Volume XX No. 1 September 2008 What's Inside… Table of contents under development. Check back later Note: Use bookmark panel in Adobe Reader. T hat is the question on every amateur (and many a professional) solar observer's mind these days. It seems like the Sun has looked like the H-alpha image in Figure 1 for a couple of years at least, with nary a sunspot to be seen. To be fair, a small sunspot appeared on July 19-21, 2008, and, at the end of March 2008, there were three active regions on the disk at once, with one sporting a sizable spot. Only 21 months ago (December 2006), the Sun produced the largest solar radio burst ever recorded, along with the usual solar X-rays and other radiation associated with solar flares. But still, between these sightings are weeks and months with zero sunspots. s this unusual? Has the Sun gone into another Maunder minimum (see sidebar)? Or is this just the normal behavior of the Sun near its minimum of activity. And if it is normal, when can we expect activity to come back? To find out, let's take a look at the historical record of sunspot activity. If you want to play along, you can view graphs of the historical sunspot record (updated monthly), and download data files to play with in Excel or an-other plotting program. Get the graphs from the Solar Influences Data Analysis Center (SIDC) of the Royal Observatory of Belgium, at http://sidc.oma.be/html/sunspot.html. I Where is Cycle 24? The Sun has an 11-year sunspot cycle, or more generally, activity cycle in which the number of sunspots and all other forms of solar activity rise and fall with a period of roughly 11 years. Sunspots are regions of in-tense magnetic field, which, like one end of a magnet, have either a north or south pole, also called positive or negative polarity, respectively. When the magnetic polarity of sunspots is taken into account, the sunspot cycle is actually a 22 year cycle, with the polarity reversing every 11 years. But for the purposes of this article, we will consider a sunspot cycle of approximately 11 years in length. Sunspots have been observed regularly since Galileo discovered them shortly after the invention of the telescope, although the continuous record began in 1749, and sunspot cycles are numbered from that time. We have just completed cycle 23, and are awaiting the beginning of cycle 24. Signs of cycle 24 have already been reported on January 10, 2008 (see http://science.nasa.gov/headlines/y2008/10jan_solarcycle24.htm ), but, so far, it has been slow in ramping up. Is it too slow? Should we be worried? Figure 2: The lengths of the last 11 solar cycles. Although the solar cycle is said to be 11 years, most of the last 11 are closer to 10 years. Cycle 23 was already 11.8 years as of Feb-ruary 2008, the last month for which we can calculate a smooth monthly mean number. One way to put this question into perspective is to look at the lengths of past cycles. The length of a cycle is defined to be the time between minima of the smoothed monthly mean sunspot numbers. But note that the smoothed monthly means are derived from a 12-month running mean, which means that the number for No- vember 2007, for example, comes from averaging the monthly mean sunspot numbers from June 2007 - May 2008. So at this writing (September 2008), the last month for which we have a smoothed sunspot number is February 2008. As this is written, the mean sunspot number for October 2008 will be coming out in a few weeks, at which time the March 2008 smoothed sunspot number will be available. Thus, solar cycles are like economic recessions. You cannot declare a recession until some months after it occurs. Likewise you cannot determine the end of a sunspot cycle until at least six months after it occurs. To find out the lengths of recent solar cycles, I downloaded the text file of monthly sunspot numbers from the SIDC. Figure 2 shows the lengths of the last 11 solar cycles determined from those data. Even assuming Solar Cycle 23 bottomed out in Febru-ary 2008, the last date for which we have a number, Cycle 23 was a long cycle, especially when contrasted with Cycle 22, which at 9.7 years was the shortest in recent history. Figure 3: Data on monthly mean sunspot number, from the Solar Influences Data Analysis Center (SIDC) of the Royal Observatory of Belgium ( http://sidc.oma.be/html/sunspot.html ). This plot as-sumes a uniform 11 year sunspot cycle. The upper panel shows the raw monthly means, while the bot-tom panel shows the smoothed values using a 1 year running mean. The different cycles are plotted in different colors according to the legend shown. The current solar cycle, Cycle 23, is shown in red. The last six months of smoothed numbers for Cycle 23 in the bottom panel are shown as zero, since they can-not be calculated yet. Cycle 23 is already 11.8 years in length, but we do not yet know its actual length, and, judging by the dearth of sunspots for the past six months, minimum almost certainly occurred after February 2008. So we can be quite sure that Cycle 23 is one of the longer, and perhaps the longest, of the past 11 cycles. This is one reason that Cycle 24 seems late. To get another perspective, I plot the last 5 cycles in Figure 3 above, assuming a cycle of exactly 11 years. The upper panel is the mean monthly sunspot number, while the lower panel is the smoothed monthly sunspot number. Cycle 23 is the red curve. I have arbitrarily counted the current month (September 2008) as the last month of Cycle 23, and count backward by 11 years at a time to set the corresponding year zero for each pre-vious cycle. The first thing to notice about the upper panel of Figure 3 is that the sunspot number varies greatly on a monthly timescale, so pinpointing the maximum and minimum of a given cycle is not that easy. Looking at the smoothed sunspot number in the lower panel of Figure 3, however, we can see that the rise and the peaks of the various cycles do not match up very well, reflecting a fact we already know. Sunspot cycles are not all 11 years in length, and this fact makes it even harder to say for sure when we should expect Cycle 24 to begin. Relative to the rise and peak times of Cycles 19, 20, and 21, it appears that Cycle 22 rose a year early, and Cycle 23 rose two years early. Note also that Cycles 22 and 23 show a double peak. It is hard to say anything definitive from Figure 3 about whether Cycle 24 is late or not. The same information is plotted again in Figure 4 (see next page), but here I have used the actual cycle lengths shown in Figure 2. Now the rises and decays all align fairly well, although the peaks occur at quite dif-ferent times. When plotted this