Volume XX No. 4 December 2008 What's Inside… Welcome New Members Pg 3 Faustini Crater Pg 4 Stewart's Skybox Pg 6 PowerPoint Class Pg 13 General Meeting Pg 14 Contacts Pg 15 Theater in the Sky Pg 16 NASA Science Update Pg 17 Astro Outreach Pg 19 Note: Use bookmark panel in Adobe Reader. "Do You Have A Match?" By Clif Ashcraft and Ray Shapp Digital Video Finder for Sperry's 24-Inch Telescope The image on the left was produced in real time by a digital video camera aligned with the main optical tube of the 24-inch reflector at Sperry Observatory. The image on the right is a sky chart drawn by the Guide 8 planetarium computer program. Notice that both fields of view are about 3° high by 4° wide, which is about the same field size as that seen in ordinary binoculars. Qualified Observers can now place any desired object into the center of a high-powered eyepiece merely by moving the big telescope until the two star patterns match. The only requirements are that the target object is above the horizon, the sky is clear, and the dome is open. It is also necessary to remove the dust covers. In actual practice, the procedure is only a little more involved. A single computer displays the video camera output on a flat panel monitor, and it simultaneously displays the Guide sky chart on a separate CRT monitor. The operators insure that Guide is using a customized configuration that loads the latitude and longitude of the observatory and the current date and time. The desired target is selected from Guide's extensive database of stars, planets, comets, asteroids, galaxies, nebulae, and clusters, and it is drawn on the screen. A legend continuously displays the Local Sidereal Time (LST), and the Right Ascension and Declination of the target object. Operators adjust an hour circle on the R.A. axis of the telescope to agree with the current LST. They then physically move the main telescope until it is aligned with the target's approximate R.A. and Declination using the setting circles that have always been on the telescope. The smallest index marks on the R.A. circle are in five-minute increments, and the Declination circle is graduated in full degrees. Those crude scales are never fine enough to locate a target in the main eyepiece, therefore, it has always been necessary to crane our necks, and hunt for the target using a low-power finder 'scope and/or a Telrad. But now, using the relatively large field of the video camera, the target will appear somewhere on the screen. Operators can then move the target to the center of the flat panel monitor by slewing the telescope using the hand paddle. It takes no training at all to recognize when the star patterns on the two computer monitors match. It does require a little practice to learn which direction on the hand paddle moves the camera to match the sky chart. How Many Objects Can You Show on a Public Night? After our observer teams gain a little experience with the video finder system, it should be a routine task to switch from object to object. During the transitions between objects, the Public can be engaged in the process by watching the two monitors and "helping" with spotting the match. The total number of targets acquired and displayed during a given session will depend on how much time it takes to satisfy the line of "customers" on each target. The transitions should take only a few minutes. Video and CCD Imaging Outside of public hours, when only AAI members and their guests are present, the digital camera can be used in two kinds of imaging. For relatively bright or extended objects, a series of video sequences can be captured and processed offline using the RegiStax software program to produce good quality still images. In this mode, it wouldn't even be necessary to insert any eyepiece into the telescope. For dim compact objects, the digital finder can be used to center the target in the very tiny field of view of the club's ST-8 CCD camera which would be mounted in the telescope's eyepiece holder. The CCD camera's supporting software would be used to capture CCD frames which would be processed offline. For a good example of the kind of still images that can be produced by this kind of video camera, see "Faustini Crater Image Used By LCROSS Astrono-mers" on page 4. Details For those of you who are interested in the specifics of what we bought and installed on the telescope, here are the details: The camera itself is a DMK21AU04 industrial strength webcam purchased from The Imaging Source ( see http://www.theimagingsource.com/en/products/ ). It has a 640x480 Kodak CCD detector with 5.7 micron pixels. The camera is monochrome, i.e., there is no Bayer color filter matrix over the CCD, so if we want to take color images with it, we would have to use color filters, and take separate red, green, and blue images, and combine them to get color. The added sensitivity we get by not having the Bayer filter matrix in the way is why we got the monochrome camera. The camera is connected to the computer by a USB interface with 25 feet of cable going down the tube to the pier under the floor and over to the back of the computer under the observers' desk. We use the program "IC Capture" supplied by the manufacturer to display a live video image on the computer monitor or to record images. The software can produce either videos (at speeds up to 60 frames per second, or time-lapse movies with exposures up to 30 seconds per frame) or single frame snap-shots in bitmap or JPG formats. We bought a lens with the camera. It is a 50 mm focal length lens with a focal ratio of f/1.4. A lens this "fast" is necessary to give live images showing stars as faint as we need for its use as a video finder. Speaking of faint, we can easily see 12th magnitude stars at exposures under one second per frame, and many dim fuzzies like both M81 and M82 show up very nicely on the screen. The camera is permanently mounted on the side of the tube of the 24-inch reflector. We installed a simple cardboard dew cap on the lens to reduce fogging. QOs should be careful putting the dust cover over the front of the telescope. They should not put any part of the dust cover over the camera because that could possibly spoil its alignment with the telescope or defocus it. (Continued next page) Near Infrared Sensitivity The