnemonic rings a bell: My Very Educated Mother Just Served Up Nine Pizzas. Its useful for remembering the order of the planets today, but it wouldnt have been as useful in the past, and not just because the International Astronomical Union demoted Pluto to dwarf planet last year. The reason this mnemonic wouldnt have worked is because the planets werent always in the order they are today. Four billion years ago, early in the solar systems evolution, Uranus and Neptune switched places.

This is the result of recent work by Steve Desch, assistant professor in the School of Earth and Space Exploration at Arizona State University. The work appears in this weeks Astrophysical Journal. Desch based his conclusion on his calculations of the surface density of the solar nebula. The solar nebula is the disk of gas and dust out of which all of the planets formed. The surface density or mass per area of the solar nebula protoplanetary disk is a fundamental quantity needed to calculate everything from how fast planets grow to the types of chemicals they are likely to contain.

Its very hard to observe the surface density in protoplanetary disks forming solar systems today, both because theyre too far away and because most observations detect only dust and miss everything larger than a baseball. So for the last 30 years most scientists have relied on an estimate of the surface density called the Minimum Mass Solar Nebula. The idea is simple: take the rocky component of each planet, add hydrogen and helium until it matches the Sun in composition, and spread the mass over the area of each planets orbit. The minimum mass solar nebula predicts disk masses not too different from what we can observe in forming solar systems. But it also predicts low surface densities, with the mass too spread out to form planets quickly......... Posted by: Sean      Read more         Source

December 10, 2007, 10:54 PM CT

The Solar System Is Squashed

NASA's Voyager 2 spacecraft has followed its twin Voyager 1 into the solar system's final frontier, a vast region at the edge of our solar system where the solar wind runs up against the thin gas between the stars.

However, Voyager 2 took a different path, entering this region, called the heliosheath, on August 30, 2007. Because Voyager 2 crossed the heliosheath boundary, called the solar wind termination shock, about 10 billion miles away from Voyager 1 and almost a billion miles closer to the sun, it confirmed that our solar system is "squashed" or "dented"- that the bubble carved into interstellar space by the solar wind is not perfectly round. Where Voyager 2 made its crossing, the bubble is pushed in closer to the sun by the local interstellar magnetic field.

"Voyager 2 continues its journey of discovery, crossing the termination shock multiple times as it entered the outermost layer of the giant heliospheric bubble surrounding the Sun and joined Voyager 1 in the last leg of the race to interstellar space." said Voyager Project Scientist Dr. Edward Stone of the California Institute of Technology, Pasadena, Calif.

The solar wind is a thin gas of electrically charged particles (plasma) blown into space by the sun. The solar wind blows in all directions, carving a bubble into interstellar space that extends past the orbit of Pluto. This bubble is called the heliosphere, and Voyager 1 was the first spacecraft to explore its outer layer, when it crossed into the heliosheath in December 2004. As Voyager 1 made this historic passage, it encountered the shock wave that surrounds our solar system called the solar wind termination shock, where the solar wind is abruptly slowed by pressure from the gas and magnetic field in interstellar space......... Posted by: Sean      Read more         Source

December 10, 2007, 10:34 PM CT

Surprises At Solar System's Edge

The Voyager 2 spacecraft's Plasma Science instrument, developed at MIT in the 1970s, has turned up surprising revelations about the boundary zone that marks the edge of the sun's influence in space.

The unexpected findings emerged in the last few weeks as the spacecraft traversed the termination shockwave formed when the flow of particles constantly streaming out from the sun--the solar wind--slams into the surrounding thin gas that fills the space between stars.

The first surprise is that there is an unexpectedly strong magnetic field in that surrounding interstellar region, generated by currents in that incredibly tenuous gas. This magnetic field is squashing the bubble of outflowing gas from the sun, distorting it from the uniform spherical shape space physicists had expected to find.

A second surprise also emerged from Voyager 2's passage through the solar system's outer edge: Just outside that boundary the temperature, eventhough hotter than inside, was ten times cooler than expected. Theorists had to scramble to come up with an explanation for the unanticipated chilling effect.

"It's a different kind of shockwave than we've seen anywhere else," says John Richardson, principal investigator for the Plasma Physics instrument and a Principal Research Scientist at MIT's Kavli Institute for Astrophysics and Space Science. The unexpected coolness, theorists now think, is caused by energy going into particles that are hotter than those that can be measured by the MIT plasma instrument......... Posted by: Sean      Read more         Source

December 6, 2007, 8:03 PM CT

Testing time for instrument on Hubble's successor

A significant milestone for the Hubble Space Telescope successor, the James Webb Space Telescope (JWST), is on course to be reached before Christmas with the testing of the verification model of the Mid-InfraRed Instrument (MIRI) at the Rutherford Appleton Laboratory in Oxfordshire.

