NEXT MEETING 7:30 p.m., Monday, November 3, 2014
Transcription
NEXT MEETING 7:30 p.m., Monday, November 3, 2014
Volume 51 No. 11 November 1, 2014 NEXT MEETING 7:30 p.m., Monday, November 3, 2014 Maturango Museum, 100 East Las Flores Avenue, Ridgecrest, California. PROGRAM FOR THE November 3rd, MEETING – We will be seeing a presentation of a video I have acquired. This will be a recorded talk on the “Kepler Mission”. We will have an update on access to the CLAS public outreach site. It’s also time to put in our order for 2015 Calendars and RASC Handbooks. DATES TO KEEP IN MIND Sunday, Nov. 02: Daylight Saving Time ENDS – set clocks BACK 1 Hour. Monday, Nov. 03: Regular CLAS Meeting at the Maturango Museum in Ridgecrest, 7:30 p.m. Friday, Nov. 21: Brown Road star party. Signs out at 6:00 p.m.- viewing at 6:30 p.m. (New Moon - 1) Sat., Nov. 22: Red Rock Canyon – Visitors Center, Star viewing 30 min. after Sundown. Tuesday, Nov. 23: Deadline for next Skywatchers Newsletter. Monday, Dec. 01: Regular CLAS Meeting at the Maturango Museum in Ridgecrest, 7:30 p.m. STAR PARTY SCHEDULE FOR THE 2014 SEASON: Star Parties will be held on the dates listed below. Star Parties are an activity where members and guests come together to view the skies. If you have a telescope, bring it; if not, come and look through someone else’s. They are held at a site in the open desert south of Ridgecrest. To reach the site from Ridgecrest, go south on China Lake Boulevard 6.5 miles from its intersection with Ridgecrest Boulevard. Continue straight across Highway 395 and you will be on Brown Road (Old Highway 395). Follow Brown Road as it curves to the right and goes west. After 2.3 miles, there will be a 30-inch orange cone on the left. Turn left and follow the dirt road marked by 12-inch cones. The CLAS star party is 0.5 miles along this road. Signs and cones will be put out about a half hour before viewing starts. Call Roger Brower 760-375-1181 or Bruce Churchill 760-677-1143, for more information. Friday, Nov. 21: Brown Road star party. Signs out at 6:00 p.m.- viewing at 6:30 p.m. (New Moon - 1) Saturday Nov 22 Red Rock Canyon – Visitors Center, Star viewing 30 min. after Sundown. Above are the latest scheduled Star Parties for the 2014 season. If something else comes up watch your email. This ends our public star party season for 2014. We will resume these events in March 2015. Some public star parties are held at the Maturango Museum “Carroll L. Evans, Jr. Observatory Dome” on the Thursday evening proceeding some Brown Road Friday Star Parties. Exact dates will be announced by email. Rosetta – Philae landing time: First signal from the comet surface Rosetta will deploy the Philae lander on November 11 at 11:35 PM PST. Confirmation of the landing will arrive at ground stations around 8:03 AM PST. Link with countdown clock: http://rosetta.jpl.nasa.gov/ Editors note: Check the NASA Channel for possible coverage ! Video link: http://rosetta.jpl.nasa.gov/news/rosetta%E2%80%99s-journey-pre-delivery-orbit-begins Rosetta Comet Fires Its Jets Credits: ESA/Rosetta/NAVCAM At a distance of 7.8 km from the surface, the image scale is about 66.5 cm/pixel, so each 1024 x 1024 pixel frame is about 680 m across (although if we assume the furthest point away is an additional ~1 km further from the centre, the image scale is about 92 cm/pixel). The combined effect of the comet rotating between the first and last images taken in the sequence and the spacecraft moving in the same time is particularly apparent if you try to match features in the lower left and lower right images, which are the first and last images in the 20-minute sequence, respectively. You may notice a number of bright streaks. Some of these will likely be dust grains ejected from the comet, captured in the six-second exposure time of the images. Link: http://www.jpl.nasa.gov/news/news.php?feature=4319 Extra stuff: 3 – D Photo & BLOG (for kids large and small): http://blogs.esa.int/rosetta/2014/08/14/comet-67pc-g-in-3d/ For Kids–Video: http://www.esa.int/spaceinvideos/Videos/2014/07/RosettaAreWeThereYet_Fabulous_fables_and_tales_of_tails First Resolved Image of a Long-Period Comet's Nucleus Link: http://www.jpl.nasa.gov/spaceimages/details.php?id=pia18618 These images were taken of comet C/2013 A1 Siding Spring by NASA's Mars Reconnaissance Orbiter on Oct. 19, 2014, during the comet's close flyby of Mars and the