October 24, 2006, 7:26 PM CT

New Theory For Mass Extinctions

A new theory on just what causes Earth's worst mass extinctions may help settle the endless scientific dust-up on the matter. Whether you favor meteor impacts, volcanic eruptions, cosmic rays, epidemics, or some other cause for the worst mass extinction events in Earth's history, no single cause has ever satisfied all researchers all the time for any extinction event. That may be because big extinctions aren't simple events.

The new Press/Pulse theory gets around the controversy by rejecting the all-or-nothing approach to mass extinction, calling instead on a combination of deadly sudden catastrophes - "pulses" - with longer, steadier pressures on species - "presses".

"What we wanted to do is move away from the idiosyncratic approach to extinction mechanisms and look for what these intervals had in common. If you have A and B you will get a mass extinction," said Ian West, a 2006 graduate of Hobart and William Smith Colleges in Geneva, NY.

West and Hobart and William Colleges paleontology professor Nan Crystal Arens are scheduled to present their work on the Press/Pulse theory on Wednesday, 25 October, at the Annual Meeting of the Geological Society of America in Philadelphia.

Using databases that chart genera of marine organisms and their extinctions through the fossil record, West and Arens divided the last 488 million years of geologic history into four groups: times of suspected impact events (Pulses), times of massive volcanic eruptions (Presses), times when neither Presses nor Pulses occurred, and times when Press and Pulse coincided. They compared average extinction rates in geologic stages in each of these groups.........

Posted by: William      Permalink         Source

October 16, 2006, 9:36 PM CT

Day And Night On The Exotic World

NASA's Spitzer Space Telescope has made the first measurements of the day and night temperatures of a planet outside our solar system. The infrared observatory revealed that the Jupiter-like gas giant planet circling very close to its sun is always as hot as fire on one side, and potentially as cold as ice on the other.

"This planet has a giant hot spot in the hemisphere that faces the star," said Dr. Joe Harrington of the University of Central Florida, Orlando, lead author of a paper appearing online today in Science. "The temperature difference between the day and night sides tells about how energy flows in the planet's atmosphere. Essentially, we're studying weather on an exotic planet".

The finding represents the first time any kind of variation has been seen across the surface of an extrasolar planet, a planet beyond our solar system. Previous measurements of extrasolar planets described only global traits like size and mass.

"This is a spectacular result," said Dr. Michael Werner, project scientist for Spitzer at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "When we designed Spitzer years ago, we did not anticipate that it would be revolutionizing extrasolar-planet science".

The researchers used Spitzer to determine the temperature variation in the atmosphere of a nearby planet called Upsilon Andromedae b. This "hot-Jupiter" planet is a gas giant similar to Jupiter, but it orbits very close to its scorching star, circling the star once every 4.6 days.........

Posted by: Brooke      Permalink         Source

October 12, 2006, 8:11 PM CT

Headcount Of Local Black Holes

NASA scientists using the Swift satellite have conducted the first complete census of galaxies with active, central black holes, a project that scanned the entire sky several times over a nine-month period.

The all-sky survey contains more than 200 supermassive black holes called Active Galactic Nuclei, or AGN, and provides a definitive census of black hole activity in the local universe. The team uncovered many new black holes that were previously missed, even in well-studied galaxies, and other surprises as well.

"We are confident that we are seeing every active, supermassive black hole within 400 million light years of Earth," said Jack Tueller of NASA's Goddard Space Flight Center, Greenbelt, Md., who led the effort. "With each passing month, we are able to probe deeper into the universe, and the census becomes richer".

AGN have a mass of millions to billions of suns, which are confined within a region about the size of our solar system. The term "active" refers to the process of actively pulling in gas and whole stars and generating copious amounts of energy from a tiny galactic core in the process. Examples include quasars and Seyfert galaxies.

Swift was built primarily to study gamma-ray bursts. During waiting times between bursts, Swift's Burst Alert Telescope, which is sensitive to the highest-energy X-rays, scans the sky. AGN generate X-rays as well as many other forms of light. Many AGN, however, are hidden behind dust and gas, which block lower-energy light, such as visible light. Because higher-energy X-rays are so penetrating, Swift can detect AGN missed by other surveys, allowing for an unbiased count.........

Posted by: Brooke      Permalink         Source

October 12, 2006, 7:48 PM CT

Jupiter's Little Red Spot Growing Stronger

The highest wind speeds in Jupiter's Little Red Spot have increased and are now equal to those in its older and larger sibling, the Great Red Spot, according to observations with NASA's Hubble Space Telescope.