CCD detector chip inside the video camera is sensitive to near infrared radiation (NIR) in the 0.8 to 1.0 micron range. This allows the finder to look through typical light pollution and haze in our sky to some extent, and it gives a performance which is superior to a strictly optical finder. It can also see through thin overcast. We have actually observed the nucleus of M31 through thin clouds at Sperry using the video finder. Because of the enhanced sensitivity to the red end of the spectrum, red stars, both giant and dwarf, will appear brighter on the monitor relative to other stars than they would through an optical finder. This may be the reason we could clearly see both M82 and M81 with the video finder, but could see only M81 at the eyepiece of the 24-inch. M82 contains a lot of H-alpha (red) light in highly disturbed clouds of gas around the central regions of that troubled galaxy. Good Return On Investment For years, the club has contemplated the daunting task of installing digital setting circles on the 24-inch re- flector. Aside from the fact that they give only a marginal improvement in pointing accuracy over the existing setting circles, the interior of the R.A. axis is nearly inaccessible. It was clear that it would be hard to install any mechanical circles and that the project would be expensive. By contrast, the digital video camera and associ-ated accessories cost less than $700, and it took less than two months from inception to final implementation. Faustini Crater Image Used By LCROSS Astronomers By Clif Ashcraft As Told To Ray Shapp The LCROSS Mission In the Summer of 2009, the Lunar CRater Observation and Sensing Satellite (LCROSS) Mission will attempt to confirm the presence or absence of water ice in a permanently shadowed crater at the Moon's South Pole. LCROSS will excavate the permanently dark floor of one of the Moon's polar craters with two heavy impactors to test the theory that ancient ice lies buried there. The impact will eject material from the crater's surface to create a plume that specialized instruments will be able to analyze for the presence of water (ice and vapor), hydrocarbons, and hydrated materials. (The previous info is from the mission website at: http://lcross.arc.nasa.gov/index.htm ) A call went out to amateur astronomers world-wide to assist in imaging the ejected plume. At least two members of AAI have been selected to assist the professional astronomers on Mauna Kea. You can still offer to participate in this program. See contact info for Brian Day of the NASA Ames Research Center on the next page. A Single Mosaic Derived From 90 Seconds of Video The mosaic image of the Faustini crater created by Clif shown below was used by the astronomers on De-cember 7th. The imaging was done with Clif's DMK31 camera looking through a #25 red filter and a NIR block-ing filter which were screwed onto the 1.25" nosepiece of the camera with the optical works of a 2x Shorty Bar-low lens (Orion) screwed onto the end of the NIR blocking filter. By not using the eyepiece tube of the Barlow and just the threaded cell containing the optics, Clif was able to use the lens close to the design 2x amplifica-tion. This configuration gave a focal ratio of f/28 which was a bit oversampled in the red wavelengths passed by the filter combination. The reason for using the red filter is that seeing does not affect longer wavelengths as much as it does short wavelengths. This is enough to offset the lower resolution. An illustration of this configu-ration is shown on the next page. Configuration For Video Imaging (continued from previous page) Stewart's Skybox by Stewart Meyers After a long absence, Venus is now prominently visible in the evening sky and it recently had a close pairing with Jupiter. So, this is as good a time as any to discuss the planet. Venus BS (Before Science) Almost everyone, even the general public, knows that Venus appears very bright and obvious when it is above the horizon. This was probably noticed as soon as our ancestors evolved to the point where they were aware that there were things in the sky. However, it was not until the development of civilization that we have any record that people were aware of Venus. The ancient Sumerians identified Venus as representing Inanna, their goddess of love and fertility. The later Babylonians pretty much copied the Sumerian example and referred to Venus as Ishtar (evidently they never saw the movie with Dustin Hoffman and Warren Beatty) who did pretty much the same things as Inanna. The ancient Greeks, at first, did not grasp that the bright starlike object they saw in the dawn sky some of the time and in the evening sky at other times was actually the same object. Hence, they had two names, Phosphorus when it was seen in the morning and Hesperus when it was seen in the evening. It was a bit later when they worked out the truth. But they were not alone. The ancient Egyptians also thought Venus to be two different objects. The Mayans, however, were not confused. They made quite accurate observations of the motion of Venus in the sky. These have been said to be so accurate that the Mayans could have deduced that Venus went around the Sun, had they been prepared to make that conceptual leap. They did use their knowledge of Venus for their calendar system. Venus did not always inspire love or astronomy. It had a much darker side in the ancient world. Due to a quirk of celestial mechanics, Venus and Mars tend to get close together as seen from Earth about every eight Earth years. While we view such gatherings today as something nice to look at, many very ancient societies interpreted it as the deity they associated with Venus getting together with the one associated with Mars, hence the romantic pairings of the two in a number of mythologies. And this was interpreted as a sign for renewal here on Earth. According to Joseph Campbell, the ancient Sumerians were thought to have killed their king whenever the Mars/Venus conjunction occurred. The Minoans and possibly several other societies also observed this practice. Eventually, ancient kings decided they wanted to rule for longer than eight years, so they wound up abolishing the custom. In the New World, the idea of renewing the fertility of the Earth whenever Venus and Mars drew