Posted on by Fraser Cain

What’s Up This Week – September 5 – September 11, 2005

NGC 6822. Image credit: Local Group Galaxies Team/NOAO/AURA/NSF. Click to enlarge.
Monday, September 5 – Tonight the Moon will be an exceptional sighting since it will only appear on the western horizon for a very short time after sunset. If you’re looking for a lunar challenge, then look no further than crater Petavius about one third the distance up from southern cusp. This ancient crater is a wonderland of details when on the terminator. Look for rugged walls interrupted by crater Wrottsley on the northwest corner and the elongated Palitzsch on the southeast. If conditions are stable, power up to look for a massive, multi-peaked central mountain region, along with with a deep scar – Rimae Petavius – cutting diagonally across the waved floor.

With the Moon leaving the scene well before full sky dark, our study for this evening is strictly a telescopic challenge for skilled observers. Set your sites about 2 degrees northeast of easy double 54 Sagittarii, and let’s have a look at NGC 6822.

Often referred to as “Barnard’s Galaxy”, for its discoverer (E.E. Barnard – 1884), this usual customer is actually a member of our local galaxy group. For the 4″ to 6″ telescope, this 1.7 million light year distant object will not be easy, but can be achieved with good conditions. Lower power is essential in even larger scopes, and those into the 12″ to 16″ range will see the NGC 6822 burst into stunning resolution. This author has found that “Barnard’s Galaxy” almost appears like an open cluster overlaid with nebulosity, but the experienced eye will clearly see that the “shine” behind the stars is galactic in nature. It’s a very clumpy and unusual galaxy – one that I think you will very much enjoy. Be sure to look for small, pale blue planetary nebula, NGC 6818 in the same field to the north/northwest. This pair rocks!

Tuesday, September 6 – Today celebrates the founding of the Astronomical and Astrophysical Society of America. Started in 1899, it is now known as the American Astronomical Society.

Tonight’s Moon will be very young. Can you spot its very slender crescent at twilight? You’ll find it less than two degrees away from Jupiter. If you chose to observe it, let’s go further south than last night’s study and have a look at Furnerius. Far more shallow and less impressive than Petavius, Furnerius will fade into obscurity as the days go by. This flooded old crater has no central peak, but it does have a much younger crater that has punched a hole in its lava-filled floor. Look for the long “crack” which extends from Furnerius’ north shore to the crater rim. Perhaps it was caused by the impact? Sharp-eyed observers with good conditions and high power will also spot a multitude of small craters both within and caught along Furnerius’ walls. For binocular viewers, can you spot challenging craters Stevenus to the north and Fraunhofer to the south?

Deep Sky binocular observers – I have not forgotten you. Although I cannot hand you an unusual study such as “Barnard’s Galaxy”, what I can point you toward is an open cluster in Cygnus that will look very similar. Aim your binoculars roughly halfway between Gamma (the central star in the “cross”) and Eta (the next brightest due south). The NGC 6871 is truly remarkable in low power, wide field instruments. You will see around a dozen 7th to 9th magnitude star set in an arc and the area will be surrounded by glow of cluster members beyond your resolution. For those who observe with only your eyes? You’ll see it as a brighter patch against the glow of the Milky Way. It’s a beauty!

Wednesday, September 7 – For our friends in southern Africa, tonight gives you an opportunity to witness an astounding event as the Moon occults brilliant Venus for your location. This is a “don’t miss” opportunity, so please check this IOTA webpages for times and locations. Wishing you the best!

For the rest of us? Don’t hide inside at sunset as the crescent Moon, Jupiter, Venus and Spica will make a wonderful appearance on the western horizon. Look for Venus less than a degree away from the Moon!

While we’re out, let’s have a look at the surface of Selene and head once again toward the confusing southern cusp. Tonight’s challenge will be an usual series of craters known as the Rheita Valley. Look for this unusual feature about one third the distance up from the southern cusp. On the terminator you will spy a collection of three craters which we will study at a later date – from north to south, Metius, Fabricus and Jannsen. From Metius, look northeast for the small crater with the thick walls and small central peak. This is Rheita. Along Rheita’s west wall, look for an unsual marking that appears to be a long runnel cut though the rugged terrain. This 500 kilometer long feature looks as though it might have been the result of a series of impacts that are much older than Rheita itself. You will notice that they appear to lap over one another, ending as they progress through older southern crater Young.

Thursday, September 8 – Today in 1966, a legend was born as the television program, “Star Trek” premiered. Its enduring legend, created by Gene Roddenberry, was instrumental to inspiring several generation’s interest in space, astronomy, and technology. The long running series still airs, along with many movie and series sequels. May it continue to “live long and prosper”.