way, Cycle 24 does appear rather late, and the actual sunspot number is slightly lower than the others. Cycle 23's behavior is closest to that of Cycle 20, which was also a long one. Taking Figure 4 as an indicator, Cycle 23 is not unusual yet. But if we do not start seeing activity rise soon, Cycle 23 will start to become an historical oddity. The sunspot number from 1600 to 1995, showing the period called the Maunder Minimum when the sunspot number was essentially zero for more than 50 years. Data was obtained from NOAA's National Geophysical Data Center: ftp://ftp.ngdc.noaa.gov/STP/SOLAR_DATA/SUNSPOT_NUMBERS/GROUP_SUNSPOT_NUMBERS/ monthrg.dat Solar Cycle 24 Predictions What are the experts saying about Solar Cycle 24? Will Cycle 24 be large or small, early or late? NOAA and NASA convened a panel in April 2007 to come to a consensus prediction of the next solar cycle. The report can be viewed at http://www.swpc.noaa.gov/SolarCycle/SC24/. Interestingly, predictions based on different methods came out on both sides of the question, and could not be reconciled. One group predicted a higher than normal cycle, peaking in 2011, while the other predicted a lower than normal cycle, peaking in 2012. However, both groups agreed that the minimum should occur in March 2008, plus or minus 6 months. But again, the minimum is based on monthly sunspot numbers smoothed over 1 year, and it is too soon to know if the minimum has already occurred or not. (Continued from page 4) Figure 4: Data as in Figure 3, but now using the actual cycle lengths from Figure 2. The upper panel shows the raw monthly means, while the bottom panel shows the smoothed values using a 1 year running mean. The different cycles are plotted in different colors according to the legend shown. The current solar cycle, Cycle 23, is shown in red. The last six months of smoothed num-bers for Cycle 23 in the bottom panel are shown as zero, since they cannot be calculated yet. (See conclusion on page 6) Figure 5 shows Solar Cycle 23 data and the prediction for Cycle 24, from the NOAA/SEC press release at http://www.swpc.noaa.gov/SolarCycle/SC24/. This shows that the smoothed monthly sunspot number should start to rise around Jun 2008, and, by end of 2009 or early 2010, we should be half way to the peak of the cy-cle. Although we have not seen it yet, the prediction is that solar activity is going to come back soon. I for one am rooting for the group predicting a larger than average cycle. So dust off those solar filters, and start saving for a Coronado H-alpha telescope. Figure 5: Solar Cycle 23 data and predictions for Cycle 24, from the NOAA/SEC press release at http://www.swpc.noaa.gov/SolarCycle/SC24/. The predications panel could not reach a consensus, and issued two different predictions shown by the two red curves. Both predict a return of activity starting around March 2008. Covering the Next Solar Maximum Scientists are gearing up for Solar Cycle 24 with new ground- and space-based instruments for studying the Sun and the heliosphere (the space around the Sun). At NJIT, the new 1.6m optical telescope is nearing com-pletion at Big Bear Solar Observatory ( http://www.bbso.njit.edu ). When finished, it will be the largest solar telescope in the world, and will be outfitted with both active and adaptive optics to enable extremely high reso- lution imaging. NJIT is also part of a university consortium to build the Frequency-Agile Solar Radiotelescope (FASR) ( http://www.fasr.org/ ), which has now been proposed for construction. When complete in 2012, it will image the Sun in radio waves from 50 MHz - 21 GHz, with spatial resolution and image quality far better than has been available before now. In space instrumentation, the Solar Dynamics Observatory (SDO) will be launched in December 2008. It will be a super-SOHO, taking terabytes per day of images and spectra in the Extreme Ultraviolet, and measuring magnetic fields and helioseismic waves on and in the Sun. Other planned spacecraft include the long awaited Solar Probe (just announced, but launch date TBD), and the European Space Agency's Solar Orbiter (planned for a 2015 launch). Meanwhile, SOHO, Trace, RHESSI, STEREO and Hinode all continue to operate. (Ed note: except where indicated, all graphics in this article are original works by the author.) Clearing an Orbit's Neighborhood By Mike Luciuk What are the Requirements? T he current International Astronomical Union (IAU) definition of a solar system planet requires that it clear its orbital neighborhood. As a result, there are now the eight planets and four "dwarf planets," Ceres, Pluto, Makemake and Eris. This paper will examine the gravitational factors involved in the "clearing" task and discuss methods to assess planetary classification. 1. Role Of Escape Velocities To clear its orbital neighborhood, a body must, meet the following requirement: The most stringent criterion for clearing planetesimals is that the surface escape velocity - which is the maximum velocity that one body can impart on another through gravitational inter-action - be greater than the local escape velocity from the central star. A body of such mass will be able to scatter other small bodies beyond the gravitational influence of the star (Basri, Brown, 2006). When a body's surface escape velocity exceeds that of the Sun at its location, it has the capability of either accreting a smaller body or ejecting it from its orbit, thereby facilitating clearing. Ejection of less massive planetesimals might be accomplished by a gravity assist, thereby increasing or decreasing the velocity of the planetesimals. It should be pointed out that while this is a necessary requirement to clear an orbital neighbor-hood, it may not be sufficient.. Other considerations like the presence of massive planets or resonance effects may be important. Figure 1 illustrates the Sun's escape velocity from ranges of 1 to 100 AU. As shown, the Sun's gravitational influence extends to great distances. However, at the Oort cloud, about a light year away, the Sun's escape velocity is only about 0.2 to 0.3 km/s. Its influence is so small that perturbations from passing stars can dis-lodge icy planetesimals that may then arrive near Earth as long-period comets. The surface escape velocity of an astronomical body is given in Equation 1: (1) (1) Where v = escape velocity in m/s, G = the gravitational constant 6.672 x 10-11 m3 / kg s2, m = the body's mass in kg, and r = the body's radius in m. Table 1 shows the escape velocities for several planets and "dwarf planets": ASTRONOMICAL BODY Mercury Earth Mars Ceres Jupiter Neptune Pluto ESCAPE VELOCITY (km/s) 4.4 11.2 5.0 0.51 59.5 