near through ritual sacrifice was also present, but it took a different turn. For example, the Mayans believed that the close approach of Venus and Mars was a good time to raid a neighboring city, cart off some hapless prisoners, and sacrifice them at the top of the local temple. The Pawnee had a similar but smaller scale idea. They would raid a village and capture a young woman. She was then tied to a platform while a trench was dug next to it. Then she was killed, and her blood dripped into the trench. Eventually, over time, worship of Venus fell out of favor in the Old World (in the New World, it continued until the arrival of the Europeans). I will now end the discussion of the mythological view of Venus with an account that the late Carl Sagan thought was eerily prophetic. In the book of Isaiah (14:12), the prophet refers to Lucifer as the son of morning (Venus in the dawn sky?). Today, Lucifer is another name for Satan, and the conditions of the Venusian surface can be considered pretty much like the classical rendition of Hell. Sagan thought it was amazing that an Old Testament prophet could have insight as to the true nature of the planet. But, it was not as prophetic as Sagan thought. Back in the days of Isaiah, the term Lucifer meant "bringer of light" (the connection of the term with Satan did not take place until the Christian era) and, since Venus appears extremely bright when it is visible in the sky, such an epithet for it was not a big leap of logic. So, what was once thought to be prophecy was actually a coincidence. Venus Science: Beginnings Venus was of interest only to astrologers until 1610. In that year, Galileo decided to point his telescope at the planet. Aside from being the first person to discover that Venus was featureless when viewed through a telescope, Galileo found that the planet shows phases like the Moon does. This was a significant discovery since, in the Earth-centered Ptolemaic cosmology, Venus could never show any phase other than a crescent to a quarter. This was because it was thought that Venus orbited a point in space that followed the Sun, as illustrated in my diagram below. A variant of this idea had the orbit of Venus further from Earth than the Sun, but that would yield only a nearly full phase, without crescents. The only way there could be a full range of phases was if Venus orbited the Sun, which it actually does as illustrated in this diagram of mine below. This discovery confirmed to Galileo the validity of Copernican cosmology. Shortly after the idea that Venus orbited the Sun was accepted, it was found that Venus could pass in front of the Sun in an event known as a transit. The first transit of Venus officially observed was one in 1639 by Jeremiah Horrocks. Studying this transit and the orbit of Venus, Horrocks concluded, correctly, that transits of Venus occur in pairs; each one eight years apart, and each pair is separated by about a century. As the 17th century drew to a close, Edmund Halley realized that if a transit could be observed and be carefully timed from different locations, it would be possible to determine the distance of Venus from the Earth. With this information and knowledge of the relative distances of the planets, the scale of the solar system, could be determined. The next pair of transits would take place in the 1760's and the main astronomical powers of the world, Britain and France, sent astronomers to make observations. In 1761, two surveyors who would achieve fame in North America, Charles Mason and Jeremiah Dixon, attempted to go to Indonesia to observe the transit. Unfortunately, this was during the French and Indian War, and Indonesia was under French occupation. Mason and Dixon changed their plans and went to South Africa instead. Britain fared better in the 1769 transit because it sent out several expeditions. The most famous was that of the HMS Endeavour, under the command of James Cook. The ship sailed to Tahiti where the expedition's astronomers observed the event. The expedition was also significant for the discovery of New Zealand and the claiming of Australia for Britain. While these transit expeditions were successful from a geopolitical standpoint, they were less successful from a scientific perspective. The problem was that it was very hard to time precisely the transits because it was difficult to discern exactly when Venus was touching the inside edge of the Sun. This is known as the "black drop" effect, and its precise cause was something of a mystery until the transit of 2004 when it was found to be due to the combination of seeing effects in the Earth's atmosphere plus optical imperfections of the telescope. Even without a complete knowledge of the problem, astronomers of the next series of transits in the 19th century did find a way to compensate for the black drop effect by using a contraption that moved a dark object on a light colored surface while it was being watched through a telescope. Observers who trained using this device did achieve improved accuracy in their timings. Another transit effect, discovered in 1761 by Russian astronomer Mikhail Lomonosov, was something known as an "aureole", which was a brightening around Venus. Lomonosov correctly reasoned that it was due to light being refracted by the thick atmosphere of Venus. He also went on to claim that this atmosphere was at least as thick as Earth's, if not thicker. Lomonosov's work was not widely noticed in Europe, but confirmation of the existence of the Venusian atmosphere came from the nighttime observations of German astronomer Johann Schroter. While famous for his lunar work, Schroter also observed Venus extensively in the late 1700s. Among the things that proved to him that Venus had an atmosphere was the fact that the terminator (boundary between the sunlit portion and the dark one) was not as sharp as it was on the Moon. He also noted that the cusps (the pointy ends) of the crescent phase extended further than they would have on an airless globe. Backtracking a bit, in 1643, Riccioli found that a faint glow could be seen on the dark portion of the disk of Venus from time to time. This "ashen light" as it was called, lead to quite a bit of controversy over its origin. In 1840, Franz Gruithuisen, a German astronomer, put forth the most