Still hanging tough on sorting out southern lunar features? Then let’s challenge you a bit further as we head south again tonight in search of Piccolomini. Start by identifying the three-ring circus of Theophilus, Cyrillus and Catherina on the terminator at the western edge of Mare Nectaris. Remember our unofficially named lunar ridge, known as Dorsae Beaumont? Good. Then follow it south across Mare Nectaris and see where it ends in shallow crater Beaumont. Further south you will see the ruined ring of Fracastorius on the mare’s southern edge. Keep moving south, because the next major crater you see will be Piccolomini. This is one outstanding little crater with its very thick walls and brilliant central peak. Congratulations on identifying it!

Now, relax. Tonight the Piscid meteor stream will reach its expected maximum of around 5 meteors per hour. This particular shower favours the southern hemisphere. While this branch of the Piscids is a rather unstudied, unusual and diffuse stream that is active all month, the fairly early set of tonight’s Moon will aid you in keeping an eye out for “shooting stars” emanating in the southeast for the northern hemisphere viewers.

Friday, September 9 – In this day in 1839, John Herschel marks history as he made the very first glass plate photograph – and we’re glad he did! The photo was of the famous 40-foot telescope of John’s father, William Herschel. The scope had not been used in decades and was disassembled shortly after its photograph was taken. Later in 1892, one this same day, Edward Emerson Barnard was busy at Lick Observatory as he discovered Jupiter’s innermost moon – Amalthea.

So are you ready to tour the Southern Highlands again? Then let’s start by relocating full disclosed Theophilus, Cyrillus and Catherina. Head southwest until you spot a very magnificent old crater on the terminator. Congratulations! You’ve just identified Maurolycus. Look for several intruding craters on its northern and southern walls. Now power up! Inside of Maurolycus are several small interior punchmarks, but look closely at its southern and eastern wall. Can you see where the strike that formed Maurolycus has actually partially eclipsed a much older crater? Look at where the three come together, sharing a triple border with crater Barocius to the southeast.

Saturday, September 10 – Today is the birthday of James E. Keeler. Born in 1857, American Keeler was a pioneer in the field of spectroscopy and astrophysics. In 1895, Keeler proved that different areas in Saturn’s rings rotate at different velocities. This clearly showed the Saturn’s rings were not solid, but were instead a collection of smaller particles in independent orbit. Can you spot the “Ring King” in Gemini this morning before dawn?

Tonight for most observers, keep a watch on the waxing Moon as you’ll discover that Antares is less than half a degree away to the south.

And speaking of south, let’s walk the Highlands again! Tonight we are heading due west of Maurolycus for an awesome crater on the terminator – Stofler. Stofler is easy to recognize, because this is one battered crater with some very, very steep walls. Stofler itself is old, and probably would have had a smooth floor had it not been the site of some very nasty impacts. Look at its southeastern wall, where you will see two overlaying craters that are the result of meteoroids slamming into the surface. If that weren’t enough, look further at the southern wall where you will see that four more have punched holes in Stofler’s structure. The west wall is the last remaining untouched bridge, leaving the crater floor below it bathed in shadow from the lunar sunrise.

Sunday, September 11 – Today celebrates the birthday of Sir James Jeans. Born in 1877, English-born Jeans was an astronomical theoretician. During the beginning of the 20th century, Jeans worked out the fundamentals of gravitational collapse process. This is an important contribution to the understanding of the formation of solar systems, stars, and galaxies. With the 2005 success of Deep Impact, let’s turn back the hands of time. Twenty years ago on this date, ICE, the International Cometary Explorer, made history as it flew by Comet Giacobini-Zinner, making it the first mission to reach a comet.

Are you afraid to go south again? Then don’t be. Tonight we’ll be looking at a series of craters that lay along the terminator and border the emerging Mare Nubium. Staring just below the central point, look for a line of descending craters. From north to south, they are Ptlomaeus, Alphonsus, Arzachel, tiny Thebit, Purbach and Walter. Congratulations! You’ve learned more lunar features this week than most folks learn in a year. Be sure to look for Tycho even further south and right on the terminator. Tonight its resemblance to an old analog telephone dial is remarkable. Enjoy it now, because you won’t see it this way tomorrow!

Lunacy has returned. No problem! We’ll just study the Moon until skies turn dark again. Until then? May all your journeys be at light speed… ~Tammy Plotner

Posted on by Fraser Cain

Cassini Scientists Make New Ring Discoveries

Saturn Rings. Image credit: NASA/JPL/SSI Click to enlarge
Cassini scientists today (5th September 2005) announced a host of fantastic new results from the spacecraft’s first season of prime ring viewing, including some unexpected findings on Saturn’s rings. These include new structures in Saturn’s diffuse rings, clumps and knots in the F ring – some of which may be small moons – and a completely unexpected spiral ring around the planet in the vicinity of the F ring.

The findings are illustrated in processed images and movies being released today and found at http://ciclops.org, http://saturn.jpl.nasa.gov and http://www.nasa.gov/cassini.

