Posted on by Fraser Cain

Measures to Prevent the Contamination of Mars

Crater Holden and Uzboi Vallis. Image credit: ESA/DLR/FU Berlin. Click to enlarge
Over the coming decade, NASA should develop and implement new methods and requirements to detect and eliminate microorganisms on robotic spacecraft sent to Mars to prevent possible contamination of the planet, says a new report from the National Academies’ National Research Council. If microbes aboard a spacecraft were to survive the trip to Mars and grow there, they could interfere with scientific investigations to detect any life that might be native to Mars. Existing techniques for cleaning spacecraft are outdated and typically eliminate only a fraction of microorganisms, said the committee that wrote the report.

Recent scientific findings suggest that liquid water could be present at many locations on Mars and that some organisms on Earth might survive in extreme, Mars-like conditions — such as very low temperatures and high salt concentrations. These discoveries have bolstered the case that Mars could be — or have been — hospitable to life and have created urgency to update policies and practices to prevent Mars contamination, the report says.

“Ongoing Mars missions have shown that the planet may have environments where some Earth microbes could grow,” said Christopher F. Chyba, committee chair and professor of astrophysics and international affairs at Princeton University, Princeton, N.J. “Although we don’t know for sure if this could happen, we need to understand whether liquid water exists in Martian near-surface environments, as well as the nature of microorganisms that are in our clean rooms and spacecraft. It will take a while to carry out the needed research and development, so we need to start in earnest now.”

NASA currently uses screening techniques that detect heat-resistant and spore-forming bacteria on spacecraft and then reduces their numbers by cleaning the spacecraft and, in certain circumstances, baking components with dry heat. But these screening methods are not designed to give a comprehensive tally of the microbes present on the spacecraft, and dry heat can be applied only to spacecraft materials that can withstand high temperatures, the report notes.

NASA should sponsor new research efforts aimed at preventing Mars contamination, the committee said, such as new techniques for detecting biological molecules that do not require time for growing laboratory cultures and could speed spacecraft sterilization and assembly in clean rooms. Also, methods that determine genetic sequences of organisms and link them to known microbial species could allow NASA to tailor sterilization techniques toward spacecraft contaminants of greatest concern. NASA should also investigate alternative cleaning methods — such as the use of radiation or vapor disinfectants — for their effectiveness in killing different types of microorganisms and for their effects on various spacecraft materials.

NASA should develop a certification process to compare detection and cleaning methods and select the most promising ones, begin testing and validating improved techniques within the next three years, and fully implement selected new techniques in time for spacecraft to launch in 2016. Until NASA conducts the research needed to transition to a modern approach for planetary protection, the agency should apply more stringent sterilization levels to all Mars landing spacecraft, the committee said. An independent review panel should be created by NASA and meet every three years to review new knowledge about the Martian environment and recommend updates, as needed, to Mars protection requirements.

The study was sponsored by NASA. The National Research Council is the principal operating arm of the National Academy of Sciences and the National Academy of Engineering. It is a private, nonprofit institution that provide science and technology advice under a congressional charter. A committee roster follows.

Original Source: The National Academies News Release

Posted on by Fraser Cain

Strange Ice Boulders on Enceladus

The southern polar terrain of Enceladus. Image credit: NASA/JPL/SSI. Click to enlarge
NASA’s Cassini spacecraft has obtained new, detailed images of the south polar region of Saturn’s moon Enceladus. The data reveal distinctive geological features and the most youthful terrain seen on the moon. These findings point to a very complex evolutionary history for Saturn’s brightest, whitest satellite.

Cassini’s July 14 flyby brought it within 175 kilometers (109 miles) of the surface of the icy moon. The close encounter revealed a landscape near the south pole almost entirely free of impact craters. The area is also littered with house-sized ice boulders carved by unique tectonic patterns found only in this region of the moon.

As white as fresh snow, Enceladus has the most reflective surface in the solar system. Previous Cassini flybys revealed Enceladus, in contrast to Saturn’s other icy moons, has lightly cratered regions, fractured plains and wrinkled terrain.