23.5 1.2 Table 1. Surface Escape Velocities The asteroid belt (Figure 2) lies between Mars and Jupiter, roughly from 2.1 to 3.2 AU with only about 0.0006 Earth mass. It was formed as a result of Jupiter's gravitational force, creating perturbations that pre-vented the formation of a small planet from surrounding planetesimals. Figure 2 also illustrates the positions of the Trojan and Greek asteroids which are under Jupiter's gravitational influence at the L4 and L5 Lagrangian points. The Hildas are asteroids in 3:2 resonance with Jupiter. The orbit of Ceres has a semi-major axis of 2.8 AU, placing it in the midst of the main asteroid belt. Its 0.51 km/s escape velocity is unable to match the local Sun's 25 km/s escape velocity to clear its orbital zone. The main Kuiper belt (Figure 3) resides approximately 35 to 50 AU from the Sun. It is estimated to have about 0.1 - 0.3 Earth mass. In a similar fashion to the asteroid belt, Neptune's gravitational force perturbed the trans-Neptunian comet-like planetesimals. Pluto's aphelion is at 49.3 AU, and its perihelion is at 29.7 AU. Most of its orbit is within the Kuiper belt. At no time in Pluto's orbit can its 1.2 km/s escape velocity approach the Sun's local escape velocities of 6.0 km/s at aphelion or 7.7 km/s at perihelion. Its limited gravitational force cannot clear its orbital neighborhood. Examining Table (1), it is quite certain that if Mercury or Mars were in Pluto's orbit, they wouldn't be able to clear their zones either, but in theory, Earth could. However, Neptune's influence would probably prevent Earth from being successful. 2. Clearing Parameters For Planet Classification The preceding section discussed the basic requirement for a body to clear its orbital zone. We'll now com-pare two methods of characterizing the extent to which gravitational dominance affects the structure of the solar system. Stern & Levison's Scattering Parameter, ) Steven Soter (2006) summarized research about the subject of neighborhood clearing by Stern and Levison (2000). They derived a clearing parameter, ) that characterizes the ability of a body to scatter planetesimals, given sufficient time: (2) Where k is approximately constant with a value of 1.5 x 105, and M and P are the scattering body's mass and period. Major body values for ) are given in Table 2. Bodies that have cleared a large percentage of their or-bital area have a ) > 1. There's obviously a clear division of clearing capability, with the three "dwarf planets" having ) values four orders of magnitude smaller than Mercury's. However, Stern and Levison still regarded Ceres, Pluto and Eris to be planets, but of a smaller class. BODY MASS (ME) ? Scattering parame-ters µ Planetary Disrimi-nants Mercury 0.055 1.9 x 101 9.1 x 104 Venus 0.815 1.7 x 105 1.35 x 106 Earth 1.000 1.5 x 105 1.7 x 106 Mars 0.107 9.3 x 102 5.1 x 103 Ceres 0.00015 0.0013 0.33 Jupiter 317.7 1.3 x 109 6.25 x 105 Saturn 95.2 4.7 x 107 1.9 x 105 Uranus 14.5 3.8 x 105 2.9 x 104 Neptune 17.1 2.7 x 105 2.4 x 104 Pluto 0.0022 0.003 0.07 Eris 0.0028 0.002 0.10 Table 2. Scattering Parameters and Planetary Discriminents (Soter, 2006) Figure 4 (next page) plots the scattering parameter, delta, based on mass (relative to Earth) and semi-major axis. The solid lines intersect Mars at delta of 930 and Pluto of 0.003. The dotted line is at delta = 1. (Continue next page.) (Continued from page 9) Soter's Planetary Discriminant Parameter, : Soter (2006) has devised a planetary discriminant factor, µ that he uses to define a planet: (3) Where M is the final body mass after accretion and m is the total aggregate mass of other bodies in its orbital zone. If : > 100, Soter deems the body to be a planet. He references many sources to determine the other body total mass for his m parameter. If a body's mass (M) is more than 99% the total mass (M+m) in its zone, it is considered a planet by Soter given its gravitational dominance. Table 2 lists the µ values and there's a large difference between the discriminant factors of the three "dwarf planets" and the eight planets. In Pluto's case, its mass is only 7% of the remaining total mass in its orbital zone, not at all dominant. Figure 5 plots the µ parameter for solar system bodies based on their mass M, and the aggregate mass of other bodies in their orbital zone, m. The upper solid line represents Mars' µ of 5,100 and the lower solid line is Ceres' µ of 0.33. The dotted line is a µ of 100, representing Soter's division of planets versus smaller bodies. 3. Final Remarks Comparing a scattering body's escape velocity to that of the Sun is an unambiguous way to determine its potential to clear its neighborhood, but not necessarily its success in doing so. Although the Stern/Levison ()) and the Soter (µ) dynamical methodologies differ in their approaches, their conclusions are very similar. The two graphs are strikingly similar. They agree that orbital clearing capability of the eight planets is vastly greater than that of the "dwarf planets." The Stern/Levison methodology is theoretically oriented, requiring a scattering body's mass and orbital period to predict clearing potential. Soter's procedure also requires the scattering body's mass, plus an estimate of the total aggregate mass of the remaining bodies in its orbital zone, thereby determining its gravitational dominance. Planets are the large bodies that have prevailed in the formation of the solar system and have shaped its ar-chitecture. They have emerged as the major bodies either via accreting smaller bodies or scattering them. Dwarf planets are bodies reaching hydrostatic equilibrium, which also implies they have a differentiated struc- ture. However, they do not have gravitational dominance of their orbital zone and are in a separate planet class. This makes the recognition of planets versus dwarf planets quite straight forward, since the ability to clear smaller bodies makes them distinctive against background debris. There are no upper limits (except fu-sion mass) or lower limits to a planet's mass, only its ability to become the gravitationally dominant body by clearing its orbital zone. Ed note: The references for this article are on page 17. Stewart's Skybox by Stewart Meyers D uring the summer break, I became registered as one of AAI's presenters for the Night Sky Network ( http://nightsky.jpl.nasa.gov/ ), a program operated by NASA's Jet Propulsion Lab and the Astronomical Society of the Pacific ( http://www.astrosociety.org/ ). The main goal of the program is to increase public awareness of specific NASA missions as well as space science in general. One of the perks of membership is that I get access to webcasts