First in the line of new discoveries is that parts of the D ring (Saturn’s innermost ring) have relocated and dimmed. Images show one of the major discrete ring structures in the D ring has changed in brightness and moved inward towards Saturn by as much as 200 kilometres (124 miles). A change over the 25 years since the NASA Voyager spacecraft flybys indicates very short evolutionary lifetimes in the D ring and is of great interest to ring scientists who have been hoping that Cassini would yield information about ring ages and lifetimes.

Dr. Matt Hedman, an imaging team associate at Cornell University, Ithaca, N.Y. said, “I think our Cassini images of the D ring are providing new information about the dynamics and lifetimes of ring particles in a new regime, very close to the planet.”

The delicate G ring encircles the planet at about 170,000 kilometres (106,000 miles) from Saturn’s centre. Cassini scientists have now found a discontinuous bright ring segment, or ‘arc’, in this ring that bear at least a fleeting similarity to those imaged around Neptune in 1989 by NASA’s Voyager 2 spacecraft. Scientists think that long-lived arcs may be created or maintained by a nearby hidden moon. Another thought is that they formed as a result of a meteoroid impact.

Saturn’s tenuous D and G rings contain very little material, and the tiny, icy particles are the size of dust or smoke.

In examining the intriguing, knotted F ring, imaging team scientists have also discovered that the ghostly ringlets flanking the ring’s core are arranged into a spiral structure wound like a spring around the planet. Other spiralling structures seen in the main rings of Saturn, the density and bending waves, are initiated by the gravitational influence of an orbiting moon.

Density and bending waves move across the rings because of the way that relatively massive ring particles exert a gravitational influence on each other and can all move together. In contrast, the spiral structure contains very little mass and appears to originate from material somehow episodically ejected from the core of the F ring and then sheared out due to the different orbital speeds followed by the constituent particles.

“It is a big surprise to see a spiral arm in Saturn’s rings,” said Dr. Sebastien Charnoz, imaging team associate at the University of Paris. “It is very possible that the spiral is a consequence of moons crossing the F ring and spreading particles around, and may be telling us that the F ring might be a very unstable or even an ephemeral structure.”

In the same region, scientists continue to spot small, clump-like features that may be loosely-bound clumps of material or tiny moonlets. Some of them have been sighted for the better part of a year. The solid-or-not nature of these mysterious F ring objects may be determined by repeated sightings: moons will persist, while clumps are expected to dissipate with time.

“We have long suspected that small moons were hiding among the F ring’s strands and producing some of the structures that we see,” said Imaging Team Member Professor Carl Murray of Queen Mary, University of London. “But now the problem is that we are detecting objects that may be either solid moons controlling the ring, or just loose clumps of particles within the ring, and it’s hard to tell the difference. It is like trying to distinguish sheep dogs from sheep in a very large flock.”

A puzzling characteristic of at least two of the clumps/moons is that they appear to cross the F ring periodically. One of them, an object that was discovered last year (S/2004 S6), may be responsible for forming the spiral.

“If the orbit that we have computed for S/2004 S6 is correct, then it must periodically plow through the core of the F ring,” said Dr. Joseph Spitale, an imaging team associate at the Space Science Institute in Boulder, Colo. “The details of that interaction are not understood, but there probably are observable consequences, and maybe the F ring spiral is one of them.”

These ring results were acquired over the summer as Cassini was in a prime ring-viewing period where the spacecraft’s orbit was raised to look down on the rings. The discoveries began almost immediately, with the discovery in May of a tiny moonlet orbiting within the narrow Keeler Gap in Saturn’s outer A ring.

These and other results were presented in a press briefing at the 37th Annual Meeting of the Division for Planetary Sciences meeting held this week in Cambridge, England.

Original Source: PPARC News Release

Posted on by Fraser Cain

Star Gobbles Up Its Friend

Artist’s impression of a pulsar ‘eating’ a companion star. Image credit: ESA Click to enlarge
ESA’s Integral space observatory, together with NASA’s Rossi X-ray Timing Explorer spacecraft, has found a fast-spinning pulsar in the process of devouring its companion.

This finding supports the theory that the fastest-spinning isolated pulsars get that fast by cannibalising a nearby star. Gas ripped from the companion fuels the pulsar’s acceleration. This is the sixth pulsar known in such an arrangement, and it represents a ‘stepping stone’ in the evolution of slower-spinning binary pulsars into faster-spinning isolated pulsars.
“We’re getting to the point where we can look at any fast-spinning, isolated pulsar and say, ‘That guy used to have a companion’,” said Dr Maurizio Falanga, who led the Integral observations, at the Commissariat ? l’Energie Atomique (CEA) in Saclay, France.

‘Pulsars’ are rotating neutron stars, which are created in stellar explosions. They are the remnants of stars that were once at least eight times more massive than the Sun. These stars still contain about the mass of our Sun compactified into a sphere of only about 20 kilometres across.