The Little Red Spot's winds, now raging up to approximately 400 miles per hour, signal that the storm is growing stronger, according to the NASA-led team that made the Hubble observations. The increased intensity of the storm probably caused it to change color from its original white in late 2005, according to the team.

"No one has ever seen a storm on Jupiter grow stronger and turn red before," said Amy Simon-Miller of NASA's Goddard Space Flight Center, Greenbelt, Md., lead author of a paper describing the new observations appearing in the journal Icarus. "We hope continued observations of the Little Red Spot will shed light on the many mysteries of the Great Red Spot, including the composition of its clouds and the chemistry that gives it its red color".

Although it seems small when viewed against Jupiter's vast scale, the Little Red Spot is actually about the size of Earth, and the Great Red Spot is around three Earth diameters across. Both are giant storms in Jupiter's southern hemisphere powered by warm air rising in their centers.

The Little Red Spot is the only survivor among three white-colored storms that merged together. In the 1940s, the three storms were seen forming in a band slightly below the Great Red Spot. In 1998, two of the storms merged into one, which then merged with the third storm in 2000. In 2005, amateur astronomers noticed that this remaining, larger storm was changing color, and it became known as the Little Red Spot after becoming noticeably red in early 2006.........

Posted by: Brooke      Permalink         Source

October 12, 2006, 5:04 AM CT

Evidence Of A Modern-day Collision

Scientists on NASA's Cassini mission have spied a new, continuously changing feature that provides circumstantial evidence that a comet or asteroid recently collided with Saturn's innermost ring, the faint D ring.

Imaging scientists see a structure in the outer part of the D-ring that looks like a series of bright ringlets with a regularly spaced interval of about 30 kilometers (19 miles). An observation made by NASA's Hubble Space Telescope in 1995 also saw a periodic structure in the outer D ring, but its interval was then 60 kilometers (37 miles). Thus, unlike many features in the ring system which have not changed over the last few decades, the interval of this pattern has been decreasing over time.

These findings are being presented today at the Division for Planetary Sciences Meeting of the American Astronomical Society held in Pasadena, Calif. Images are available at http://ciclops.org, http://www.nasa.gov/cassini, and http://saturn.jpl.nasa.gov.

"This structure in the D ring reminds us that Saturn's rings are not eternal, but instead are active, dynamical systems, which can change and evolve," said faint ring specialist, Dr. Matt Hedman, Cassini imaging team associate at Cornell University, Ithaca, N.Y.

When Cassini researchers viewed the D ring along a line of sight nearly parallel to the ringplane, they observed a pattern of brightness reversals: a part of the ring that appears bright on the far side of the rings appeared dark on the near side of the rings, and vice versa.........

Posted by: Brooke      Permalink         Source

October 8, 2006, 6:56 PM CT

Back From Deep Hibernation

Cluster 2, Artist's view
On 15 September, flight controllers at ESA's Space Operations Centre watched tensely as 'Rumba', No. 1 in the four-spacecraft Cluster fleet, was switched into a low-power, deep hibernation mode. The aim was to survive a challenging eclipse.

Each year, in autumn, the Cluster fleet must pass several times through the Earth's shadow with respect to the Sun. During these eclipses, which last about three hours, sunlight is blocked by the Earth and the spacecraft solar panels cannot generate electricity.

Batteries then generate electrical power, which is used to run heaters - keeping the spacecraft warm - and to operate on-board computers and maintain spacecraft control.

However, the Cluster fleet, launched in mid-2000, has been in orbit for over six years and batteries, in particular, are beginning to age. This year, spacecraft No. 1, Rumba, had the most severe battery problems; three out of five have already been declared non-operational for nominal use and one has a high leakage current.

As a result, mission engineers forecast that only about half of the battery power required by Rumba would be available during eclipse season.

ESOC, ESTEC, industry team solves power shortfall

The pending power shortfall was recognized in 2005, and an interdisciplinary team of engineers comprising representatives from the Flight Control Team at the European Space Operations Centre (ESOC), researchers at ESA's Research and Technology Centre (ESTEC) and the spacecraft's builder was established to devise a solution.........

Posted by: Brooke      Permalink         Source

September 20, 2006, 8:03 PM CT

Droids in the Desert

Image above: In one scenario of the Desert Research and Technology Studies in the Arizona desert, a test subject returns to a mock way station. Credit: NASA
Arizona tourists may think they've stumbled upon a science fiction movie set if they find themselves near the state's famed Meteor Crater in early September.