that NSN hosts from time to time. The most recent one of these, back in August, was devoted to the LCROSS (Lunar CRater Observation and Sensing Satellite). This mission involves using the Atlas-Centaur upper stage that launched the Lunar Reconnaissance Orbiter as an impactor to hit a per-manently shaded crater in the south polar region of the Moon. The impact is expected to launch a cloud of debris into space, which will be studied by a small probe flying some distance behind the impactor as well as by ground based observations from professional and amateur astronomers. The purpose of this exercise is to settle the question of whether or not there is ice in the lunar soil of these dark craters. Since the LCROSS mission hasn't launched yet, I will devote this article to why scientists think there is ice in those craters and that it is worth the effort of this mission to find out. The LCROSS mission itself will be the subject of a future article. Lunar Seas For most of human history, little thought was given to the actual composition of the Moon. Sometime in the second century AD, Lucien of Samosata wrote a story called "A True History" which imagined the Moon to be very much like the Earth. However, this story was merely a piece of humorous satire and was not based on any real knowledge. Even though the light and dark markings of the Moon are visible without any optical aid, there was little speculation as to their nature besides the mythological explanations (ie. the "Man in the Moon"). The first per-son who seems to have given the matter any real thought was no less a figure than Leonardo da Vinci. While pondering the question of why it is possible to see the dark portion of the Moon when the Moon is in a crescent phase, Leonardo thought about the light and dark markings. He reasoned that the dark markings did not reflect that much light and must therefore be land. By this logic, the bright areas were seas. Despite this erroneous view of the lunar surface, Leonardo correctly explained that the reason we can see the portion of a crescent Moon that the Sun isn't shining on is because it is being lit by sunlight reflected from the Earth (Earthshine). When telescopes were first invented and pointed at the Moon, the crude optics revealed craters in the bright highlands, but the darker areas looked smooth. This, coupled with the bay-like indentations on some of the highland regions prompted some early astronomers to refer to the dark areas as seas. Telescopes quickly im-proved enough to reveal craters and other features in the dark areas. But, Riccioli's system of naming lunar features had caught on, and the term "mare" (Latin for "sea") to name the dark areas stuck. The early telescopic work was enough to drive the idea of water on the Moon largely into the realm of fiction. Lunar bodies of water would crop up occasionally in works such as the "Moon Hoax" articles by Richard Locke (1835), and finally in "First Men in the Moon" (1901) by H.G. Wells, though Wells had thought enough to keep his lunar lakes underneath the lunar surface which explained why they were never seen from Earth. But the idea of actual lunar seas was not totally dead. One of the more outlandish theories to explain the craters of the Moon was put forth in the 19th century and it proposed that, since lunar craters are round, they (or at least the crater rims) must be enormous coral atolls formed at some point in the distant past when there was liquid water on the lunar surface. The next-to-last professional astronomer to suggest liquid water on the Moon was William Pickering, who, in the very early 20th century thought that the lunar rilles might be the remains of rivers. But, by that time, he was pretty much considered a crackpot and almost nobody took his view on rilles seriously. However, this idea, in a slightly different form, would surface again in the 1960's as will be shown later in this article. As more was learned about the nature of space, some astronomers figured that, if there wasn't liquid water on the Moon, maybe there was ice. Ice Moon of the Nazis In 1894, Hans Horbiger, a German refrigeration engineer by day, amateur astronomer by night, had an idea. Looking at the full Moon, he concluded that the Moon and many other objects in space were actually made out of ice, and that ice was a major constituent of the universe. Evidently, he was fooled by how bright the full Moon appears at night. We know that the real reason the full Moon appears bright is because the weakly re-flective Moon is seen surrounded by non-reflective space. But Horbiger did not know this. In the years before World War I, Horbiger wrote some papers to publicize his view of ice cosmology. However, this theory was immediately rejected by almost all, except a few Christian fundamentalists who used it to try to justify the global flood in the book of Genesis. Horbiger died in 1931, and, shortly after that, a man with the unusual name of Houston Stewart Chamberlain rediscovered Horbiger's theory and started publicizing it in Germany. Unlike the very poor reception the idea got the first time, the ice Moon/Cosmos theory gained a very influential and powerful advocate - Heinrich Himmler. As a result of Himmler's effort and a half-hearted endorsement from Hitler himself, Horbiger's theory became the officially endorsed cosmology of the Third Reich. There were two reasons Horbiger's Ice Cosmos appealed to the Nazis. One was that it fit nicely with the hideously distorted version of Nordic mythology that the party embraced. Secondly, it was considered a blow against what the Nazis perceived as "Jewish science". Needless to say that Horbiger's cosmology pretty much died with the Reich in 1945. In 1942, a lunar crater near Mare Nubium and the Straight Wall that had been named after Horbiger was re-named in honor of Henri Deslandres, the French astronomer who invented the spectroheliograph. One won-ders if the association of Horbiger's work with the Nazis had anything to do with this change. Cold Moon vs. Hot Moon When the possibility of sending spacecraft to study the Moon became plausible, there were two competing views of the composition of the Moon. One view maintained that the Moon had been hot enough in the past for heavier elements to have sunk towards the center and lighter elements to have come to the surface. This is called differentiation. Also, this view was bolstered by the opinion that there was evidence of past volcanic ac-tivity on the lunar surface. Another view, proposed in 1952 by Harold Urey, a geochemist best known for an experiment which used electric sparks to create organic molecules from a mixture of gases