This pulsar, called IGR J00291+5934, belongs to a category of ‘X-ray millisecond pulsars’, which pulse with the X-ray light several hundred times a second, one of the fastest known. It has a period of 1.67 milliseconds which is much smaller that most other pulsars that rotate once every few seconds.

Neutron stars are born rapidly spinning in collapses of massive stars. They gradually slow down after a few hundred thousand years. Neutron stars in binary star systems, however, can reverse this trend and speed up with the help from the companion star.

For the first time ever, this speeding-up has been observed in the act. “We now have direct evidence for the star spinning faster whilst cannibalising its companion, something which no one had ever seen before for such a system,” said Dr Lucien Kuiper from the Netherlands Institute for Space Research (SRON), in Utrecht.

A neutron star can remove gas from its companion star in a process called ‘accretion’. The flow of gas onto the neutron star makes the star spin faster and faster. Both the flow of gas and its crashing upon the neutron star surface releases much energy in the form of X-ray and gamma radiation.

Neutron stars have such a strong gravitational field that light passing by the star changes its direction by almost 100 degrees (in comparison light passing by the Sun is deflected by an angle which is 200 thousands times smaller). “This ‘gravitational bending’ allows us to see the back side of the star,” points out Prof. Juri Poutanen from the University of Oulu, Finland.

“This object was about ten times more energetic than what is usually observed for similar sources,” said Falanga. “Only some kind of monster emits at these energies, which corresponds to a temperature of almost a billion degrees.”

From a previous Integral result, scientists deduced that because the neutron star has a strong magnetic field, charged particles from its companion are channeled along the magnetic field lines until they slam into the neutron star surface at one of its magnetic poles, forming ‘hot spots’. The very high temperatures seen by Integral arise from this very hot plasma over the accretion spots.

IGR J00291+5934 was discovered by Integral during a routine scan of the sky on 2 December 2004, in the outer reaches of our Milky Way galaxy, when it suddenly flared. On the day after, scientists accurately clocked the neutron star with the Rossi X-ray Timing Explorer.

Rossi observations revealed that the companion is already a fraction the size of our Sun, perhaps as small as 40 Jupiter masses. The binary orbit is 2.5 hours long (as opposed to the year long Earth-Sun orbit). The full system is very tight; both stars are so close that they will fit into the radius of the Sun. These details support the theory that the two stars are close enough for accretion to take place and that the companion star is being cannibalised.

“Accretion is expected to cease after a billion of years or so,” said Dr Duncan Galloway of the Massachusetts Institute of Technology, USA, responsible for the Rossi observations. “This Integral-Rossi discovery provides more evidence of how pulsars evolve from one phase to another – from an initially slowly spinning binary neutron star emitting high energies, to a rapidly spinning isolated pulsar emitting in radio wavelengths.”

The discovery is the first of its kind for Integral (four of the first five rapidly spinning X-ray pulsars were discovered by Rossi). This bodes well in the combined search for these rare objects. Integrals’s sensitive detectors can identify relatively dim and distant sources and so, knowing where to look, Rossi can provide timing information through a dedicated observation extending over the entire two-week period of the typical outburst.

Original Source: ESA Portal

Posted on by Fraser Cain

Pandora Shepherding the Rings

Moon Pandora from outside Saturn’s F ring. Image credit: NASA/JPL/SSI Click to enlarge
From just outside the faint edge of Saturn’s F ring, the moon Pandora keeps watch over her fine grained flock. The outer flanks of the F ring region are populated by ice particles approaching the size of the particles comprising smoke. As a shepherd moon, Pandora helps her cohort Prometheus confine and shape the main F ring. Pandora is 84 kilometers (52 miles) across.
Prometheus is 102 kilometers (63 miles) wide and orbits interior to the F ring.

The small knot seen attached to the core is one of several that Cassini scientists are eyeing as they attempt to distinguish embedded moons from transient clumps of material.

The image was taken with the Cassini spacecraft narrow-angle camera on Aug. 2, 2005, using a filter sensitive to wavelengths of infrared light centered at 930 nanometers at a distance of approximately 610,000 kilometers (379,000 miles) from Pandora and at a Sun-Pandora-spacecraft, or phase, angle of 146 degrees. Image scale is 4 kilometers (2 miles) per pixel.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA’s Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Original Source: NASA/JPL/SSI News Release

Posted on by Fraser Cain

Building Life from Star-Stuff

Supernova Remnant N 63A. Image credit: Hubble Click to enlarge
Life on Earth was made possible by the death of stars. Atoms like carbon and oxygen were expelled in the last few dying gasps of stars after their final supplies of hydrogen fuel were used up.

How this star-stuff came together to form life is still a mystery, but scientists know that certain atomic combinations were necessary. Water – two hydrogen atoms linked to one oxygen atom -was vital to the development of life on Earth, and so NASA missions now search for water on other worlds in the hopes of finding life elsewhere. Organic molecules built mostly of carbon atoms are also thought to be important, since all life on Earth is carbon-based.

