November 2008 Volume 15 Number 5 Page 1

Star Gazer News

Newsletter of the Delmarva Stargazers www.delmarvastargazers.org

Upcoming Events: Meeting ! Nov. 4th 7PM Mallard Lodge

From the President….Our No Frills Star Party was a wash-out and was cancelled. However we are having our first (I think our first?) make-up star party on October 24/25th. This idea was brought up by a few of our members and is a nice gesture to all the folks who pre-registered for the No Frills and were disappointed. Don Surles has suggested we spice-up the Spring 2009 Star-Gaze Star Party. Don has many good ideas to bring a little excitement back to our star parties. Thanks Don! We received an official thank you for the folks who did the Adkins Arboretum outreach – Jerry et al.,

Many thanks for providing the highlight for the Arboretum’s Magic in the Meadow. Everyone has raved about the stargazing. And now Arboretum Trustee Jim Campbell seems to have adopted a new mission since he was so taken to learn that a night sky still exists at Adkins Arboretum. Obviously a very worth cause. Painful to learn how many people can never see the night sky. We can’t take this for granted. We hope you will accept our invitation to invite you back next year. We’ll be in touch. Ellie Altman Executive Director Adkins Arboretum

Another job well done, Big thanks to the gazers and spouses who helped out. This outreach has also generated some interest in saving the dark skies of TSP. It would be great to see the light domes around TSP diminished. Our November meeting is on election day, I hope everyone can get to vote and attend the meeting. We have a guest pres-entation by Bill Hartung’s daughter Katie. See you at the meeting. Tim

A History of Thanksgiving in the USA Don Surles Spaniards (1565-1598) Although all of us have been educated to believe the first Thanksgiving occurred in Plymouth, Mass, in 1621 by the Pilgrims and Indians, the first recorded Thanksgiving ceremony was on September 8, 1565 in what is now Saint Augustine, Florida. It seems about six hundred Spaniard settlers under the leadership of Pedro Menéndez de Avilés landed at what would be-come the city of St. Augustine and immediately held a Mass of Thanksgiving for their safe delivery to the New World. This Mass was followed by a feast and celebration. The La Florida colony did later become part of the United States, and thus can be classified as the First Thanksgiving. Also, the city of El Paso, Texas, has been said to be the site of the first Thanksgiving to be held in what is now known as the United States. And like the St. Augustine celebration, the El Paso festival was not a harvest festival. Records show that the Spaniard Don Juan de Oñate ordered his expedition party to rest and they conducted a mass in celebration of thanksgiving on April 30, 1598. The Virginia Colony (1619) On December 4, 1619, a party of 38 English settlers arrived at Berkeley Hundred which com-prised about eight thousand acres on the north bank of the James River near Herring Creek in an area then known as Charles City about 20 miles upstream from Jamestown, where the first permanent settlement of the Colony of Virginia had been established on May 14, 1607. The group's charter required that the day of arrival be observed yearly as a "day of thanksgiving" to God. On that first day, Captain John Woodleaf held the service of thanksgiving. As quoted from the section of the Charter of Berkeley Hundred specifying the thanksgiving service: "We ordaine that the day of our ship’s arrival at the place assigned for plantation in the land of Virginia shall be yearly and perpetually kept holy as a day of thanksgiving to Almighty God."[ An unprovoked assassination of an important local Indian Chief in 1622 provoked the Indian Massacre of 1622, and nine of the settlers at Berkeley Hundred were killed, as well as about a third of the entire population of the Jamestown Virginia Colony 20 miles downstream. The Berkeley Hundred site and other outlying locations were abandoned as the colonists withdrew to Jamestown and other more secure points. Berkeley Plantation (the new name for Berkeley Hundred) and part of the James River Plantations and Colonial Williamsburg tourist destination) continues to be the site of an annual Thanksgiving event to this day. The Pilgrims at Plymouth - 1621 Thanksgiving The Pilgrims arrived at Plymouth Rock, MA, in mid-November 1620. The 110 Pilgrims set about constructing housing, ie, shelters, to protect themselves from the approaching severe winter. The winter was espe-cially harsh and less than 50 of the settlers survived. In March 1621, a man named Samoset, a Patuxet Native American who re-sided with the Wampanoag tribe, walked into the settlement and greeted the settlers in English. Later, he returned with another In-dian named Squanto who taught the Pilgrims how to catch eel and grow corn and served as an interpreter for them (Squanto had learned English as a slave in Europe and travels in England). Without Squanto's help the Pilgrims might not have survived in the New World. There is still controversy about what kind of relationship Native Americans and Europeans might truly have had because a