spacecraft. Comet Siding Spring is on its first trip this close to the sun from the Oort Cloud at the outer fringe of the solar system. This is the first resolved imaging of the nucleus of a long-period comet. The High Resolution Imaging Science Experiment (HiRISE) camera on Mars Reconnaissance Orbiter acquired images of this comet from a minimum distance of about 86,000 miles (138,000 kilometers), yielding a scale of about 150 yards (138 meters) per pixel. Telescopic observers had modeled the size of the nucleus as about half a mile, or one kilometer, wide. However, the best HiRISE images show only two to three pixels across the brightest feature, probably the nucleus, suggesting a size less than half that estimate. This composite image shows two versions of each of two of the best HiRISE images of the comet. Shown at top are images with the full dynamic range, showing the nucleus and bright coma near the nucleus. Shown at bottom are versions where the fainter outer coma is brightened, saturating the inner region. The images at left and right were taken about nine minutes apart. These closest-approach images were made possible due to very precise pointing and slewing of the Mars Reconnaissance Orbiter by engineers at Lockheed Martin in Denver, based on comet position calculations by engineers at NASA's Jet Propulsion Laboratory, Pasadena, California. HiRISE acquired three images 12 days before closest approach, when the comet was barely detectable above the "noise level" of the images. These early images indicated the comet was not quite at its predicted location. This new viewing angle on the comet was used to update its predicted location and timing at closest approach. Without this update, the comet may have been outside the HiRISE image area in the best images. For more information on these images and future updates, see http://hirise.lpl.arizona.edu/. HiRISE is one of six instruments on NASA's Mars Reconnaissance Orbiter. The University of Arizona, Tucson, operates HiRISE, which was built by Ball Aerospace & Technologies Corp., Boulder, Colorado. Link: http://www.jpl.nasa.gov/news/news.php?feature=4349 For more information about comet Siding Spring, see http://mars.nasa.gov/comets/sidingspring/ NASA GRAIL Mission Points to Origin of 'Ocean of Storms' on Earth's Moon Using data from NASA's Gravity Recovery and Interior Laboratory (GRAIL), mission scientists have solved a lunar mystery almost as old as the moon itself. Early theories suggested the craggy outline of a region of the moon's surface known as Oceanus Procellarum, or the Ocean of Storms, was caused by an asteroid impact. If this theory had been correct, the basin it formed would be the largest asteroid impact basin on the moon. However, mission scientists studying GRAIL data believe they have found evidence the craggy outline of this rectangular region -- roughly 1,600 miles (2,600 kilometers) across -- is actually the result of the formation of ancient rift valleys. "The near side of the moon has been studied for centuries, and yet continues to offer up surprises for scientists with the right tools," said Maria Zuber, principal investigator of NASA's GRAIL mission, from the Massachusetts Institute of Technology, Cambridge. "We interpret the gravity anomalies discovered by GRAIL as part of the lunar magma plumbing system -- the conduits that fed lava to the surface during ancient volcanic eruptions." The surface of the moon's near side is dominated by a unique area called the Procellarum region, characterized by low elevations, unique composition and numerous ancient volcanic plains. The rifts are buried beneath dark volcanic plains on the near side of the moon and have been detected only in the gravity data provided by GRAIL. The lava-flooded rift valleys are unlike anything found anywhere else on the moon and may at one time have resembled rift zones on Earth, Mars and Venus. The findings are published online in the journal Nature. Another theory arising from recent data analysis suggests this region formed as a result of churning deep in the interior of the moon that led to a high concentration of heat- producing radioactive elements in the crust and mantle of this region. Scientists studied the gradients in gravity data from GRAIL, which revealed a rectangular shape in resulting gravitational anomalies. "The rectangular pattern of gravity anomalies was completely unexpected," said