The most popular theories of the origin of life say the necessary chemistry occurred at hydrothermal vents on the ocean floor or in some sunlit shallow pool. However, discoveries in the past few years have shown that many of the basic materials for life form in the cold depths of space, where life as we know it is not possible.

After dying stars belch out carbon, some of the carbon atoms combine with hydrogen to form polycyclic aromatic hydrocarbons (PAHs). PAHs — a kind of carbon soot similar to the scorched portions of burnt toast — are the most abundant organic compounds in space, and a primary ingredient of carbonaceous chondrite meteorites. Although PAHs aren’t found in living cells, they can be converted into quinones, molecules that are involved in cellular energy processes. For instance, quinones play an essential role in photosynthesis, helping plants turn light into chemical energy.

The transformation of PAHs occurs in interstellar clouds of ice and dust. After floating through space, PAH soot eventually condenses into these “dense molecular clouds.” The material in these clouds blocks out some but not all of the harsh radiation of space. The radiation that does filter through modifies the PAHs and other material in the clouds.

Infrared and radio telescope observations of the clouds have detected the PAHs, as well as fatty acids, simple sugars, faint amounts of the amino acid glycine, and over 100 other molecules, including water, carbon monoxide, ammonia, formaldehyde, and hydrogen cyanide.

The clouds have never been sampled directly — they’re too far away — so to confirm what is occurring chemically in the clouds, a research team led by Max Bernstein and Scott Sandford at the Astrochemistry Laboratory at NASA’s Ames Research Center set up experiments to mimic the cloud conditions.

In one experiment, a PAH/water mixture is vapor-deposited onto salt and then bombarded with ultraviolet (UV) radiation. This allows the researchers to observe how the basic PAH skeleton turns into quinones. Irradiating a frozen mixture of water, ammonia, hydrogen cyanide, and methanol (a precursor chemical to formaldehyde) generates the amino acids glycine, alanine and serine — the three most abundant amino acids in living systems.

Scientists have created primitive organic cell-like structures, or vesicles.

Because UV is not the only type of radiation in space, the researchers also have used a Van de Graaff generator to bombard the PAHs with mega-electron volt (MeV) protons, which have similar energies to cosmic rays. The MeV results for the PAHs were similar although not identical to the UV bombardment. A MeV study for the amino acids has not yet been conducted.

These experiments suggest that UV and other forms of radiation provide the energy needed to break apart chemical bonds in the low temperatures and pressures of the dense clouds. Because the atoms are still locked in ice, the molecules don’t fly apart, but instead recombine into more complex structures.

In another experiment led by Jason Dworkin, a frozen mixture of water, methanol, ammonia and carbon monoxide was subjected to UV radiation. This combination yielded organic material that formed bubbles when immersed in water. These bubbles are reminiscent of cell membranes that enclose and concentrate the chemistry of life, separating it from the outside world.

The bubbles produced in this experiment were between 10 to 40 micrometers, or about the size of red blood cells. Remarkably, the bubbles fluoresced, or glowed, when exposed to UV light. Absorbing UV and converting it into visible light in this way could provide energy to a primitive cell. If such bubbles played a role in the origin of life, the fluorescence could have been a precursor to photosynthesis.

Fluorescence also could act as sunscreen, diffusing any damage that otherwise would be inflicted by UV radiation. Such a protective function would have been vital for life on the early Earth, since the ozone layer, which blocks out the sun’s most destructive UV rays, did not form until after photosynthetic life began to produce oxygen.

From space clouds to the seeds of life

Dense molecular clouds in space eventually gravitationally collapse to form new stars. Some of the leftover dust later clumps together to form asteroids and comets, and some of these asteroids clump together to form planetary cores. On our planet, life then arose from whatever basic materials were at hand.

The large molecules necessary to build living cells are:

* Proteins
* Carbohydrates (sugars)
* Lipids (fats)
* Nucleic acids

Meteorites have been found to contain amino acids (the building blocks of proteins), sugars, fatty acids (the building blocks of lipids), and nucleic acid bases. The Murchison meteorite, for instance, contains chains of fatty acids, various types of sugars, all five nucleic acid bases, and more than 70 different amino acids (life uses 20 amino acids, only six of which are in the Murchison meteorite).

Because such carbonaceous meteorites are generally uniform in composition, they are thought to be representative of the initial dust cloud from which the sun and solar system were born. So it seems that nearly everything needed for life was available at the beginning, and meteorites and comets then make fresh deliveries of these materials to the planets over time.

If this is true, and if molecular dust clouds are chemically similar throughout the galaxy, then the ingredients for life should be widespread.

The downside of the abiotic production of the ingredients for life is that none of them can be used as “biomarkers,” indicators that life exists in a particular environment.