MIRI is one of four sophisticated instruments onboard which will study the early universe and properties of materials forming around new born stars in unprecedented detail. It will also be able to image directly massive planets orbiting other stars.

At the heart of the JWST observatory is a large cold telescope whose primary mirror measures 6.5 metres in diameter in comparison to 2.4 metres for Hubble, providing an enormous increase in capability to investigate the origin and evolution of galaxies, stars and planetary systems. Due for launch in 2013, JWST, which is a joint cooperative mission between NASA, the European Space Agency (ESA) and the Canadian Space Agency (CSA), is optimised to operate over a wide range of infrared wavelengths.

MIRI is the first of the JWST instruments to reach this phase of cryogenic performance testing and marks a significant milestone for this international team, which is funded in the UK by the Science and Technology Facilities Council [STFC] and spread across STFCs UK Astronomy Technology Centre (UK ATC) and Rutherford Appleton Laboratory [RAL], plus team members at Astrium Ltd, and the universities of Leicester and Cardiff......... Posted by: Sean      Read more         Source

December 6, 2007, 3:43 PM CT

Searching for the missing matter

Much of the gaseous mass of the universe is bound up in a tangled web of cosmic filaments that stretch for hundreds of millions of light-years, as per a new supercomputer study by a team led by the University of Colorado at Boulder.

The study indicated a significant portion of the gas is in the filaments -- which connect galaxy clusters -- hidden from direct observation in enormous gas clouds in intergalactic space known as the Warm-Hot Intergalactic Medium, or WHIM, said CU-Boulder Professor Jack Burns of the astrophysical and planetary sciences department. The team performed one of the largest cosmological supercomputer simulations ever, cramming 2.5 percent of the visible universe inside a computer to model a region more than 1.5 billion light-years across. One light-year is equal to about six trillion miles.

A paper on the subject would be reported in the Dec. 10 issue of the Astrophysical Journal. In addition to Burns, the paper was authored by CU-Boulder Research Associate Eric Hallman of APS, Brian O'Shea of Los Alamos National Laboratory, Michael Norman and Rick Wagner of the University of California, San Diego and Robert Harkness of the San Diego Supercomputing Center.

It took the scientists nearly a decade to produce the extraordinarily complex computer code that drove the simulation, which incorporated virtually all of the known physical conditions of the universe reaching back in time almost to the Big Bang, said Burns. The simulation -- which uses advanced numerical techniques to zoom-in on interesting structures in the universe -- modeled the motion of matter as it collapsed due to gravity and became dense enough to form cosmic filaments and galaxy structures......... Posted by: Sean      Read more         Source

December 4, 2007, 10:35 PM CT

How white dwarf stars get their 'kicks'

University of British Columbia astronomer Harvey Richer and UBC graduate student Saul Davis have discovered that white dwarf stars are born with a natal kick, explaining why these smoldering embers of Sun-like stars are found on the edge rather than at the centre of globular star clusters.

White dwarfs represent the third major stage of a stars evolution. Like the Sun, each star begins its life with a long stable state where nuclear reactions take place in the core supplying the energy. After the core fuel is depleted, it swells up and turns into a huge red giant. Later, the red giant ejects its outer atmosphere and its core becomes a white dwarf that slowly cools over time and radiates its stored thermal heat into space.

Using NASAs Hubble telescope, Richer and his team looked at the position of white dwarfs in NGC 6397, one of the globular star clusters closest to Earth. Globular clusters are dense swarms of hundreds of thousands of stars. About 150 of these clusters exist in the Milky Way, each containing between 100,000 and one million stars.

The distribution of young white dwarfs is the exact opposite of what we expected, says Prof. Richer, whose study will appear in the Monthly Notices of the Royal Astronomical Society Letters in January 2008......... Posted by: Sean      Read more         Source

Tue, 04 Dec 2007 02:02:44 GMT

Cosmic Zoom

Apparently the inspiration for Powers of Ten, below is a YouTube version of Cosmic Zoom, directed by Canadian Eva Szasz, financed by the National Film Board of Canada.

(Hat tip: Kottke) Posted by: PhilipJ      Read more     Source