The new findings add to the story of a body that has undergone multiple episodes of geologic activity spanning a considerable portion of its lifetime. The moon’s southernmost latitudes have likely seen the most recent activity.

These same latitudes may also bear the scars of a shift in the moon’s spin rate. If true, this speculation may help scientists understand why Enceladus has a tortured-looking surface, with pervasive crisscrossing faults, folds and ridges. The most remarkable images show ice blocks about 10 to 100 meters (33 to 328 feet) across in a region that is unusual in its lack of the very fine-grained frost that seems to cover the rest of Enceladus.

“A landscape littered with building-sized blocks was not expected,” said Dr. Peter Thomas, an imaging-team member from Cornell University, Ithaca, N.Y. “The minimal cover of finer material and the preservation of small, crossing fracture patterns in the surrounding areas indicate that this region is young compared to the rest of Enceladus.”

False color composites of this region, created from the most recent images, show the largest exposures of coarse-grained ice fractures seen anywhere on the moon, which also supports the notion of a young surface at southern latitudes. Some of the latest images may hint at the answer. The images revealed additional examples of a distinctive “Y-shaped” tectonic feature on Enceladus. In this unusual element, parallel ridges and valleys appear to systematically fold and deform around the south polar terrains.

“These tectonic features define a boundary that isolates the young, south polar terrains from older terrains on Enceladus,” noted Dr. Paul Helfenstein, an associate of the imaging team also at Cornell University. “Their placement and orientation may tell us a very interesting story about the way the rotation of Enceladus has evolved over time and what might have provided the energy to power the geologic activity that has wracked this moon.”

The apparent absence of sizable impact craters also suggests the south pole is younger than other terrain on Enceladus. All these indications of youth are of great interest to scientists, who have long suspected Enceladus as one possible source of material for Saturn’s extensive and diffuse E ring, which coincides with the moon’s orbit. Young terrain requires a means to generate the heat needed to modify the surface. Other Cassini instrument teams are working to understand data about the temperature, composition, particles and magnetic field. Together with image interpretation, these data can create a more complete picture.

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. 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.

These Cassini images are available on the Web at: http://www.nasa.gov/cassini , http://saturn.jpl.nasa.gov and http://ciclops.org .

Original Source: NASA/JPL/SSI News Release

Posted on by Fraser Cain

SMART-1’s View of Hadley Rille

Hadley Rille on the Moon. Image credit: ESA/Space-X. Click to enlarge
This image, taken by the Advanced Moon Micro-Imager Experiment (AMIE) on board ESA?s SMART-1 spacecraft, shows the Hadley Rille on the south-east edge of Mare Imbrium on the Moon.

AMIE obtained this image from an altitude of about 2000 kilometres. It covers an area of about 100 kilometres and shows the region around Hadley Rille centred at approximately 25? North and 3? East.
The sinuous rille follows a course generally to the north-east toward the peak of Mount Hadley, after which it is named (bright feature, top right). To the east of this rille, south-west of Mount Hadley, is Mount Hadley Delta, one of the largest Appenine mountains.

The Appenine mountains mark the edge of the impact basin holding Mare Imbrium, rising between 1800 and 4500 metres above the mare. They are the bright bumps in the lower half of the image.

The valley between these two peaks is fairly well known because NASA astronauts David R. Scott and James B. Irwin landed there during the Apollo 15 mission in 1971. The landing site is near the upper right part of the rille (26.1? North and 3.9? East) on a dark mare plain called Palus Putredinis (Marsh of Decay).

The rille begins at the curved gash on the left side of this image, and is seen clearest in the rectangular, mare-floored valley in the centre of the image. It is over 120 kilometres long, and up to 1500 metres across and over 300 metres deep in places.

The rille formed nearly 3300 million years ago. In contrast, lava channels on Hawaii are usually under 10 kilometres long and are only 50-100 metres wide. The Hadley C crater next to the rille is about 5 kilometres in diameter.