Jeff Andrews-Hanna, a GRAIL co-investigator at the Colorado School of Mines in Golden, and lead author of the paper. "Using the gradients in the gravity data to reveal the rectangular pattern of anomalies, we can now clearly and completely see structures that were only hinted at by surface observations." The rectangular pattern, with its angular corners and straight sides, contradicts the theory that Procellarum is an ancient impact basin, since such an impact would create a circular basin. Instead, the new research suggests processes beneath the moon's surface dominated the evolution of this region. Over time, the region would cool and contract, pulling away from its surroundings and creating fractures similar to the cracks that form in mud as it dries out, but on a much larger scale. The study also noted a surprising similarity between the rectangular pattern of structures on the moon, and those surrounding the south polar region of Saturn's icy moon Enceladus. Both patterns appear to be related to volcanic and tectonic processes operating on their respective worlds. Topography of Earth's moon generated from data collected by the Lunar Orbiter Laser Altimeter with the gravity anomalies bordering the Procellarum region superimposed in blue. The border structures are shown using calculated gravity gradients These gravity anomalies are interpreted as ancient lava-flooded rift zones buried beneath the volcanic plains (or maria) on the nearside of the Moon Image credit: NASA/Colorado School of Mines/MIT/GSFC/Scientific Visualization Studio "Our gravity data are opening up a new chapter of lunar history, during which the moon was a more dynamic place than suggested by the cratered landscape that is visible to the naked eye," said Andrews-Hanna. "More work is needed to understand the cause of this newfound pattern of gravity anomalies, and the implications for the history of the moon." Launched as GRAIL A and GRAIL B in September 2011, the probes, renamed Ebb and Flow, operated in a nearly circular orbit near the poles of the moon at an altitude of about 34 miles (55 kilometers) until their mission ended in December 2012. The distance between the twin probes changed slightly as they flew over areas of greater and lesser gravity caused by visible features, such as mountains and craters, and by masses hidden beneath the lunar surface. A view of Earth's moon looking south across Oceanus Procellarum, representing how the western border structures may have looked while active. Image credit: NASA/Colorado School of Mines/MIT/JPL/GSFC. The twin spacecraft flew in a nearly circular orbit until the end of the mission on Dec. 17, 2012, when the probes intentionally were sent into the moon's surface. NASA later named the impact site in honor of late astronaut Sally K. Ride, who was America's first woman in space and a member of the GRAIL mission team. GRAIL's prime and extended science missions generated the highest-resolution gravity field map of any celestial body. The map will provide a better understanding of how Earth and other rocky planets in the solar system formed and evolved. Link: http://www.jpl.nasa.gov/news/news.php?release=2014-333\ Saturn Moon MIMAS May Hide a 'Fossil' Core or an Ocean A new study focused on the interior of Saturn's icy moon Mimas suggests its cratered surface hides one of two intriguing possibilities: Either the moon's frozen core is shaped something like a football, or the satellite contains a liquid water ocean. Researchers used numerous images of Mimas taken by NASA's Cassini mission to determine how much the moon wobbles as it orbits Saturn. They then evaluated several possible models for how its interior might be arranged, finding two possibilities that fit their data. "The data suggest that something is not right, so to speak, inside Mimas," said Radwan Tajeddine, a Cassini research associate at Cornell University, Ithaca, New York, and lead author on the paper. "The amount of wobble we measured is double what was predicted." Either possiblity for the interior of Mimas would be interesting, according to Tajeddine, as the moon's heavily cratered outward appearance does not suggest anything unusual lies beneath its surface. Because Mimas formed more than four billion years ago, scientists would expect its core to have relaxed into a more or less spherical shape by now. So if Mimas' core is oblong in shape, it likely