outlandish theory to explain this effect. He maintained that the ashen light was the result of huge fires set by the inhabitants of Venus as part of some sort of celebration. Other, more rational, theories include electrical phenomena in the upper atmosphere of the planet and the possibility that the ashen light is nothing more than a contrast effect caused by the brightness of the illuminated portion of Venus. The cause and even the reality of the ashen light is still debated today, with a more modern theory claiming that it is the result of a process similar to airglow in the Earth's atmosphere. What Lies Beneath Once astronomers realized Venus had an atmosphere and that the disk was truly featureless, except for the occasional report of faint smudgy artifacts, most but not all of which were illusions, it was agreed that the atmosphere was totally cloudy. As a result, speculation ranged wildly about what was beneath the clouds as well as what were the basic properties of Venus. One speculation, dating from the late 19th century was that the cloud layer of Venus was made of clouds like we have on Earth. It was logical at the time since water vapor clouds were the only kind anybody was familiar with. This opinion was supported by early spectroscopic measurements made during the transits of 1874 and 1882, which purported to detect water vapor (in reality, the detections were false). In order to provide an unbroken layer of cloud, it was reasoned that there had to be lots of water on Venus, and that the planet had lots of swamps and oceans. The idea of a swampy Venus did fit in with a view of the solar system that dominated very early science fiction (late 19th century to very early 20th century). Mars was thought to be older than the Earth, while Venus was thought to be younger and was expected to resemble the Earth as it was thought to be in either the Carboniferous period or possibly parts of the Mesozoic era. This was the view favored by Swedish astronomer Svante Arrhenius. Naturally, many authors of science fiction latched on to the warm wet Venus model and it cropped up in all sorts of stories, including a vague reference at the end of H.G. Wells' "War of the Worlds", one by Olaf Stapledon ("First and Last Men"), one by a young Isaac Asimov ("Lucky Starr and The Oceans of Venus"), and even Ray Bradbury used it in several short stories. However, that would not be the only speculative version of Venus. In 1921, Vesto Slipher decided to observe the spectrum of Venus at Lowell Observatory. He failed to find evidence for oxygen and other gases that the swampy Venus model would have generated. In 1932, another spectroscopic study was made of Venus at Mt. Wilson Observatory, again yielding similar results. This time, however, the infrared part of the spectrum was studied as well and it showed evidence of carbon dioxide. Since spectroscopy did not support the swampy Venus model, alternatives were put forth. One was the dusty desert model, which maintained that Venus was one gigantic desert and that the clouds were particles of dust. At least this was somewhat plausible. Probably the strangest idea about the surface of Venus proposed by a legitimate astronomer was Sir Fred Hoyle's suggestion in 1955 that Venus had huge deposits of petroleum and other hydrocarbons on the surface. These would remove any oxygen and water vapor from the atmosphere, leaving the carbon dioxide that was being detected. This model also claimed that the clouds were composed of oil droplets. The idea of water on Venus was not totally dead. In 1929, Bernard Lyot (who would gain astronomical fame by inventing the coronagraph) studied the way the clouds of Venus reflected light. He then compared this with how clouds of other substances reflected light. Based on this work, he concluded that the clouds were composed of water vapor. But, there was a problem. The atmosphere that was found via spectroscopy was incompatible with a planet that had seas and land. In 1955, Fred Whipple and Donald Menzel claimed that this problem could be avoided if Venus were a true waterworld for its entire history (just like the one in the Kevin Costner film of the same title). With no exposed land surface, there would be no opportunity for carbonates to form to draw carbon dioxide out of the atmosphere. And, in some versions, the global ocean was slightly fizzy. Even at the late date of 1955, there were still scientists speculating about life on Venus. But, they were soon going to get a reality check. In 1961, scientists at Lincoln Laboratory were able to detect Venus via radar. The actual goal was to determine accurately the distance to the planet, and thereby refine the scale of the solar system. This experiment had a side benefit. For the first time, a reasonably accurate estimate for the rotation rate of Venus was obtained. The initial results indicated a period of 243 days in a retrograde direction (this is quite close to the modern value of 243.16 days). As a result of this rotation and the planet's orbit, it would be 117 days from sunrise to sunset. Not a pleasant prospect. Things would get worse. In 1956, astronomers detected microwave emission from Venus. Normally, planets do not emit strongly at microwave frequencies, so this was seen as odd. In 20/20 hindsight, this should have been seen as an obvious sign that Venus was extremely hot. But, at the time, nobody was sure what to make of it. Some astronomers thought that the microwaves originated from a layer of the Venusian ionosphere and had no bearing on the surface conditions. The Russians Were Coming In the 1960's the United States and Soviet Union were trying to outdo each other in space achievements, including sending spacecraft to other planets, such as Venus. The Russians made the first attempt in 1961, but lost contact with the probe shortly after it left Earth orbit. We didn't do any better. The first American effort came in 196, and it promptly crashed upon launch due to a programming error. However, it was the custom in those days to build and launch probes in pairs, and the second probe, Mariner 2, successfully zipped past Venus in December of 1962. The findings of Mariner 2 put an end to any speculation that Venus had water. It was clearly shown that the microwaves of Venus were the re-sult