that was believed to be similar to the at- mosphere of early Earth, was that the Moon was never hot enough to differentiate. Urey was inspired by the low density of the Moon that he felt was the result of being composed of the same materials as some of the more primitive meteorites. By this logic, the Moon should represent a sample of material from which the inner solar system had formed. Since the Moon never reached high temperature in this model, it was referred to as the "Cold Moon". One consequence of Urey's theory was that there was the possibility of water-bearing minerals on the Moon, such as those found in certain primitive meteorites. Also, a paper published in 1968 by Robert Lingenfelter elaborated on this idea. He believed that water from some of the water bearing minerals deep in the Moon might migrate towards the surface, freeze at a shallow depth underground, and form a layer of permafrost. The occasional impact would melt some of this layer, which would flow for a short time as a river and form rilles. For some odd reason, Lingenfelter's theory was still cited in P. Clay Sherrod's book "A Complete Manual of Amateur Astronomy". But the Apollo missions would settle the question of hot vs. cold Moon once and for all. The rocks brought back by the astronauts turned out to represent a small range of minerals, mainly igneous rocks such basalt and metallic oxides, and they proved that the Moon did undergo a very hot phase in its early history where there was some differentiation. What should have been the final nail in the coffin of water or ice on the Moon was the so-called "Big Splat" theory of the Moon's origin. This states that, early in the solar system's history, a planetesimal the size of Mars struck Earth in a glancing impact. Debris from Earth's mantle, as well as from the impactor eventually accreted into the Moon. Under such conditions, nothing besides rock and metal could survive. (Continued next page) Where the Sun Don't Shine Even though things looked very bleak for the idea of ice on the Moon, there was a small loophole. Because of the Moon's orbit nearly in line with the plane of the ecliptic and its low axial tilt, sunlight never reaches the floor of some craters at the lunar poles. As a result, these crater floors are among the coldest spots in the inner solar system. The Moon is subjected to occasional cosmic impacts. Most of these are quite small and involve meteoritic debris. Others are of bits of asteroids. Then there are impacts by comet nuclei and fragments of comet nuclei. Since the Moon has no real atmosphere, objects strike the surface at whatever speed they were traveling through space. In the case of comet impacts, the icy materials, including water ice, of impacting nuclei are in-stantly vaporized. Because of the weak gravity of the Moon, most of this vapor escapes immediately into space, and the rest is usually gone in a short time. However, imagine a comet impact near the lunar poles. Some of the vapor could get into one of those per-manently shadowed craters mentioned earlier. Exposure to such cold temperatures would instantly freeze the constituents of the vapor, and the resulting icy crystals would fall to the lunar surface. Over millions of years, a substantial amount of ice could accumulate in the shadowed craters. By the 1990s some scientists were think-ing of ways to test this theory. Clementine In the 1990s, the Ballistic Missile Defense Organization (BMDO), decided to prove it was possible to rapidly build and launch a space mission with a low budget. The rationale was to show that a spacecraft to deal with threatening asteroids could be built in short order, and also to justify the BMDO's existence. The result was Clementine. This was a mission to study the Moon at fairly high resolution (and to test sensors that would be used in future asteroid missions). It was launched in 1996. The point of Clementine that is relevant to this story happened near the end of the mission. Radio signals were directed from Clementine into craters at the lunar poles, and the reflected signal was detected on Earth. It was essentially an improvised radar system. Since ice reflects radio and radar signals in a way different from rock, this method should be able to detect ice. There were some positive results. However, later radar tests using the Arecibo radio telescope as the radar dish failed to confirm these findings. Another method was called for. To the Moon, Eugene In 1998, NASA launched the Lunar Prospector mission. While the main purpose of this mission was to map mineral distribution on the Moon, it would also try to confirm the findings of lunar ice made by Clementine. However, instead of radar, Lunar Prospector used a different method. One of the instruments on Lunar Prospector was a neutron spectrometer. Cosmic rays that strike the lunar surface produce neutrons. Some of these neutrons would have high energy, and shoot directly into space. Other neutrons would have less energy, and tend to bounce off any hydrogen atoms until they leave the lunar surface. The spectrometer would measure the ratio of the two kinds of neutrons, and that would yield an esti-mate as to how much hydrogen was in a given region. The results from Lunar Prospector seemed to indicate enhanced levels of hydrogen in a few areas of the lu-nar poles. This is consistent with ice in the shadowed craters but is not absolute proof since other hydrogen compounds would produce similar results. At the very end of the mission, one last effort was made to confirm the presence of lunar ice. Lunar Prospec-tor was commanded to crash inside one of the shadowed craters. It was hoped that the impact would vaporize some of the ice, and that would be detected from Earth. Also, there was some hope that the debris cloud from the impact would be visible from Earth. Unfortunately, this final maneuver did not yield any results. There are several possible reasons. One is that the impact simply did not have enough kinetic energy to do the job. An-other is that the surface in the crater was as hard as rock and would not create a debris cloud. Thirdly, there might be a problem with the lunar ice theory. Some good was accomplished in the crash, though. Inside Lunar Prospector was a canister containing some of the ashes of the late Eugene Shoemaker, the man who proved lunar craters were formed by impacts. In the 1960's, Shoemaker tried to join the Apollo program but was cut for medical reasons. So, while he failed to go to the Moon in life, he got his wish after death. Space: 2009 In 2009, NASA will try again to prove the existence of lunar ice with the Lunar CRater Observation and Sensing