Though they won't get a glimpse of R2D2 or C3PO, they will see robots, rovers and space suited subjects with the latest interplanetary gear trekking over some of the state's harshest topography.

For two weeks a year, the stark Arizona landscape becomes a surrogate planet for NASA scientists. Why? Well, you can only do so much in a laboratory and it's a long way to Mars.

The temperature extremes, gusty winds and grit and dust of Arizona's high desert make it an ideal location to field test and evaluate prototype planetary exploration gear.

So, now it is exam time for NASA's Desert Research and Technology Studies (RATS), a team of researchers and engineers who test futuristic equipment that may one day be used for explorations of the moon and Mars.

This is the ninth year for Desert RATS to test a variety of advanced prototype equipment and operational concept techniques. The two-week trials will be conducted Sept. 4 -16 on remote field sites near the crater.

"Field tests like these are much like a final exam," said Johnson Space Center's Joe Kosmo, who leads the team. "We know what works on paper or in the laboratory, but what works there may not work in the field, or it may work differently than expected. Field testing offers a hands-on experience base that is important as we strive to design and operate these emerging planetary surface technologies."........

Posted by: Tyler      Permalink         Source

September 14, 2006, 6:44 PM CT

Spiral Galaxy in Triangulum

The small, northern constellation Triangulum harbors this magnificent face-on spiral galaxy, M33. Its popular names include the Pinwheel Galaxy or just the Triangulum Galaxy. M33 is over 50,000 light-years in diameter, third largest in the Local Group of galaxies after the Andromeda Galaxy (M31), and our own Milky Way.

About 3 million light-years from the Milky Way, M33 is itself thought to be a satellite of the Andromeda Galaxy and astronomers in these two galaxies would likely have spectacular views of each other's grand spiral star systems. As for the view from planet Earth, this detailed, wide field image nicely shows off M33's blue star clusters and pinkish star forming regions which trace the galaxy's loosely wound spiral arms. In fact, the cavernous NGC 604 is the brightest star forming region, seen here at about the 1 o'clock position from the galaxy center. Like M31, M33's population of well-measured variable stars have helped make this nearby spiral a cosmic yardstick for establishing the distance scale of the Universe.........

Posted by: Brooke      Permalink         Source

September 14, 2006, 4:35 AM CT

Einstein at least 99.95 percent right

An international research team led by Prof. Michael Kramer of the University of Manchester's Jodrell Bank Observatory, UK, has used three years of observations of the "double pulsar", a unique pair of natural stellar clocks which they discovered in 2003, to prove that Einstein's theory of general relativity - the theory of gravity that displaced Newton's - is correct to within a staggering 0.05%. Their results are published on the14th September in the journal Science and are based on measurements of an effect called the Shapiro Delay.

The double pulsar system, PSR J0737-3039A and B, is 2000 light-years away in the direction of the constellation Puppis. It consists of two massive, highly compact neutron stars, each weighing more than our own Sun but only about 20 km across, orbiting each other every 2.4 hours at speeds of a million kilometres per hour. Separated by a distance of just a million kilometres, both neutron stars emit lighthouse-like beams of radio waves that are seen as radio "pulses" every time the beams sweep past the Earth. It is the only known system of two detectable radio pulsars orbiting each other. Due to the large masses of the system, they provide an ideal opportunity to test aspects of General Relativity:

• Gravitational redshift: the time dilation causes the pulse rate from one pulsar to slow when near to the other, and vice versa.

........

Posted by: Jaison      Permalink         Source

September 10, 2006, 6:54 AM CT

Latest Astrophotos

Amazing pictures of the moon captured with EOS-20D digital camera.

Quote from the website:

Stacked from 15 exposures of 1/5 second at ISO 100 This image is a mosaic of 15 separate and slightly overlapping 8.2 megapixel images from my Canon EOS-20D (unmodified), taken in Raw mode and converted and stitched together in Photoshop CS2. The exposures were each 1/5 second at ISO 100.

I mounted my 20D to my Meade LX200 GPS UHTC 10" Schmidt-Cassegrain telescope via my 2x Televue Powermate (a focal length doubler, similar to a teleconverter, which also serves to mate my camera to the 2" telescope eyepiece tube). Effective focal length was 5000mm f/20.

Looking through the viewfinder I swept across the surface in a zig-zag fashion, trying for about 1/3 overlap between frames. I triggered the shutter with my TC80-N3 remote timer/controller. I did the stitching by hand in Photoshop.

End of quote:

Thank you.........

Posted by: Brooke      Permalink         Source