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smallpox plague killed 90-95% of the local Native American population just prior to the actual arrival of the Pilgrims in 1620. The set-tlers who later came to be called the "Pilgrims" set apart a day to celebrate at Plymouth immediately after their first harvest, in 1621. At the time, this was not regarded as a Thanksgiving observance; harvest festivals existed in both English and Wampanoag tradition. Several American colonists have personal accounts of the 1621 feast in Plymouth, Massachusetts: William Bradford, in Of Plymouth Plantation: “They began now to gather in the small harvest they had, and to fit up their house and dwelling against winter, being all well recovered in health and strength and had all things in good plenty. For as some were thus employed in affairs abroad, others were exercised in fishing, about cod and bass and other fish, of which they took good store, of which every family had their portion. All the summer there was no want; and now began to come in store of fowl, as winter ap-proached, of which this place did abound when they came first (but afterward decreased by degrees). And besides waterfowl there was great store of wild turkeys, of which they took many, besides venison, etc. Besides, they had about a peck of meal a week to a person, or now since harvest, Indian corn to that proportion. Which made many afterwards write so largely of their plenty here to their friends in England, which were not feigned by true reports.” Edward Winslow, in Mourt's Relation: “Our harvest being gotten in, our governor sent four men on fowling, that so we might after a special manner rejoice together after we had gathered the fruits of our labor. They four in one day killed as much fowl as, with a little help beside, served the company almost a week. At which time, amongst other recreations, we exercised our arms, many of the Indians coming amongst us, and among the rest their greatest king Massasoit, with some ninety men, whom for three days we enter-tained and feasted, and they went out and killed five deer, which we brought to the plantation and bestowed on our governor, and upon the captain and others. And although it be not always so plentiful as it was at this time with us, yet by the goodness of God, we are so far from want that we often wish you partakers of our plenty”. The mention of Massasoit's ninety men in the Winslow account is of interest, as the number of Indians present, not men-tioned in most accounts, would have greatly outnumbered the fifty surviving Englishmen. The two preceding passages are the only records of the event, but historians presume that both the Indians and Pilgrims were exposed to unfamiliar forms of celebration. What is clear is that Massasoit's people had no interest in aggression, but rather sought to prosper from the newcomers. Following a drought, prayers for rain, and a subsequent rain shower in late 1623, the Pilgrims did hold a true Thanksgiving. Irregular Thanksgivings continued after favorable events…and days of fasting after unfavorable ones. In the Plymouth tradition, a thanksgiving day was a church observance, rather than a feast day. Gradually, an annual Thanksgiving after the harvest season developed in the mid-17th century. This did not occur on any set day or necessarily on the same day in different colonies in America. The Massachusetts Bay Colony (consisting mainly of Puritan Christians) celebrated Thanksgiving for the first time in 1630, and frequently thereafter until about 1680, when it became an annual festival in that colony; and Connecticut as early as 1639 and annually after 1647, except in 1675. The Dutch in New Netherland (NY) appointed a day for giving thanks in 1644 and occasionally thereafter. Charlestown, Massachusetts held it’s first recorded Thanksgiving observance June 29, 1671 by proclamation of the town's governing council. During the early18th century individual colonies commonly observed days of thanksgiving throughout each year. We might not recognize a traditional Thanksgiving Day from that period, as it was not a day marked by plentiful food and drink as is today's cus-tom, but rather a day set aside for prayer and fasting. Later in the 1700s individual colonies would periodically designate a day of thanksgiving in honor of a military victory, an adoption of a state constitution or an exceptionally bountiful crop. The Revolutionary War to Nationhood (1770 – 1780) During the American Revolutionary War the Continental Congress ap-pointed one or more thanksgiving days each year, each time recommending to the executives of the various states the observance of these days in their states. The First National Proclamation of Thanksgiving was given by the Continental Congress in 1777. George Washington, leader of the revolutionary forces in the American Revolutionary War, proclaimed a Thanksgiving in December 1777 as a victory celebration honoring the defeat of the British at Saratoga. Thanksgiving Proclamations in the First Thirty Years of Nationhood As President, on October 3, 1789, George Washing-ton issued a proclamation and created the first Thanksgiving Day designated by the national government of the United States of