represents a record of the moon's formation, frozen in time. If Mimas possesses an ocean, it would join an exclusive club of "ocean worlds" that includes several moons of Jupiter and two other Saturn moons, Enceladus and Titan. A global ocean would be surprising, said Tajeddine, as the surface of Mimas does not display signs of geologic activity. Like a lot of moons in the solar system, including our own, Mimas always shows essentially the same face to its parent planet. This is called a spin-orbit resonance, meaning the moon's rotation, or spin, is in sync with its orbit around Saturn. Like Earth's moon, Mimas takes the same amount of time to spin completely around on its axis as it takes to orbit its planet. The orbit of Mimas is very slightly stretched out, forming an ellipse rather than a perfect circle. This slight deviation causes the point on Mimas' surface that faces Saturn tovary a bit over the course of an orbit -an observer on Saturn would see Mimas wobble slightly during its orbit, causing small amounts of terrain over the limb to become visible. This effect is called libration, and Earth's moon does it as well. "Observing libration can provide useful insights about what is going on inside a body," said Tajeddine. "In this case, it is telling us that this cratered little moon may be more complex than we thought." Models developed by Tajeddine and co-authors from France and Belgium indicate that, if Mimas is hiding a liquid water ocean, it lies 15 to 20 miles (24 to 31 kilometers) beneath the moon's impact-battered surface. At 246 miles (396 kilometers) wide, Mimas is too small to have retained internal heat from its formation, so some other source of energy would be required to maintain an underground ocean. The researchers note that there is evidence that Mimas' current, elongated orbit could have been even more stretched out in the past, which might have created enough tidal heating to produce an ocean. Although an ocean within Mimas would be a surprise, the authors found that the interior model they considered for an oblong core ought to give the moon a slightly different shape than what is observed. They suggest that other models could be developed to explain the moon's observed libration, and that further measurements by Cassini could help determine which model is most likely to be correct. The study is published in the Oct. 17 issue of the journal Science. Link: http://www.jpl.nasa.gov/news/news.php?feature=4342 How Far, the Stars? Quasars Solve 'Seven Sisters' Star Cluster Mystery Super-bright galaxies powered by black holes have helped astronomers come up with the most accurate distance yet to the iconic Pleiades star cluster The measurement, which used quasars as bright and consistent relative-distance markers, charted the famous "Seven Sisters" star cluster at 136.2 parsecs, or 444 light-years, away from Earth. Lead researcher Carl Melis first took on the project five years ago while still in graduate school at the University of California, Los Angeles, after meeting with John Stauffer (a co-author on the paper). Melis recalled being astounded to learn there was a dispute over how far away the Pleiades are from Earth Here’s this canonical cluster — everyone knows the Pleiades, even the layperson — and we don’t even know how far away it is,” Melis, who is now an astrophysicist at the University of California, San Diego, told Space.com. Visual vs. radio measurements When astronomers estimate stellar distances for objects that are relatively close to Earth, they use a method called parallax. Simply speaking, measurements of a star’s position relative to other stars are taken when Earth is at either side of its yearlong orbit. By measuring the change in position, astronomers can estimate the distance by simple geometry. Scientists have known of this technique since the 1800s, but it has limitations. The biggest one is that other stars also move, which makes it difficult to come up with precise measurements. So, instead of relying on this method, Melis’ team used radio measurements to perform the work, which opened up a more reliable distance beacon: quasars, amazingly bright galactic cores powered by supermassive black holes. Quasars, which shine clearly in the spectrum of radio waves, are extremely far away — so far away that their relative motion hasn’t yet been measured, Melis said. “The beauty of this technique, as I watch my