of its very hot surface. Also confirmed was the slow rotation and, as a surprise to scientists, the total lack of a magnetic field. The Soviets figured that landing a probe on the planet would top Mariner 2's achievements, and they set out to do just that. But, they ran into some problems. Venera (Russian word for Venus) 3 was launched in 1965. It entered the Venusian atmosphere and started sending back its findings, including the discovery that the clouds seen from Earth were not water vapor clouds, but rather they were either water ice or some kind of solution. However, the data came to a sudden halt. Soviet scientists, tracking the descent, were puzzled since the probe should not have been near the surface at the time the transmissions stopped. The answer to this mystery was a major discovery about Venus. It turns out the probe was crushed by the atmospheric pressure, which was far higher than anyone would have expected. U ndaunted, the Soviets tried again in 1967 with Venera 4. While it was stronger than Venera 3, Venera 4 was also crushed, but at a lower altitude than the earlier probe. Meanwhile, the Americans sent Mariner 5 in 1967 to go past Venus. It essentially confirmed and refined the information sent back by Mariner 2. In 1969, the Soviets launched Venera 5 and Venera 6. These didn't quite made it down to the surface, but they did discover that the temperature of the atmosphere was the same whether it was day or night. They also measured the height and thickness of the cloud layer. Learning from the past probes, the Soviets seemed to be getting the hang of exploring Venus. Venera 7, launched in 1970, landed and sent back data from the surface for 23 minutes. Each following lander would add to the record as the Soviets figured out how to chill the landers prior to atmospheric entry. Venera 8 lasted a bit longer, and reported a surface temperature of about 465 degrees Celsius (869 degrees F) sufficient to melt lead, and an atmospheric pressure 90 times higher than that at the Earth's surface. These figures were confirmed and refined by later missions. Starting with Venera 9 in 1975, the landers were equipped with cameras, and each probe took a picture upon landing (except for Veneras 11 and 12 which had camera malfunctions). Veneras 13 and 14 (1981) were equipped with color cameras. No matter where the probes landed, all the images from these missions showed the same thing -- a flat plain with flat rocks stretching to the horizon. Color cameras allowed scientists to deduce what the rocks would have looked like if they could be viewed under white light as opposed to the diffuse orange-yellow light found on Venus. The rocks appeared dark grey, and they turned out to be basalt. While all this was happening, NASA did not totally forget Venus. In 1973, Mariner 10, which was on its way to a Mercury flyby, used the gravity of Venus to aid its travel. One discovery from Mariner 10 was how Venus looked in the ultraviolet. Far from being featureless, Venus had some clouds containing an ultraviolet- absorbing substance. These clouds appear to be blown into shapes resembling a letter "V" or "Y" on its side, hence the name "Y-shaped clouds". By studying these clouds, it was learned that the atmosphere of Venus has a strong jet stream, which circles the planet in four days, much faster than the rate of rotation. Recently, it has been theorized that some of the faint smudgy features seen by astronomers in the past may actually have been the Y-shaped clouds. It is thought that there are some people whose vision has a slight sensitivity to ultraviolet light, and, to them, the Y-shaped clouds would appear as faint, low contrast features. The nature of the ultraviolet absorbing substance itself is still a mystery to this day. Some scientists believe that it is a sulfur compound. However, Dirk Schulze-Makuch at the University of Texas in El Paso has a far more radical idea. He believes that it might actually be swarms of microbes, the last surviving Venusians. This idea is not widely accepted, and I suspect that the actual answer will involve chemistry rather than biology. Mapping The Unseen With a dense cloud layer and also the fact that probes do not last very long on its surface, mapping Venus would seem impossible, but it can be done. In addition to determining the rotation rate of Venus, radar can also be used to map the surface of the planet. In the mid-to-late 1970s, the Goldstone receiver of NASA's Deep Space Network as well as the Arecibo radio telescope were used to make surface maps of Venus. The resulting crude maps showed that Venus had what appeared to be two enormous mountain ranges. Also found were relatively flat plains and some crater-like features. It would take new technology to obtain improved maps.. O Pioneer Venus NASA launched the Pioneer Venus mission in 1978. It consisted of two separate spacecraft. One would go into orbit around Venus and use a synthetic aperture radar system to map the planet. The second spacecraft carried five probes that entered the atmosphere of Venus and transmitted data as long as possible. The mission was a success. As the probes parachuted down, they made detailed measurements of the composition of the Venusian atmosphere. The drop probes found a concentration of the inert gas argon higher than was expected, as well as heightened levels for other inert gases. The reason for this is not yet clear. Also, based on other measurements, it appears that water vapor is much scarcer on Venus than predicted. This is thought to be due to the fact that Venus probably lost most of the water it had early in its history. The clouds were found to be made of a concentrated sulfuric acid solution in a continuous vertical cycle of evaporation and condensation. The Pioneer Venus drop probes were unable to resolve the mystery of the ultraviolet absorbing substance that had been seen earlier in some of the clouds. The clouds themselves form a very thick layer from about 56 kilometers (35 miles) altitude down to about 32 kilometers (20 miles). Below that, the atmosphere is rather devoid of clouds and particles. The drop probes did make it down to the surface, and one survived a short time there, but since they were designed for atmospheric measurements, they returned no useful information