Max Bernstein points to the Alan Hills meteorite 84001 as an example of biomarkers that didn’t provide proof of life. In 1996, Dave McKay of NASA’s Johnson Space Center and his colleagues announced there were four possible biomarkers within this martian meteorite. ALH84001 had carbon globules containing PAHs, a mineral distribution suggestive of biological chemistry, magnetite crystals resembling those produced by bacteria, and bacteria-like shapes. While each alone was not thought to be evidence for life, the four in conjunction seemed compelling.

After the McKay announcement, subsequent studies found that each of these so-called biomarkers also could be produced by non-living means. Most scientists therefore are now inclined to believe that the meteorite does not contain fossilized alien life.

“As soon as they had the result, people went gunning for them because that’s the way it works,” says Bernstein. “Our chances of not making an error when we come up with a biomarker on Mars or on Europa will be much better if we’ve already done the equivalent of what those guys did after McKay, et al., published their article.”

Bernstein says that by simulating conditions on other planets, scientists can figure out what should be happening there chemically and geologically. Then, when we visit a planet, we can see how closely reality matches the predictions. If there’s anything on the planet that we didn’t expect to find, that could be an indication that life processes have altered the picture.

“What you have on Mars or on Europa is material that’s been delivered,” says Bernstein. “Plus, you have whatever has formed subsequently from whatever conditions are present. So (to look for life), you need to look at the molecules that are there, and keep in mind the chemistry that may have happened over time.”

Bernstein thinks chirality, or a molecule’s “handedness,” could be a biomarker on other worlds. Biological molecules often come in two forms that, while chemically identical, have opposite shapes: a “left-handed” one, and its mirror image, a “right-handed” one. A molecule’s handedness is due to how the atoms bond. While handedness is evenly dispersed throughout nature, in most cases living systems on Earth have left-handed amino acids and right-handed sugars. If molecules on other planets show a different preference in handedness, says Bernstein, that could be an indication of alien life.

“If you went to Mars or Europa and you saw a bias the same as ours, with sugars or amino acids having our chirality, then people would simply suspect it was contamination,” says Bernstein. “But if you saw an amino acid with a bias towards the right, or if you saw a sugar that had a bias towards the left — in other words, not our form — that would be really compelling.”

However, Bernstein notes that the chiral forms found in meteorites reflect what is seen on Earth: meteorites contain left-handed amino acids and right-handed sugars. If meteorites represent the template for life on Earth, then life elsewhere in the solar system also may reflect that same bias in handedness. Thus, something more than chirality may be needed for proof of life. Bernstein says that finding chains of molecules, “such as a couple of amino acids linked together,” also could be evidence for life, “because in meteorites we tend to just see single molecules.”

Original Source: NASA Astrobiology

Posted on by Fraser Cain

The New Forum is Online

As I mentioned a few days ago, Phil Plait from Bad Astronomy and I have decided to merge our two forums into one super-space forum. The new forum is now live, and accessible from http://www.bautforum.com. This new forum has more than 10,000 members, and almost 550,000 posts.

Although the forum is functional and ready for conversations, we’ll still be tweaking it over the next few days, weeks, months. Let us know if you find any bugs. Please also let us know if you’re having any problems logging in with your username.

I look forward to seeing you there.

Fraser Cain
Publisher
Universe Today

Posted on by Fraser Cain

Researchers find clue to start of universe

Station with active crossed dipole. Image credit: Haystack Observatory Click to enlarge
If you want to hear a little bit of the Big Bang, you’re going to have to turn down your stereo.

That’s what neighbors of MIT’s Haystack Observatory found out. They were asked to make a little accommodation for science, and now the results are in: Scientists at Haystack have made the first radio detection of deuterium, an atom that is key to understanding the beginning of the universe. The findings are being reported in an article in the Sept. 1 issue of Astrophysical Journal Letters.

The team of scientists and engineers, led by Alan E.E. Rogers, made the detection using a radio telescope array designed and built at the MIT research facility in Westford, Mass. Rogers is currently a senior research scientist and associate director of the Haystack Observatory.

After gathering data for almost one year, a solid detection was obtained on May 30.

The detection of deuterium is of interest because the amount of deuterium can be related to the amount of dark matter in the universe, but accurate measurements have been elusive. Because of the way deuterium was created in the Big Bang, an accurate measurement of deuterium would allow scientists to set constraints on models of the Big Bang.

Also, an accurate measurement of deuterium would be an indicator of the density of cosmic baryons, and that density of baryons would indicate whether ordinary matter is dark and found in regions such as black holes, gas clouds or brown dwarfs, or is luminous and can be found in stars. This information helps scientists who are trying to understand the very beginning of our universe.

Until now the deuterium atom has been extremely difficult to detect with instruments on Earth. Emission from the deuterium atom is weak since it is not very abundant in space-there is approximately one deuterium atom for every 100,000 hydrogen atoms, thus the distribution of the deuterium atom is diffuse. Also, at optical wavelengths the hydrogen line is very close to the deuterium line, which makes it subject to confusion with hydrogen; but at radio wavelengths, deuterium is well separated from hydrogen and measurements can provide more consistent results.