Satellite (LCROSS) mission ( http://lcross.arc.nasa.gov/ ). Essentially a much more powerful and so- phisticated version of what was attempted with the crash of Lunar Prospector, LCROSS is believed to be ca-pable of proving whether the hydrogen readings from Lunar Prospector were the result of ice or possibly some other hydrogen compound. So, watch this space in 2009 for more details on this mission. Once Upon a Time at Stellafane by Bonnie B. Witzgall © The Springfield Telescope Makers (STM) of Springfield, Vermont conduct an annual event called "Stellafane Convention". With so much to do and learn, they had no choice but to extend Convention an extra day. As-tronomers come together from around the globe and eagerly share in so many aspects of astronomy and tele-scopic instruments. Originally begun as a two-day telescope maker's convention in southern Vermont, Stella-fane blossomed into a non stop astronomical paradise with many presentations and events. Now the experi-ence runs for three days with demos of grinding and testing telescope mirrors, CCD photographic classes, and telescope competitions all under clear mountain skies. Lectures of all things astronomical are held in the after-noons and evenings, and are always well attended. Although telescopes look at objects "in the past", the STMs of Springfield have an eye to the future, and they offer many children's activities and workshops for young sky viewers. Even with the new three-day Convention time, many events overlap each other. People wind up run-ning from the Swap Table (non commercial flea market just for astronomers) to the Tent Talks and up to the telescope judging. Then it's on to the Turret Telescope, down to the McGregor Observatory to see the "Super Schupmann" 13-inch refractor, and out to the observing field for horseshoe pitching. It's tough to experience everything at once, but taking the shuttle bus throughout the campgrounds does save time. However, a cloning device or a Time Machine would serve better. Since that technology is imprecise at best, you learn to wisely budget your time and space at Stellafane. During most years, it is time well spent. Good weather and a dry campground signaled a fine start for the 2008 Convention, the 73rd year of Stella-fane. Alas, the current price of gasoline and tough economic times cut back on this year's crowd. Avid as-tronomers will always explore the sky, but, like anything else, cost overruns alter the timing of the mission. As soon as Al Witzgall and I pulled into our favorite campsite, we began the task of pitching the tent. We are vet-erans of Stellafane, and know that the weather can change in the blink of Algol, so we quickly set up our shel-ter and secured a parking spot. AAI members, Irene and Richard Greenstein, joined us and pitched camp un-der the pines next to a piece of campground called "Brian's Place", named for AAI member, Brian Lemley. Once the bivouac was in place, the non-stop time table could begin. We scattered and searched for members of the Springfield Telescope Makers who were current or former members of AAI. An AAI group photo was planned, and attendees were expected to come together at noon on Saturday. Weeks before the Convention, AAI members planned to have this group photo, but the hardest task would be to gather everyone together at one time and in one place for this picture. Irene was actively endors-ing the good times at Stellafane, encouraging all members to make the effort to attend the Convention and to be part of the photo. With so much to do and see, however, it's hard to schedule a photo shoot with such busy people. Before the main festivities began, some of us happened to visit the local hardware store… and just happened to encounter a former member of AAI. Reverend Al Tinker, an AAI eclipse expedition leader and telescope fund-raiser who was also attending the Stellafane Convention. He readily agreed to be part of the club's photo. It was Blessed Timing! During the day on Friday, AAI member, Kevin Walsh, and his young daughter, Amanda, "happened to find us" and consented to be in the group picture. Kevin said that AAI'er, Brian McGuiness, had no free time to stop by and tell us "yes" in person, but he promised to be there. On Friday night, AAI and STM member Melinda Callis had fallen and so could not attend the group photo (A painful case of Bad Timing). Later that same night, Al just happened to attend a CCD imaging workshop at the McGregor Observatory. That site is a red-light-only district and the attendees had to tread carefully from the building into the observing field. As he cautiously stepped from the observatory's front door, Al became aware of two grinning faces staring right at him, each face half lit by a red flashlight. It was two people both named Marcus Valdez. They are father and son, and both are members of AAI. They had driven from their New Hampshire vacation to Springfield in the dark, and had never before at-tended Stellafane. Rosemary and husband Marcus Jr. had not made previous reservations in Springfield's only hotel, and had no way of contacting any of the AAI crowd at Convention. Somehow, they and their young son were able to navigate downtown Springfield and happen to find a vacancy in the local hotel. Marcus Jr. and Marcus III then traversed the winding dirt road in the dark to the Convention site. Then the skillful timing con-tinued because amid hundreds of fellow astronomers, they were able to connect with an astonished Al in the darkened observing field, lit only by an intense Milky Way. It was Miraculously Perfect Timing! Saturday morning began at sunrise with the Swap Table area. The 'official' time for this astronomer's flea market is 8am, but savvy shoppers begin bargaining around 6am (Too Darn Early Timing). Thus begins the non-stop Saturday marathon at Stellafane with simultaneous events and concurrent programs. For the Spring-field Telescope Makers, timing is everything in staging their great Convention. It's also an issue for attendees who want to satisfy their annual desire to attend everything at once. Because of all the real-time events, the Valdez Family missed most of the Swap Table (Disappointing Time). The one remaining merchant was pack-ing away his wares. He sold a basic astronomy book to Al for a good price, which Al proudly gave to Marcus, III. Young Marcus immediately sat down in the empty field and immersed himself in the printed word (a Good Time for reading). It was a hard feat for AAI members to tear themselves away from the daytime festivities, and convene for the club's group photo. "Hurry! Hurry!" We must take the picture before the sky becomes too cloudy