from the surface. The Pioneer Venus orbiter was very productive. The radar map constructed from its numerous sweeps of the surface showed a number of surprises. The large mountain ranges found by Earth-based radar turned out to be features more akin to continents. A number of definitely volcanic features were found, and much of the planet, with the exception of the two continents (later to be named Aphrodite and Ishtar), consists of low-lying plains. The Soviets decided they could also do radar mapping, and they launched Veneras 15 and 16, which were equipped with very large radar antennas for the purpose. A few radar images from those missions were released, but they appeared to be of surprisingly poor quality considering the size of the radar antenna. In all, the two probes mapped about a quarter of the planet. The Golden Age of Venusian Ballooning In the final Soviet missions to Venus (1985), VEGA 1 and 2, two probes to Halley's Comet flew by Venus and each deployed a lander as well as a balloon into the Venusian atmosphere. The landers performed experiments on the composition of the local rocks, and the balloons floated at an altitude of 50 kilometers (31 miles) for nearly two days, transmitting information about the winds at that altitude. Magellan, Not Gellin' Initially, following the success of the Pioneer Venus mission, NASA considered sending a mission known as VOIR (Venus Orbiting Imaging Radar) to do a detailed map of the entire planet and to conduct other meas-urements. Aerobraking to slow the spacecraft down for orbital capture was also to have been tested. Unfortu-nately, VOIR suffered from being very expensive and it was not funded. Eventually, NASA came up with another idea for a Venus mapping mission. It was a much simpler space-craft as it was designed only to make a radar map and nothing else. It was to use a spare from the Voyager program as its main radar/radio antenna. This turned out to be cheap enough to get funded, and it was named Magellan, in honor of the captain of the first expedition to circumnavigate the Earth. Magellan was launched in 1989, and it soon arrived at Venus. Once it was in a suitable orbit, the mapping commenced. The results were magnificent. In addition to refined radar images of Aphrodite and Ishtar, Magellan found definite volcanoes with evidence of lava flows. Also, features were detected that have never been seen anywhere before. Huge structures resembling enormous pancakes were found. These are thought to be partially collapsed lava domes. Other evidently volcanic-related features were nicknamed "spiders" and "coronae" based on their appearance on the radar maps. Magellan confirmed a finding of the Pioneer Venus orbiter that showed very few impact craters on Venus. True, the dense atmosphere is partly to blame since all but the largest meteorites burn up before reaching the ground. In fact, there are a few features on Venus, which are interpreted as areas where the ground was af-fected by the shock wave of a meteorite exploding in the atmosphere above it (an "airburst" in simpler terms). But that did not explain the relative scarcity of impact craters. The answer appears to be due to the way Venus dissipates heat from the interior. Magellan never found any feature on the planet that could be linked to plate tectonics (the reason the continents on Earth shift their posi-tions and why we have earthquakes). Without plate tectonics, the options for releasing heat are very limited. There is, of course, volcanism, but that has its limits. Instead it is thought that the heat simply builds up be-neath the crust of Venus until it gets to a critical point where huge sections of the crust actually melt com- pletely, erasing any craters or other surface features. After a time, things cool down enough for the melted sec-tions to resolidify. The process is thought to occur every several hundred million years or so. With its superior resolution, Magellan found details missed by Pioneer Venus. One of them was what ap-pears to be a river channel 4,000 miles long. The problem is that there is no water on Venus and there is probably no area on the surface that would date back to more clement times (see above paragraph). It turns out, however, that a form of lava known as carbonatite could exist on Venus, and carve river channels. While rare on Earth, carbonatite lava derives from magma containing about 50 percent carbonates, with some salts or sulfur compounds. Under Venusian conditions, carbonatite lava has a viscosity similar to water and can flow long distances. Hence, what looks like a river channel is actually the remains of a type of lava flow unique to Venus. The Express Route Currently, the European Space Agency (ESA) has a probe in orbit around Venus known as Venus Express (see http://sci.esa.int/home/venusexpress/ ). It is essentially a spare version of the Mars Express probe with different instruments suitable for studying the atmosphere of Venus. One of the discoveries of the mission is that the circulation pattern of the Venusian atmosphere is much more complex than earlier missions have shown. Using infrared imaging, which allows clouds on the night side of the planet to be studied, Venus Ex-press has discovered huge vortices over the poles. How to Overheat a Planet As most of us know, Venus is closer to the Sun than the Earth is to the Sun, and Venus receives twice the solar energy we do. The Sun has not always been as bright as it is now. In the early days of our solar system, the Sun was about 30 percent dimmer than it is today. At that time, Venus could have had rather Earth-like conditions. However, Venus was doomed. At some point in the past, the Sun gradually brightened to the point where any large bodies of water on Ve-nus evaporated away. The resulting water vapor also functioned as a greenhouse gas driving temperatures higher. Eventually, the water vapor reached the upper atmosphere of Venus where ultraviolet light from the Sun broke it down into hydrogen (which escaped into space) and oxygen, which was eventually incorporated into surface rocks. Even if carbonates had formed on Venus in the more temperate days, the carbonates at the surface would have been broken down under the high temperatures, and their carbon, combined with the oxy-gen would