Sinuous rilles are probably the most recognisable of small volcanic features on the Moon. Many partially resemble river valleys on Earth. However, the lunar rilles usually flow away from small pit structures.

The rilles mark lava channels or collapsed lava tubes that formed during mare volcanism. Indeed, the lunar samples indicate that the Moon has always been dry, thus confirming the volcanic origin of the rilles.

Still, in some cases, the lunar flows may have melted their way down into older rocks, much like rivers cut into their flood plains on Earth. Similar lava channels and tubes are found in Hawaii, but these are all much, much smaller than those found on the Moon, indication that the very low lunar gravity has a strong influence on morphological processes.

Original Source: ESA Portal

Posted on by Fraser Cain

Galaxy’s Invisible Arms Revealed

Ultra-violet image of the hidden spiral arms of NGC 4625. Image credit: NASA/JPL/Caltech. Click to enlarge
A new image from NASA’s Galaxy Evolution Explorer shows that a galaxy once thought to be rather plain and old is actually endowed with a gorgeous set of young spiral arms.

The unusual galaxy, called NGC 4625, is a remarkable find because it is relatively nearby. Until now, astronomers had thought that this kind of youthful glow in galaxies was a thing of the past.

“This galaxy is an amazing surprise,” said Dr. Armando Gil de Paz of the Carnegie Observatories, Pasadena, Calif., lead author of a paper appearing in the July issue of Astrophysical Journal Letters. “We are practically up-close and personal with a galaxy undergoing an evolutionary stage that was thought to occur only at the dawn of the universe, in very young and faraway galaxies.”

The image can be found at http://www.nasa.gov/centers/jpl/missions/galex.html or http://www.galex.caltech.edu/ . It offers astronomers their best look yet at what our Milky Way galaxy might have looked like in earlier times.

“We do not fully understand how stars were created in our galaxy,” said Dr. Barry Madore of the Carnegie Observatories, co-author of the new paper. “This nearby galaxy represents one of our possible histories, in which stars developed first in the galaxy core and then later in the arms.”

Previous visible-light images of NGC 4625 showed only an oval-shaped ball of light, with very faint hints of a halo of spiral arms. These arms were finally revealed to the ultraviolet eyes of the Galaxy Evolution Explorer. Their intense brightness indicates that the arms are teeming with hot, newborn stars, which shine primarily with ultraviolet light.

“The stars in the arms are about one billion years old, while the stars in the body are about ten times older,” said Gil de Paz.

NGC 4625’s spiral arms are very lengthy, extending four times beyond the size of the core of the galaxy. They represent the largest ultraviolet galactic disk discovered so far.

Also of interest in the new Galaxy Evolution Explorer image is a nearby companion galaxy, which looks very similar to NGC 4625, yet has no arms. How could this galactic duo have turned out so differently? Astronomers do not know, but some theories hold that the presence of the armless galaxy was required for NGC 4625 to grow a set.

“We know that interactions between galaxies can spur the creation of stars, but it is not clear why only one galaxy ended up with arms,” said Dr. Chris Martin of the California Institute of Technology in Pasadena, Calif, principal investigator for the Galaxy Evolution Explorer.

Previous studies of the gas distribution around the two galaxies indicate that NGC 4625 might have developed in a more dynamically stable environment, while the armless galaxy grew up in a more chaotic and turbulent setting.

Other authors of this paper include: Dr. S. Boissier, Carnegie Observatories; Dr. R. Swaters, University of Maryland, College Park; Dr. R. J. Tuffs, Max Planck Institut fur Kernphysik, Germany; Dr. K. Sheth, Caltech; Dr. R.C. Kennicutt, University of Arizona, Tucson; Drs. L. Bianchi and D. Thilker, Johns Hopkins University, Baltimore, Md.

Caltech leads the Galaxy Evolution Explorer mission and is responsible for science operations and data analysis. NASA’s Jet Propulsion Laboratory, Pasadena, Calif., manages the mission and built the science instrument. The mission was developed under NASA’s Explorers Program managed by the Goddard Space Flight Center, Greenbelt, Md. South Korea and France are the international partners in the mission.