and the sunny time ends. Oh, but we had to wait for the stragglers to come from different places within the Convention. So much hilly acreage between each event site, it takes time to move between venues. Finally, the AAI crowd assembled together for just a moment in time, and the Club Photo was recorded. Then, it was a mass scatter-ing of bodies and minds all moving on to various places. Too many things to do at Stellafane, too little time! The final Convention event was on Saturday evening. The Springfield Telescope Makers of Springfield, Vermont who make Convention happen plus the 2,000 attendees came together for one final time. People from all over North America, plus visitors from Germany attended this year's event. The keynote lecture, door prizes, and telescope awards took place in the huge Flanders's Pavilion. It's a monstrous 6,000 square foot structure 60 feet wide by 100 long by 16-feet high. Its huge sliding walls can either welcome in all the daytime sunlight or nighttime darkness or keep out uncooperative weather. That evening's rainstorm and foggy condi-tions stayed outside while the audience experienced a dry and entertaining time to end this year's conference. This year's Stellafane Convention brought together astronomers from all over the world to commemorate the 400th Anniversary of the invention of the telescope. The year 2009 is designated as the International Year of Astronomy (IYA). All the Stellafane attendees agreed to promote astronomy in their local areas, and to carry the torch of enlightenment. The 2008 Amateur Astronomers, Inc. group photograph created at Stellafane is just a momentary snapshot of time and space. In that place and at that time, members stood united and proudly represented their home base in Cranford. Everyone in that photo renewed their heart-felt commitments of skill- ful timing, good friendship, and willingness to come together for a common cause. The AAI photo is actually a small sample of the entire Convention's foundation. Now would be the time for someone reading this story to join the Stellafane conventioneers and AAI to help endorse the International Year of Astronomy. It will be time and effort well spent. Clearing an Orbit's Neighborhood (Continued from page 10) References Basri, G., Brown, M., 2006, Planetesimals to Brown Dwarfs: What is a Planet? The Annual Review of Earth and Plane-tary Science. http://en.wikipedia.org/wiki/Asteroid_belt http://en.wikipedia.org/wiki/Kuiper_belt Soter, S., 2006. What is a Planet? The Astronomical Journal Stern, S. A., Levison, H. F., 2000. Regarding the Criteria for Planethood and Proposed Planetary Classification Schemes, Transactions of IAU. Welcome New Members Amateur Astronomers, Inc. welcomes the following new members to our club: Reverend William Whitehead, Amaru Alzogaray, Rachel Zuckerman, Joseph Romero, George Bottarini, James V. Heck, and Edward Ahearn. We hope you enjoy using Sperry Observatory and all the opportunities available to you as members such as seminars, lectures, training, observing, and research. Our Qualified Observer course is a great place to start. It is equivalent to a college-level introduction to Astronomy and it includes hands-on training on our 24-inch re- flecting telescope. For this and other opportunities, check the Club Activities section of the website. Again, welcome to AAI! Irene Greenstein. Membership Chair Membership@asterism.org GENERAL MEMBERSHIP MEETING SEPTEMBR 19, 2008 The story behind the Hubble Space Telescope is a story of many near deaths and amazing saves. Repeatedly, politicians, bureaucrats, scientists, and even astronomers, made passionate efforts to stop its construction or terminate its use. Repeatedly, these efforts failed, as even those who originally opposed the telescope found that they could not resist its allure. The compelling nature of the unknown that the telescope promised to unveil won out each time. In describing the heroic and unknown story of the men and women who conceived, de-signed, built, and saved Hubble, award- winning science journalist and historian, Robert Zimmerman, will also illustrate how the telescope's design reshaped our concept of how space exploration should be carried out, proving the necessity of having humans and robots work together in space in order for humanity to success-fully explore and colonize the solar system. 8pm IN THE MAIN LECTURE HALL Mr. Zimmerman will be available for book signing after his talk. Research and Technical Committees Get Busy Both of these committees are gearing up for ambitious programs some of which continue ongoing projects and some break new ground. Interested in restoring a unique 20-inch telescope, operating AAI's 14-inch Schmidt-Cassegrain telescope in the Jenny Jump State Forest via a graphic planetarium interface, obtaining official recognition for Sperry Observatory by the Minor Planet Center? Contact Mike Brown or Clif Ashcraft by using the links in the Club Activities | Standing Committees section of the website. 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 September 26 Team A October 3 Team B October 10 Team C October 17 Team D FRIDAYS AT SPERRY September 26, 2008 Ask Dr. Lew Dr. Lew October 3, 2008 TBA October 10, 2008 TBA 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) October 2008 finally gives us a chance to really appreciate the planet Venus. Although technically visible as an evening object since the end of Spring, Venus has not been observable against a totally dark background until this month. Far to the upper left of Venus, Jupiter dominates the southern sky as it has since the start of Summer. The two brightest planets start the month 60 degrees apart, and sedately approach each other at a pace of one degree per day. On the first evening of December, expect a magnificent wedding presided by the crescent Moon. If you are awake around 6am, you may notice that it is totally dark outside. Rather than cursing Daylight Saving Time, try looking up at an oddly familiar sky. The morning constellations of October are the same constellations you see on February evenings, just now without your gloves and parka. Orion is high in the south, inside the Great Winter Hexagon, and, Leo, the Lion, is rising in the east. During the fourth week of this month, the region below Leo is enhanced by the presence of the waning cres-cent Moon, a surprisingly dim Saturn, and a remarkably visible Mercury. Saturn's dimness is caused by our nearly edge-on view of its rings, while the easy visibility of Mercury is due to its elongation from the Sun occur-ring just five days before its northernmost latitude above the plane of Earth's orbit. Reaching an