form more carbon dioxide. When it was all done, Venus evolved into the planet we see today. A side effect of losing all its surface water is that any plate tectonics Venus may have had would end because water plays a role in the subduction of crustal plates. The scenario above may be too optimistic. Venus may have been an overheated world almost from the be-ginning. According to a computer simulation by Alex Alemi and David Stevenson of Caltech, Venus was subjected to a collision similar to the one that created the Earth's moon. And, like the collision Earth suffered, a moon formed over Venus. If this were the whole story, Venus might have enjoyed temperate conditions for quite a long time before things got too hot. But more was yet to come. About ten million years after the first major collision, Venus was struck by a second object, which was traveling in the opposite direction. This had the effect of reversing the rotation of Venus. As a result of this change, the newly formed Venusian moon stopped its outward motion and began to move closer to Venus, eventually striking the planet. This slowed the rotation rate to about what we see today and, even with a dimmer sun, it probably resulted in Venus being overheated from that time forward. However, this is only a computer model, and there is no guarantee that this is how events took place. Either scenario yields the same final result though. Reading the above scenarios, you might think that the Earth is safe. And you would be right - for about an-other billion years or so (barring any feats of cosmic engineering). The same process by which the Sun has brightened to its present level is still continuing and, at about a billion years from now (the exact figure depends on which model you use), the Earth will start to overheat and repeat the disaster that befell Venus. The end result will be a slightly cooler version of Venus. The full, gory details can be found in the June 2007 issue of Sky & Telescope magazine. Getting It Wrong and Right Despite the fact that we have known for 40 years that Venus is an extremely hostile planet with high tem-peratures and a toxic atmosphere at high pressure, the popular view of Venus seems to be more benign. As examples, commercials for women's razors or John Gray's book about the sexes show that the mythical view of Venus is still with us. One reference in pop culture, however, actually got it right. On an episode of "Family Guy", Chris Griffin was talking about getting a gift for a girlfriend. Peter, his father, responded with "Listen Chris, I read a book saying that women are from Venus, all right so here's what you get her. Thick layers of sulfuric acid clouds, viscous surface rock, and coronae, which seem to be collapsed domes of large magma chambers. Here's five dollars." While Seth MacFarlane (creator of "Family Guy") goofed with the description of the rocks of Venus being viscous (due to the lack of water, Venusian rocks and geologic features are stiffer than those on Earth), he got everything else about right. Bright Light, Big World As the article has shown, Venus is more than just a bright object in the sky. Much has been learned from studying the planet, and more discoveries will be made in the future. Venus is interesting in its own right. No sensationalism is needed. GENERAL MEMBERSHIP MEETING DECEMBER 19, 2008 "Daring Flight of the Phoenix: Icy Jackpot Hit on Mars (in 3-D)" by Dr. Ken Kremer, NASA JPL Solar System Ambassador and The Planetary Society. Experience the sights and discoveries of the daring NASA Phoenix mission to the icy Martian Arctic tundra. Phoenix is humanity's first mission to dig, touch, and sample life-giving water and to search for a habitable zone on a world beyond Earth. See the custom Martian photo mosaics specially co-created by Ken just days after the landing for the cover of Aviation Week & Space Technology magazine (9 June 08) and continuing throughout the mission also for Spaceflight magazine. Celebrate five years on Mars with the twin rovers; Spirit and Opportunity. Lecture includes spectacular 3-D images placing you "On Mars". Ken is a research scientist and journalist whose articles and space exploration images have appeared in magazines, books, and on websites, including Astronomy Picture of the Day (12 June & 12 Nov 08) and the covers of Aviation Week & Space Technology and Spaceflight magazines. His presentations at educational institutions, civic organizations, museums, and astronomy clubs aim to educate and excite kids and adults about science and space exploration. 8 pm in The ROY SMITH THEATER "Phoenix and the Holy Cow" Photo Mosaic: featured on Astronomy Picture of the Day website on 12 November 2008, in Spaceflight magazine October 2008 issue and Science News magazine online on 13 November 2008. "Holy Cow" water ice layer beneath Phoenix. Ice blasted free by descent rocket thrusters visible at top. Martian soil excavated inside retro rocket blast zone creates depression about 2 inches deep. Mosaic view from Robotic Arm Camera of the feature named "Holy Cow". Astronomy Picture of the Day 12 Nov 2008 "Phoenix and the Holy Cow" http://apod.nasa.gov/apod/ap081112.html Science News Magazine: http://www.sciencenews.org/view/access/id/38521/title/PARTING_SHOT EMAIL CONTACTS presi-dent@asterism.org President of AAI editor@asterism.org Editor of The Aster-ism Ray Shapp, Editor Deadline for submissions to each month's newsletter is the first Friday of that month. member-ship@asterism.org AAI Membership Chair trustees@asterism.org All three Trustees of AAI ray@asterism.org Ray Shapp for the website exec@asterism.org Executive Committee plus Trustees QOs@asterism.org All Qualified Observers Info@asterism.org AAI president, corresponding secretary, and computer services chair research@asterism.org Research Committee technical@asterism.org Technical Committee MEMBERSHIP DUES Regular Membership: $21 Sustaining Member-ship: $31 Sponsoring Member- ship: $46 Family Membership: $5 First Time Ap-plication Fee: $3 Sky & Telescope: $32.95 Astronomy subscription: $34 (Subscription renewals to S&T can be done directly. See "Membrship-Dues" on website for details.) AAI Dues can be paid in person to Membership Chair or Treasurer, or by mail to: AAI, PO Box 111, Garwood, NJ 07027-0111 DOME DUTY December 