star and make measurements, is any change is entirely due to my star. The quasar just sits there. That’s the difference between optical and radio techniques,” Melis said. The researchers used the Very Long Baseline Array, a network of 10 telescopes spread thousands of miles apart here on Earth, and several other radio dishes to perform the measurements. For two years, once a week, a distance measurement was taken of four Pleiades star systems, and five stars. Along the way, researchers made a discovery: Two of those stars are a binary system, something that was suspected but had not been verified. Measurements made at the Keck Observatory in Hawaii confirmed the binary, Melis said. Resolving a controversy? Melis said his team’s work resolves a decades-long controversy concerning just how far away the Pleiades are. Conventional parallax pegged the distance at 133.5 parsecs, or 435 light-years, while Europe’s Hipparcos satellite returned a result of 120.2 parsecs (392 light-years). Hipparcos still measured stars relative to other stars, but the sheer number of stars it used far eclipsed other measurements, Melis said. The satellite modeled the movements of about 120,000 stars, and in most cases, is considered highly accurate. Other measurements tend to use only up to 1,000 stars, he said. “Hipparcos has been a huge success and revolutionized our understanding of stellar astrophysics, but apparently something went wrong [with this measurement], which is unfortunate,” Melis said. While he acknowledged other researchers may have their own ideas about his team’s accuracy, Melis said the radio technique has been used before. Different astrophysicists have employed the method for measurements to objects such as the Orion Nebula cluster, the Taurus star-forming region and high-mass starforming regions throughout the Milky Way. Melis added that four more star distance measurements for the Pleiades will be incorporated into another research paper he is working on, planned for later this year. In some cases, astronomers have managed to track orbital motion of the stars, which could yield more-accurate mass measurements of the stars themselves, he added. Link: http://news.yahoo.com/far-stars-quasars-solve-seven-sisters-star-cluster-111405959.html Just in – stop the presses !! The scent of a comet: Rotten eggs and pee (from Don Goodson) Eau de Comet isn't, we now know, the most seductive scent floating around in our galaxy. The Rosetta probe's Rosetta Orbiter Sensor for Ion and Neutral Analysis (ROSINA) has been using its two mass spectrometers to detect the "smell" of 67P/Churyumov-Gerasimenko. From its position in orbit around the comet, ROSINA was able to detect the chemical makeup of 67P/CG's coma -- the halo of material surrounding the comet, which increases in intensity as the comet nears the sun and heats up, causing parts of it to sublimate. At 400 million kilometres (250 million miles) from the sun, the Rosetta team thought the coma would only contain the comet's most volatile molecules -- carbon dioxide and carbon monoxide -- but it is much richer than previously thought. As of September 11, the ROSINA team knew that the coma contained (in gas form) water, carbon monoxide, carbon dioxide, ammonia, methane and methanol. The new measurements have detected the presence of formaldehyde, hydrogen sulphide, hydrogen cyanide, sulphur dioxide and carbon disulphide -- albeit in relatively low density.This heady melange -- aside from being quit toxic to humans -- would smell quite vile. "The perfume of 67P/C-G is quite strong, with the odour of rotten eggs (hydrogen sulphide), horse stable (ammonia), and the pungent, suffocating odour of formaldehyde. This is mixed with the faint, bitter, almond-like aroma of hydrogen cyanide," said ROSINA principal investigator Kathrin Altwegg. "Add some whiff of alcohol (methanol) to this mixture, paired with the vinegar-like aroma of sulphur dioxide and a hint of the sweet aromatic scent of carbon disulphide, and you arrive at the 'perfume' of our comet." As 67P/C-G draws closer to the sun, it's expected that it will begin releasing more molecules. These -and the changes in the comet's coma -- will allow the scientists to determine the composition of the comet itself. This, in turn, will allow comparison with other comets -- such as Siding Spring, which recently flew past Mars. The 67P/C-G hails from the Kuiper Belt, within