For images and information about the Galaxy Evolution Explorer on the Internet, visit http://www.galex.caltech.edu/ .

Original Source: NASA News Release

Posted on by Fraser Cain

Strange Radio Emissions from Saturn

Image depicting radio emissions at Saturn. Image credit: NASA/JPL/University of Iowa. Click to enlarge
Saturn’s radio emissions could be mistaken for a Halloween sound track.

That’s how two researchers describe their recent findings, published in the July 23 issue of the Geophysical Research Letters. Their paper is based on data from the Cassini spacecraft radio and plasma wave science instrument. The study investigates sounds that are not just eerie, but also descriptive of a phenomenon similar to Earth’s northern lights.

“All of the structures we observe in Saturn’s radio spectrum are giving us clues about what might be going on in the source of the radio emissions above Saturn’s auroras,” said Dr. Bill Kurth, deputy principal investigator for the instrument. He is with the University of Iowa, Iowa City. Kurth made the discovery along with Principal Investigator Don Gurnett, a professor at the University. “We believe that the changing frequencies are related to tiny radio sources moving up and down along Saturn’s magnetic field lines.”

Samples of the resulting sounds can be heard at http://www.nasa.gov/cassini , http://saturn.jpl.nasa.gov and http://www-pw.physics.uiowa.edu/cassini/ .

The radio emissions, called Saturn kilometric radiation, are generated along with Saturn’s auroras, or northern and southern lights. Because the Cassini instrument has higher resolution compared to a similar instrument on NASA’s Voyager spacecraft, it has provided more detailed information on the spectrum and the variability of radio emissions. The high-resolution measurements allow scientists to convert the radio waves into audio recordings by shifting the frequencies down into the audio frequency range.

The terrestrial cousins of Saturn’s radio emissions were first reported in 1979 by Gurnett, who used an instrument on the International Sun-Earth Explorer spacecraft in Earth orbit. Kurth said that despite their best efforts, scientists still haven’t agreed on a theory to fully explain the phenomenon.

They will get another chance to solve the radio emission puzzle beginning in mid-2008 when Cassini will fly close to, or possibly even through, the source region at Saturn. Gurnett said, ?It is amazing that the radio emissions from Earth and Saturn sound so similar.?

Other contributors to the paper include University of Iowa scientists George Hospodarsky and Baptiste Cecconi; Mike Kaiser (currently at Goddard Space Flight Center, Greenbelt, Md.); French scientists Philippe Louarn, Philippe Zarka and Alain Lecacheux; and Austrian scientists Helmut Rucker and Mohammed Boudjada.

Cassini, carrying 12 scientific instruments, on June 30, 2004, became the first spacecraft to orbit Saturn. It is conducting a four-year study of the planet, its rings and many moons. The spacecraft carried the Huygens probe, a six-instrument European Space Agency probe that landed on Titan, Saturn’s largest moon, in January 2005.

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 Cassini-Huygens mission for NASA’s Science Mission Directorate, Washington. JPL designed, developed and assembled the Cassini orbiter. The radio and plasma wave science team is based at the University of Iowa, Iowa City.

For information on the Cassini mission visit http://saturn.jpl.nasa.gov and http://www.nasa.gov/cassini

Original Source: NASA News Release

Posted on by Fraser Cain

Why Are There Smooth Spots on Eros?

Asteroid 433 Eros taken by NEAR Shoemaker. Image credit: NASA. Click to enlarge
An asteroid’s external features, when analyzed carefully, can say a lot about its interior. So it was while he was mapping the surface of asteroid 433 Eros that Peter Thomas, a senior research associate in astronomy at Cornell University, found a simple solution to an earlier puzzle about the asteroid’s composition.

Thomas was using images collected by the Near Earth Asteroid Rendezvous mission in 2001 to create a digital map of Eros. On the asteroid’s surface, predictably pock-marked with thousands of craters accumulated from impacts over its lifetime, he saw a feature first noticed by Cornell graduate student Marc Berthoud: that a few particular patches were inexplicably smooth. That observation had led to various theories — but none that seemed completely satisfying.