26 Team D January 2 Team E January 9 Team A January 16 Team B FRIDAYS AT SPERRY December 26, 2008 "Ask Dr. Lew" Dr. Lew January 2, 2009 "What's Up? A Down to Earth Sky Guide" Kathy Vaccari January 9, 2009 TBA Clif Ashcraft All schedules above were accurate at time of publication. Please check www.asterism.org for latest information (click on "Club Activities") DR. LEW'S SEMINARS See Dr. Lew Thomas for possible upcoming seminar topics. (Choice of topic at Dr. Lew's seminars is determined by par-ticipants' interest) January 2009 starts with our saying goodbye to more than just the old year. Folks with a low western hori-zon get about a week to see Jupiter exit the evening sky, not to return until summer. The Giant Planet is soon followed by Mercury which, at magnitude -0.6, has an unusually bright maximum elongation from the Sun. Venus dominates the evening sky all month as it reaches maximum elongation from the Sun on the 14th. Around this time the Evening "Star" is half illuminated and, in a telescope or good binoculars, it looks like a tiny First Quarter Moon. Venus appears to be all alone as it crosses from Aquarius into Pisces, but on the 22nd it passes just over a degree from dim, green Uranus. A week later the two planets and the crescent Moon form a little isosceles triangle, nicely showing a variety of shapes and brightness. Saturn is still a morning object, but it rises well before midnight. The Ringed Planet is starting to brighten again as it approaches its March opposition and its rings start to open after their nearly edgewise position at the end of 2008. The Moon participates in no fewer than six eclipses this year, none of which are visible from New Jersey. The four lunar eclipses are truly terrible, as the Earth's dark shadow misses the Moon completely in the first three and covers less than one-twelfth of the Moon's diameter in the last, on New Year's Eve. The solar eclipses are another matter entirely. The total solar eclipse in July will be spectacular crossing the most heavily populated parts of India and China. At that time the distance to the Sun will be near its maxi-mum and the distance to the Moon will be near the minimum, making the Moon look quite a bit larger than the Sun. This month's annular solar eclipse is the opposite of the July event in every way. The Sun looks extra large since perihelion, its minimum distance for the year, occurred just 22 days earlier. Also, the Moon looks extra small because apogee, its maximum distance for the month, happened only three days before the eclipse. So the Moon cannot come close to covering the entire Sun. Finally, the path of annularity manages to avoid al-most all land areas until just before the Sun sets over Indonesia. The only folks who can really enjoy this event are the 600 residents of the Cocos Islands, weather permitting. NASA Science Outreach and Update by Ken Kremer Mosaic of Phoenix lander footpad to left of large block of water ice, which was cleared of topsoil by descent rockets as the spacecraft touched down near the frigid Martian North Pole on May 25, 2008. Phoenix was spe-cifically targeted to land on icy soils in the Martian arctic to look for organics and other clues to Martian life. The ice layer was found about 5 cm below the surface. A robotic arm camera developed by the University of Ari-zona and Max Planck Institute in Germany was lowered by the arm to take this false-color image of the feature dubbed "The Snow Queen". Astronomy Picture of the Day 12 June 2008 http://antwrp.gsfc.nasa.gov/apod/ap080612.html Aviation Week 9 June 2008 photo mosaic http://tinyurl.com/6ef6bx NASA Science Outreach and Update (continued) Rollback of Space Shuttle Atlantis On October 20, 2008, I attended the "rollback" of Space Shuttle Atlantis off from Launch Pad 39 A at the Kennedy Space Center and back into the Vehicle Assembly Building (VAB) with a press pass. I arrived at the pad in the pre-dawn darkness as the Shuttle stack was brilliantly bathed in floodlights. Atlantis had been scheduled to blast off on October 14 to repair and upgrade the Hubble Space Telescope. The pad rollback was necessitated when a sudden failure of Hubble's on board science data formatter on Sep-tember 27 caused a halt to science operations and forced a launch cancellation. In a rare occasion in shuttle history, both launch pads were simultaneously inhabited. The approximately three and one half mile journey began at 6:45am and lasted about 7 hours. Atlantis was perched atop the Mobile Launch Platform (MLP) and was moved by the diesel powered Crawler-Transporter back to the VAB as I watched from just a few feet away. In a rare opportunity, NASA invited me and a few press folks on hand to photograph the final leg of the rollback from inside the VAB with a birds-eye view on the 16th floor. Atlantis has been rescheduled to launch in May 2009. Astronomy Outreach During October and November, I presented many talks on Phoenix and the Mars rovers to enthusiastic red planet fans at astronomy clubs in four states: New York, New Jersey, Pennsylvania, and Leesburg, Florida for a return visit to "AAI South" at Ernie Rossi's Plantation Astronomy Club. We had a turnout of about ninety peo-ple at Ernie's club. All photos this page credit Ken Kremer Astronomy Outreach (continued) Please contact me for more info or science outreach presentations by email. My upcoming Astronomy talks include: Connerly Road School: Somerset, NJ, Fri, Dec 19, 1PM. "Twin Rovers Explore Mars in 3-D" Amateur Astronomers, Inc. (AAI) at Union County College: Cranford, NJ, Fri, Dec 19, 8 PM. "Daring Flight of the Phoenix: Icy Jackpot Hit on Mars (in 3-D)". Website: http://www.asterism.org Amateur Astronomers Association of Princeton: Princeton, NJ, Jan 13, Tue, 8 PM. "Daring Flight of the Phoenix & 5 Years of Mars Rovers (in 3- D)". Website: http://princetonastronomy.org/activities.html Doylestown Presbyterian Church: Doylestown, PA, Wed, Jan 7, 6:30 PM. "Phoenix and the Twin Mars Rov-ers in 3-D". Website: http://www.dtownpc.org/frames12.html Upper Moreland Middle School: Hatboro, PA, Feb. "Daring Flight of the Phoenix & 5 Years of Mars Rovers (in 3-D)". Dr. Ken Kremer Email: kremerken@yahoo.com NASA JPL Solar System Ambassador Website: http://www.rittenhouseastronomicalsociety.org/Dr.Kremer/K.htm