In addition, our modern lifestyle, filled with gadgets that use radio waves, presented quite a challenge to the team trying to detect the weak deuterium radio signal. Radio frequency interference bombarded the site from cell phones, power lines, pagers, fluorescent lights, TV, and in one case from a telephone equipment cabinet where the doors had been left off. To locate the interference, a circle of yagi antennas was used to indicate the direction of spurious signals, and a systematic search for the RFI sources began.

At times, Rogers asked for help from Haystack’s neighbors, and in several instances replaced a certain brand of answering machine that was sending out a radio signal with one that did not interfere with the experiment. The interference caused by one person’s stereo system was solved by having a part on the sound card replaced by the factory.

The other members of the team working with Rogers are Kevin Dudevoir, Joe Carter, Brian Fanous and Eric Kratzenberg (all of Haystack Observatory) and Tom Bania of Boston University.

The Deuterium Array at Haystack is a soccer-field size installation conceived and built at the Haystack facility with support from the National Science Foundation, MIT and TruePosition Inc.

Original Source: MIT News Release

Posted on by Fraser Cain

Hubble’s Neptune Movies

Blue-green Neptune and its satellites. Image credit: NASA/ESA Click to enlarge
New NASA Hubble Space Telescope images of the distant planet Neptune show a dynamic atmosphere and capture the fleeting orbits of its satellites. The images have been assembled into a time-lapse movie revealing the orbital motion of the satellites.

Images were taken in 14 different colored filters probing various altitudes in Neptune’s deep atmosphere so that scientists can study the haze and clouds in detail.

These are several snapshots from the Neptune movie.

The natural-color view of Neptune (to left), common to naked eye telescopic views by amateur astronomers, reveals a cyan colored planet. Methane gas in Neptune’s atmosphere absorbs most of the red sunlight hitting the planet, making it look blue-green. The image was created by combining images in red, green, and blue light.

Neptune’s subtle features are more visible in the enhanced-color view (top right). Images taken in special methane filters show details not visible to the human eye (bottom right). The features seen in this enhanced image must be above most of the sunlight-absorbing methane to be detectable through these special filters.

The planet is so dark at the methane wavelengths that long exposures can be taken, revealing some of Neptune’s smaller moons. Clockwise from the top (in composite image at left), these moons are Proteus (the brightest), Larissa, Despina, and Galatea. Neptune had 13 moons at last count.

Neptune is the most distant giant planet in our Solar System, orbiting the Sun every 165 years. It is so large tht nearly 60 Earths could fit inside it. A day on Neptune is between 14 hours and 19 hours. The inner two thirds of Neptune is composed of a mixture of molten rock, water, liquid ammonia and methane. The outer third is a mixture of heated gases comprised of hydrogen, helium, water and methane.

On April 29 and 30, 2005, Hubble images were taken every 4-5 hours, spaced at about a quarter of Neptune’s rotational period. These where combined to create a time-lapse movie of the dynamic planet.

Original Source: Hubble News Release

Posted on by Fraser Cain

Giant South African Telescope Online

NGC 6744 taken by SALT. Image credit: SALT Click to enlarge
Five years after breaking ground on a South African mountaintop near the edge of the Kalahari desert, astronomers today (Sept. 1, 2005) released the first images captured by the Southern African Large Telescope (SALT), now the equal of the world’s largest optical telescope and a prized window to the night skies of the southern hemisphere.

With a 10- by 11-meter hexagonal segmented mirror and state-of-the-art scientific instrumentation, the new telescope was constructed by an international consortium of universities and government agencies. Partners include the National Research Foundation of South Africa, UW-Madison’s College of Letters and Science, Poland’s Nicolas Copernicus Astronomical Centre and Rutgers University, among others.

The new $18 million observatory will provide unprecedented access to the astronomically rich skies of the southern hemisphere. Objects such as the Large and Small Magellanic Clouds, the galaxies nearest to our own Milky Way, will come into sharp view through the concerted focus of the 91 hexagonal mirror segments that comprise the SALT Telescope’s primary mirror array.

“We’re now players in the world of large telescopes,” says Eric Wilcots, a UW-Madison professor of astronomy. “We’re in an age in which answering the big, fundamental questions requires access to large telescopes in good, dark skies. SALT is just such a telescope.”

Access to the southern sky, says Wilcots, promises a bounty of observing: “The southern Milky Way is more spectacular and provides a richer treasure trove of objects than the northern Milky Way.”

Moreover, studies of thousands of individual stars in the Magellanic Clouds are planned to trace the history of those nearby galaxies. The results of those studies, Wilcots explains, can be extrapolated to galaxies in general, providing a more refined life history of objects like our own Milky Way.