In a letter appearing in the current issue of the journal Nature (Vol. 436, No. 7049, p. 366), Thomas and Northwestern University geologist Mark Robinson show that the asteroid’s smooth patches can be explained by a seismic disturbance that occurred when the crater, known as the Shoemaker crater, was formed.

The fact that seismic waves were carried through the center of the asteroid shows that the asteroid’s core is cohesive enough to transmit such waves, Thomas says. And the smoothing-out effect within a radius of up to 9 kilometers from the 7.6-kilometer Shoemaker crater — even on the opposite side of the asteroid — indicates that Eros’ surface is loose enough to get shaken down by the impact.

Asteroids are small, planetlike bodies that date back to the beginning of the solar system, so studying them can give astronomers insight into the solar system’s formation. And while no asteroids currently threaten Earth, knowing more about their composition could help prepare for a possible future encounter.

Eros, whose surface is a jumble of house-sized boulders and small stones (“what geologists call ‘poorly sorted,'” says Thomas), is the most carefully studied asteroid, in part because its orbit brings it close to earth.

Thomas and Robinson considered various theories for the regions of smoothness, including the idea that ejecta from another impact had blanketed the areas. But they rejected the ejecta hypothesis when calculations showed an impact Shoemaker’s size wouldn’t create enough material to cover the surface indicated. And even if it did, they add, the asteroid’s irregular shape and motion would cause the ejecta to be distributed differently.

In contrast, says Thomas, the shaking-down hypothesis fits the evidence neatly. “The classic light bulb goes on in your head,” he says; the crater density of small craters increases with the distance from the Shoemaker crater. “Simple geometry says something like a simple seismic wave.”

The NEAR mission, in which a NASA spacecraft landed on the asteroid’s surface in 2001 after orbiting it for a year, yielded more than 100,000 images of the small asteroid. (Eros is about 33 kilometers long, 13 kilometers wide and 8 kilometers thick). Since the mission’s conclusion 16 days after the landing, scientists from institutions around the world have been sorting through the data.

That process is expected to continue for years. “Careful mapping of things on the surface can give you a good clue as to what’s inside,” says Thomas. “And in one sense, we’ve barely begun.”

Original Source: Cornell University News Release

Posted on by Fraser Cain

What’s Up This Week – July 25 – July 31, 2005

M107. Image credit: NOAO/AURA/NSF. Click to enlarge.
Monday, July 25 – With the later rise of the Moon this week, we’ll have the opportunity to do some study of globular clusters. Let’s start with one that is often overlooked – M107. Discovered by Pierre Mechain in 1782, and added to the catalog in 1947, it’s probably one of the latest of the Messier objects to be discovered and wasn’t resolved into individual stars until studied by Herschel in 1793.

Located about one quarter the distance between Zeta Ophiuchius and Beta Scorpius, the M107 isn’t the most impressive of globulars, but it is surprisingly bright in a small telescope. It’s a curious cluster, for some believe it contains dark, dust obscured areas which makes it unusual. Located around 21,000 light years away, this little beauty contains around 25 known variable stars. Visually, the cluster begins to resolve around the edges to mid-aperture and the structure is rather loose. If sky conditions permit, the resolution of individual chains at the globular’s edges make this globular well worth a visit.

Tuesday, July 26 – Tonight let’s continue on our journey through the galactic halo and pick up the M9 located around 3 and a half degrees east of Eta Ophiuchus. Discovered by Messier in 1764, this particular globular cluster is one of the nearest to our galactic center, and is around 2,600 light years away from our solar system. Now let’s notice differences – check out the contrast between this small globular’s appearance as compared to last night’s M107. At this point we’re seeing not only a strong central concentration, but a slight oval shape. This change in structure is caused by the strong absorption of star light by dust along its northwest edge. Of its huge stellar population, only a dozen or so variable stars are known in M9, which is rather few for a cluster of its size. Visually, it appears more compact and slightly oblate. Rather than chains of stars resolving at the edges, the M9 appears to have larger, individual stars in a random pattern.