impressive magnitude -0.8, Mercury is five times as bright as Saturn during the last half of this month. Mars continues to be invisibly close to the Sun. The "Oddity of the Month" for October has to do with the phases of the Moon. Not only do they all fall on Tuesdays, but their dates are the four multiples of seven. Since the lunar period is 29.5 days, the same-day-of-the-week property may not be too surprising, but I couldn't find another occurrence since October 2005, start-ing with Monday the 3rd. Throwing in the seven times table gives us an event that may only happen four or five times a century. Of course, it is time-zone dependent, but this month it works from Universal Time westward almost all the way to Hawaii. NASA Science Outreach and Update by Ken Kremer Phoenix Landing on May 25 Phoenix is NASA's newest Mars science spacecraft and is on course and set to land in less than 2 weeks on the Martian north polar icy soil on May 25, above Mars' Arctic Circle. Using a powerful scoop located at the end of the robotic arm, Phoenix will dig into the hard as cement and ice-rich soil and analyze samples to study the history of water in the ice, search for evidence of climate cycles, monitor weather of the polar region and investigate whether the subsurface Martian polar environment has ever been favorable for microbial life. Phoenix Mars Lander scoops into icy soil (artist's rendition). Download image here: http://phoenix.lpl.arizona.edu/images/gallery/sm_139.jpg Phoenix Website: http://phoenix.lpl.arizona.edu/index.php New View of Doomed Moon Phobos NASA's Mars Reconnaissance Orbiter (MRO) took the stunning new color image of Phobos (next page) on March 23, 2008. Approximately 13.5 miles in diameter, Phobos is the larger of the two Martian moons. With less than one-thousandth the gravity of Earth, that's not enough gravity to pull the moon into a sphere, so it's oblong. Phobos was 4,200 miles away when the HiRISE camera on board took the photograph. The camera was able to see features as small as 65 feet across at that distance. "Phobos is of great interest because it may be rich in water ice and carbon-rich materials," according to Al-fred McEwen, HiRISE principal investigator at the Lunar and Planetary Laboratory at the University of Arizona, Tucson. Previous spacecraft, notably Mars Global Surveyor, have taken higher-resolution pictures of Phobos because they flew closer to the moon. "But the HiRISE images are higher quality, making the new data some of the best ever for Phobos," says Nathan Bridges, HiRISE team member at NASA's Jet Propulsion Laboratory in Pasadena, California. "These new images will help constrain the origin and evolution of this moon." Phobos orbits about 3500 miles above the Martian surface. The moon is doomed because gravity is pulling it down, and stresses will likely shatter it in about 100 million years to form a ring of decaying debris around Mars. Phobos from MRO: Download medium resolution version of this new image here http://mars.jpl.nasa.gov/mro/gallery/press/20080409b/PIA10368_br2.jpg Send Your Name to the Moon and Space LRO: NASA invites people of all ages to join the lunar exploration journey with an opportunity to send their names to the Moon aboard the Lunar Reconnaissance Orbiter, or LRO, spacecraft. LRO is being built at the NASA Goddard Spaceflight Center in Maryland. The Send Your Name to the Moon Web site enables everyone to participate in the lunar adventure and to place their names in orbit around the Moon for years to come. Par- ticipants can submit their information, print a certificate, and have their name entered into a database. The database will be placed on a microchip that will be integrated onto the spacecraft. The deadline for submitting names is June 27, 2008. Website: http://www.nasa.gov/mission_pages/LRO/main/index.html Kepler: NASA has announced an opportunity for anyone to submit their name to be included on a DVD that will be rocketed into space as part of NASA's Kepler Mission, scheduled to launch in February 2009 from NASA's Kennedy Space Center, Florida. The goal of this mission is to discover the first known Earth-like plan-ets beyond our solar system. Name in Space is an international activity associated with the International Year of Astronomy 2009 in recognition of the 400th anniversary of Johannes Kepler's publication of his first two laws of planetary motion. The deadline for submissions is November 1, 2008. Website: http://kepler.nasa.gov View from STS-123 Mission to the International Space Station (ISS): The next Space Shuttle mission, STS 124, is set to blast off with a 7-person crew on May 31, and deliver the giant Japanese Kibo pressurized science module to the ISS. Kibo will be the largest lab on the Space Station and it will be attached to the Harmony module. Farewell View of the ISS through the window of Shuttle Endeavour as it undocked on March 24, 2008: http://www.nasa.gov/externalflash/123_gallery/hi- resjpgs/28.jpg Astronomy Outreach Gloucester County College (GCC): Sewell, NJ, April 23. GCC "On Mars" in 3-D: At the kind invitation of GCC student Dan McCormick (and fellow member of the Rit-tenhouse Astronomical Society in Philadelphia), I was privileged to present a lecture titled "Exploring Mars (and Asteroids), the Search for Life, and a Journey in 3-D" to an enthusiastic crowd as the first speaker at the GCC Astronomy club. Photo: Dan McCormick GCC Astronomy Club Officers and Ken Kremer after the Mars Lecture: Newspaper announcements appeared in the Philadelphia Inquirer and Gloucester County Times which broadened the audience to members of the general public and fellow amateur astronomers from the south jersey area. Thanks to Dan (holding the RAT science drill) and the GCC staff ! Details here: http://www.gccnj.edu/general_information/ken_kremer.cfm Washington Crossing Nature Center: Titusville, NJ, April 12 The crowd enjoys the Solar System in 3-D via projected images and giant 3-D display posters at my talk on "Mars, Saturn, Asteroids and Beyond". Learn more and hear a Phoenix update at my UACNJ talk on Saturday, June 28 (details below). Please contact me for more info or science outreach presentations by email. My upcoming Astronomy talks include: United Astronomy Clubs of New Jersey (UACNJ) at Jenny Jump Observatory/Park: Hope, NJ, June 28, Sat, 8 PM. "Twin Robots Exploring Mars (in 3-D)" . Website: http://www.uacnj.org/Stella Della Valley Star Party and Bucks Mont Astronomical Association (BMAA): Ottsville, PA, Oct 25, Sat. "Launching DAWN to Asteroids: From Behind the Scenes at Kennedy Space Center". Dr. Ken Kremer Email: kremerken@yahoo.com NASA JPL Solar System Ambassador