Other southern sky objects of interest, according to Kenneth Nordsieck, a UW-Madison astronomer now in South Africa to help with the SALT Telescope’s commissioning, include Eta Carina, a nearby massive star that has been racked by a series of enigmatic and spectacular explosions over the past century; Omega Centauri, a globular cluster of stars in the Milky Way that some astronomers believe may be the fossil remains of another galaxy consumed long ago by the Milky Way; and Centaurus A, a nearby galaxy that recently experienced an explosion at its core.

A critical advantage for the SALT Telescope, according to astronomers, is its location in one of the darkest regions of the world. With no nearby cities or towns, the observatory will be little affected by the light pollution that seriously hampers many observatories in the Northern Hemisphere.

Together with Rutgers University, another member of the SALT consortium, Wisconsin astronomers and engineers have constructed and are now integrating into the observatory the primary scientific instrument for the telescope, a device known as the Prime Focus Imaging Spectrograph. When in place six stories above the primary mirror array, the $5 million device will give the SALT Telescope specialized capabilities to capture and analyze starlight in unprecedented ways.

Spectrometers are designed to parse light into its constituent wavelengths. The spectra they obtain are revealing, providing astronomers with far more information than simple images. They can help show the chemical makeup of objects, depict motion, and some wavelengths of light enable astronomers to see through the obscuring clouds of dust and gas that permeate space.

One specialized capability of the Prime Focus Imaging Spectrograph, according to Nordsieck, is the ability to make observations in the near ultraviolet, the same kind of light that causes sunburn. “This is one of the few big instruments that will be good in the ultraviolet,” says Nordsieck.

The images released today through the South African Astronomical Observatory, the SALT Observatory’s parent organization, were taken with a digital camera known as SALTICAM. They include stunning pictures of the Lagoon Nebula, a luminous stellar nursery; the globular star cluster 47 Tucanae; and NGC6744, a barred spiral galaxy that astronomers consider almost a twin of our own Milky Way.

“The declaration of first light signifies that SALT has arrived on the astronomical scene,” according to a statement issues by the South African Astronomical Observatory. Although a months-long period of commissioning and shakedown remains, “SALT is now in a very real sense an operational telescope.”

A critical upcoming milestone will be the integration of the Wisconsin-built Prime Focus Imaging Spectrograph, envisioned as the workhorse instrument for the SALT Telescope. Capable of capturing high-resolution pictures, movies and the telltale spectra of objects such as stars, galaxies and comets, the device will be perched high above the light gathering primary mirror array at the heart of the new telescope.

Installation is expected in mid-September. “It is progressing in fits and starts, about the way one would expect with something of this complexity,” says Nordsieck. “In the meantime, the telescope team has worked out a lot of kinks so there should be a relatively smooth commissioning.”

The development of the SALT Observatory, says Wilcots, is “a beacon for Southern African science. It is meant to inspire a new generation of African scientists, which will be the lasting value of SALT to Southern Africa.”

For UW-Madison, the telescope project represents a bridge from Madison to South Africa. “Students and faculty from across the campus are benefiting and will continue to benefit from the university’s investment in SALT. We now have a student exchange program with the University of Cape Town and we will be initiating an exchange with the University of the Western Cape in November,” says Wilcots.

He emphasizes that the South Africans are making a statement with their investment in the giant telescope. “It is meant to showcase the capability of Southern African scientists and engineers – and it has done that,” Wilcots says. “Keep in mind that there are only a handful, perhaps as few as three, black South Africans with Ph.Ds in astronomy. While we have problems with an underrepresented minority in science, South Africa has an under-represented majority.”

Original Source: UW-Madison News Release

Posted on by Fraser Cain

Rings from the Unlit Side

Saturn’s rings from their unlit side. Image credit: NASA/JPL/SSI Click to enlarge
This magnificent view looks down upon, and partially through, Saturn’s rings from their unlit side.
The densest part of the rings occults the bright globe of Saturn. Scientists can use observations like this to determine precisely the concentration of ring particles.

When the bright source is the signals coming from the spacecraft, the technique is called a ‘radio occultation.’ In a radio occultation measurement, a signal is beamed toward Earth from Cassini’s 4-meter-wide (13-foot) high-gain antenna. Researchers on Earth receive the signal as the spacecraft passes behind the rings. The reduction in Cassini’s radio signal tells researchers how densely packed the ring particles are. Scientists can also learn about the size distributions of the particles from occultations.

As an added (but tiny) bonus, Saturn’s moon Atlas (32 kilometers, or 20 miles across) is visible as a dark speck against the planet, just outside the A ring.

The image was taken in visible red light with the Cassini spacecraft wide-angle camera on Aug. 2, 2005, at a distance of approximately 617,000 kilometers (383,000 miles) from Saturn. The image scale is 37 kilometers (23 miles) per pixel.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA’s Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Original Source: NASA/JPL/SSI News Release