For those with larger scopes, you also have the opportunity to study two more that are nearby – NGC 6356 about a degree to the northeast and NGC 6342 to the southeast. You will find the NGC 6356 to be rather small – but bright. The NGC 6342 appears to be even smaller and far less distinct. Compare them both to the structure of the M9 and you will find the 6356 to be the most concentrated of the three.

Wednesday, July 27 – This morning the Moon dances with Mars. Luna will appear about half a fist width to the northwest (upper right) of the Red Planet just before dawn.

Tonight we’re going monster hunting, and heading about a fist’s width north of Beta Librae towards a previous study – double star 5 Serpens and the glorious M5. First discovered by Kirch in 1702, re-discovered by Messier in 1764, and resolved by in 1791 by Herschel, this fifth brightest globular cluster in the sky is considered to be one of the most ancient and may be as many as 13 billion years old.

Further away from the dusty galactic center, resolution explodes as the viewer moves up in aperture. Easily seen as roundish ball of unresolved stars in binoculars, even small scopes will begin to pick individual stellar points out of this mass and begin to realize that the M5 is not perfectly round. Its brighter stars are also distributed randomly and it contains an unusually large number of variables. Note its structure. While it is far more grand than the others we have observed, it is far less concentrated at the core.

Thursday, July 28 – This morning the Moon has waltzed to the other side of Mar’s position, putting it about a fist width to the planet’s northwest. Notice that Mars continues to brighten and will soon have reached -1 magnitude as it moves toward the Sun. Today in 1851, the first photograph of the Sun was made during a total eclipse revealing the corona for the first time.

Tonight we will hustle off to explore a single small globular – M80. Located about 4 degrees northwest of Antares (half a fist), this little globular cluster is a powerpunch. Located in a region heavily obscured by dark dust, the M80 will shine like an unresolvable star to small binoculars and reveal itself to be one of the most heavily concentrated globulars to the telescope. Discovered within days of each other by Messier and Mechain respectively in 1781, this intense cluster is around 36,000 light years distant.

In 1860, the M80 became the first globular cluster to contain a nova. As stunned scientists watched, a centrally located star brightened to magnitude 7 over a period of days and became known as T Scorpii. The event then dimmed more rapidly than expected, making observers wonder exactly what they had seen. Since most globular clusters contain stars all of relatively the same age, the hypothesis was put forward that perhaps they had witnessed an actual collision of stellar members. Given the cluster contains more than a million stars, the probability remains that some 2700 collisions of this type may have occurred during the M80’s lifetime.

Now grab a comfortable seat because the Delta Aquarid meteor shower reaches its peak tonight. It is not considered a prolific shower, and the average fall rate is about 25 per hour – but who wouldn’t want to take a chance on observing a meteor about every 4 to 5 minutes? These travellers are considered to be quite slow, with speeds around 24 kilometers per second and are known to leave yellow trails. One of the most endearing qualities of this annual shower is its broad stream of around 20 days before and 20 days after peak. This will allow it to continue for at least another week and overlap the beginning stages of the famous Perseids.

The Delta Aquarid stream is a complicated one, and a mystery not quite yet solved. It is possible that gravitation split the stream from a single comet into two parts, and each may very well be a separate stream. One thing we know for certain is they will seem to eminate from the area around Capricornus and Aquarius, so you will have best luck facing southeast and getting away from city lights. On a personal note, I have observed high activity from the region for the last two weeks, which means we may be passing through a more heavily concentrated portion of the stream. While I cannot guarantee you’ll see significant activity, I highly urge you to enjoy a warm summer night and take a chance at “catching a shooting star”.

Friday, July 29 – The weekend has arrived at last, and if you have not had the chance to observe the earlier globular clusters, pick them up tonight and let’s head on out towards two more giants that appear differently from the rest (and each other) – previous study M10 and M12.