our solar system, and Siding Spring is from the Oort Cloud -- over 1,000 times further away from the sun than the Kuiper Belt. Comparing the two comets could help determine the composition of the nebula that gave birth to the sun and solar system. Editor: What might Pluto smell like ?? For more information about Rosetta, visit http://rosetta.jpl.nasa.gov/. Leonids Peak night Nov 17-18 2014 Active from November 5th to 30th 2014 Parent Object: 55P/Tempel-Tuttle The Leonids are best known for producing great meteor storms in the years of 1833, 1866, 1966, and 2001. These outbursts of meteor activity are best seen when the parent object, comet 55P/Tempel-Tuttle, is near perihelion (closest approach to the sun). Yet it is not the fresh material we see from the comet, but rather debris from earlier returns that also happen to be most dense at the same time. Unfortunately it appears that the earth will not encounter any dense clouds of debris until 2099. Therefore when the comet returns in 2031 and 2064, there will be no meteor storms, but perhaps several good displays of Leonid activity when rates are in excess of 100 per hour. The best we can hope for now until the year 2030 is peaks of around 15 shower members per hour and perhaps an occasional weak outburst when the earth passes near a debris trail. The Leonids are often bright meteors with a high percentage of persistent trains. Radiant: 10:08 +21.6° - ZHR: 15 - Velocity: 44 miles/sec (swift - 71km/sec) Adapted from American Meteor Soc. Masilov in Russia Predicts: A single background maximum is expected for Leonids in 2014. According to the IMO data, it occurs on the solar longitude 235.27°, in 2014 it corresponds to 22:02 UT (14:02 PST) 17 November. As observations show, in "usual" years its maximum ZHR is around 15-20. No other notable activity peaks were found. Far from background maximum, within 11-15 UT (0300-0700 PST) on 21 November a small amount of meteors can be produced by very rarified 1567 trail, however this addition should be very small (ZHRex=1 from 1567 trail, ZHRex=2-3 from 1567 trail plus background activity) Keep up with the “Curiosity” Mars Mission http://www.nasa.gov/mission_pages/msl/index.html THE SKY IN NOVEMBER by Roger Brower Venus is to close to the sun to be easily viewed this month. Jupiter moves to the evening sky this month. It rises about midnight on the first and 10PM on the 30th. Look for it in the east after it rises. Mercury remains in the morning sky early this month but will be gone by midmonth. Look for it in the east before the sun rises. Saturn is to close to the Sun to be easily visible this month. Mars is in Sagittarius this month. Look for it in the southwest after sunset. The Leonid meteor shower peaks on the mornings of November 17th and 18th. 2015 ROYAL ASTRONOMICAL SOCIETY HANDBOOKS AND CALENDARS The group rate price for a single copy if you buy in person from CLAS is $25.00 for the handbook and $15.00 for the calendar. Calendar and Handbook are sold together for the combined price of $35.00. We will be ordering soon so if you want copies contact Roger (email-below) or order at the Nov. meeting. MEMBERSHIP INFORMATION Basic CLAS dues are $25.00 per year - due in January. Students and Skywatchers Newsletter are FREE. Members also receive discounted rates for Astronomy Magazine and/or Sky and Telescope Magazine. The fee schedule is as follows: Basic membership $25.00 per year. Membership with Astronomy magazine is $59.00 per year. Membership with Sky and Telescope magazine is $58.00 per year. Membership with both S & T and Astronomy is $92.00 per year. Send your check to: Roger Brower, Treasurer, China Lake Astronomical Society, P.O. Box 1783, Ridgecrest, CA 93556. PRESIDENT – Earl Wilson – NO PHONE (email [email protected]) VICE-PRESIDENT – Bruce Churchill - 760-677-1143 (email [email protected]) SECRETARY – Ted Hodgkinson - 661-754-0561 (email [email protected]) TREASURER – Roger Brower - 760-375-1181 (email [email protected]) NEWSLETTER EDITOR – Earl Wilson – NO PHONE (email [email protected]) WESTERN AMATEUR ASTRONOMERS WEB SITE http://www.waa.av.org/ Meetings of the China Lake Astronomical Society are held at the Maturango Museum at 7:30 p.m. on the first Monday evening of each month, except when the first Monday is a holiday. CLAS WEB PAGE http://www.chinalakeastrosoc.org ARCHIVE OF CLAS NEWSLETTERS http://www.ridgenet.net/~clevans/clas/