Located about half a fist width west of Beta Ophiuchus, the M12 is the northern most of this pair. Easily seen as a hazy round spot in binoculars, let’s find out what makes it tick. Since this large globular is much more loosely concentrated, smaller scopes will begin to resolve individual stars from this 24,000 light year distant cluster. Note there is a slight concentration toward the core region, but for the most part the cluster appears fairly even. Large instruments will resolve out individual chains and knots of stars.

Now let’s drop about 3 and half degrees southeast and check out M10. What a difference in structure! Although they seem to be close together and close in size, the pair are actually separated by some 2,000 light years. The M10 is a much more concentrated globular showing a brighter core region to even the most modest of instruments. This compression of stars is what classifies one type of globular cluster from another and M10 appears brighter, not because of this compression, but because it is about 2,000 light years closer.

Saturday, July 30 – Before sunrise this morning look for the waning crescent Moon as it travels along the returning constellation of Taurus. Aldebaran, the “eye of the bull” will appear about a fist width below Selene. The Pleiades will complete the scene as it appears about half a fist width to the Moon’s upper right. Take out your binoculars to take a peek at the “Seven Sisters”.

For central through western Australia and toward Indonesia, viewers will have the opportunity to see the Moon occult the Pleiades. This is an event you won’t want to miss, so please check this IOTA webpage to get precise times in your location. Clear skies!

For hard core observers, tonight’s globular cluster study will require at least a mid-aperture telescope, because we’re going after a same field pair – NGC 6522 and NGC 6528. You will find them easily at low power just a breath northwest of Gamma Sagittarius, better known as Al Nasl – or the tip of the “teapot’s” spout. Once located, switch to higher power to keep Gamma out of the field and let’s check them out.

The brighter, and slightly larger, of the pair to the northeast is NGC 6522. Note its level of concentration and compared to NGC 6528. Both are located around 2,000 light years away from the galactic center and seen through a very special area of the sky known as “Baade’s Window” – one of the few areas towards our galaxy’s core region not obscured by dark dust. While each are similar in concentration, distance, etc., the NGC 6522 has a slight amount of resolution towards its edges while the 6528 appears more random.

Now, relax and enjoy the peak of the Capricornid meteor shower! Although it is hard for the casual observer to distinguish these meteors from the Delta Aquarids, no one minds. Again, face the general direction of southeast and enjoy! The fall rate for this shower is around 10 to 35 per hour, but unlike the Aquarids, this stream produces those great “fireballs” known as bolides. Enjoy…

Sunday, July 31 – For viewers in eastern and central Australia and all of New Zealand, you will have the opportunity to see the Moon occult Beta Tauri this morning. Please check this IOTA webpage for times and locations in your area.

Tonight we’re going to move back toward Ophiuchus and a globular cluster unlike any that we’ve seen so far – M19. Locate Antares and about a fist width to the east you will see Theta Ophiucus with fainter star 44 to its northwest and multiple system 36 to the southeast. Move around 2 degrees to the west of 36 and let’s check it out.

With a visual magnitude of 6.8, this class VIII globular cluster can be seen with small binoculars, but requires a telescope to begin to take on form. Discovered by Charles Messier in 1764, the M19 is the most oblate globular known. Harlow Shapely, who studied globular clusters and cataloged their elliptical natures, estimated about twice as many stars along the major axis as along the minor. This stretching of the cluster from its accepted round shape may very well have to do with its proximity to the Galactic Center – a distance of only about 5,200 light years. This makes it only a tiny bit more remote from us than the very center of the Milky Way!

Very rich and dense, even smaller telescopes can pick up that this globular cluster has a faint blue tinge to it. It is definately one of the more interesting, due to its shape, but for the adventurous? There’s two more. The NGC 6293 is about a degree and a half to the east/southeast and is far brighter than you might expect. Note how much more round and concentrated directly at the core this companion is. Now move about a degree and a half to the north/northeast of M19 to find dimmer NGC 6284. Although it is the same size as the 6293, look at how much more “loose” this one is constructed!

Our globular cluster studies will continue next week, so stick around! In the mean time? May all your journeys be at Light Speed… ~Tammy Plotner