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How to Join the Delmarva Stargazers: Anyone with an interest in any aspect of astronomy is welcome NAME________________________________________________________________________________________ ADDRESS_____________________________________________________________________________________ CITY, STATE & ZIP______________________________________________________________________________ E-MAIL ADDRESS (If any)_________________________________________________________________________ Do you need the newsletter snail mailed to you (Y/N)?___________________________________________________ Please attach a check for $15 made payable to Delmarva Stargazers and mail to Kathy Sheldon, 20985 Fleatown Rd, Lincoln, DE 19960. Call club President Tim Milligan at 410-841-9853 for more information.

The Solar System in November Mercury is still visible in morning twilight in early Nov. as it slips behind Sol to a superior conjunction on the 25th. Venus brightens to mag –4.2 this month, setting after Sol. Mars is lost in solar glare this month. Jupiter is visible in evening sky and joins Venus at the end of the month Saturn rises after midnight, and by mid-month, the rings are only 1.5° from ‘edge-on’. Uranus is in Aquarius all year. It is at opposition, and the brightest for the year. “The experts” say you can see Uranus with your unaided eyes from a good site. Neptune is 1° S of Luna on the 6th . The minor planet Pluto is above the ‘Teapot’ handle. As always (hopefully), you can find Terra by looking under your feet. The Leonids meteor shower peaks on the 17th but the meteor/hr rate this year is only 15, still fun to watch.

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Your 2007-2008 Officers Office Officer Phone President Tim Milligan 410-841-9853 President-elect Don Surles 302-653-9445 Secretary Michael Lecuyer 302-284-3734 Treasurer Kathy Sheldon 302-422-4695 Past President Tom Pomponio 302-736-0157 Editor Pj Riley 302-738-5366

An Antique Gregorian Telescope Speculum Mirror Restoration

Michael Lecuyer This is about the resurfacing and polishing of the primary speculum mirror for an antique Gregorian telescope from the 1700’s making it about 300 years old. The job dropped into my lap when I suggested to Richard Elsworthy that I had made some glass tele-scope mirrors a long time ago and I would like to work on a metal mirror someday. He said there was an antique reflecting telescope with a bad metal mir-ror that a dealer wanted fixed. “Ok,” I said. The last time I’d ground a mirror was about 30 years ago.

In March of 2008 the Stargazers held their Eighth Mid-Atlantic Mirror Making Seminar and I hung out doing odd jobs to help out. I learned about new grinding grits (White Aluminum Oxide – WAO) and saw first hand how fast Cerium Oxide could fully polish a mirror - big changes from alundum, emery and rouge of my youth. Dave Groski connected me to an expert in Speculum, Matt Considine, who had cast speculum mirrors. This all seemed to be going in the right direction. I ordered my assortment of grits, pitch and polish from GotGrit.com (which even rushed a deliv-ery of 9µ aluminum oxide grit when the 5µ was un-available). Then I was off to work on the telescope. The mirror is 60mm in diameter with a focal length of about 244mm (9 5/8”) and has a conical central hole for the light to pass through to the eye-piece. The Gregorian design is the converse of the

Cassegrain. The Gregorian system uses a concave secondary mirror outside the primary’s focus while the Cassegrain uses a convex secondary inside the primary’s focus and the mathe-matics describing the systems is identical with a few sign changes. The Gregorian’s design became popular since the view is a correct upright image suitable for terrestrial and astro-nomical use. Typically the secondary was moved to change the focus using the long rod on the top of the telescope. It was clear there was a lot wrong with the primary mir-ror besides tarnish. Someone had deliberately driven a chisel (there is a very clear mark) into the bottom of the mirror in an effort to break it. They failed to break it but it was cracked from the edge to the central hole. This was no accident. The surface appeared to have mechanical turning marks on it and was deeply pitted from the sand casting. There is a picture of the mirror with fine, straight crack and a micrograph of the existing scratched and pitted surface. It looked like it was never made to reflect an image. Just how did a telescope that didn’t work at all survive for 300 years?

Two tools were made from 60mm hexagonal tiles from a tile mesh were embedded in dental stone. One tool is called the ‘bruiser’ (described in an article by John Mudge in 1777) which is used to shape tools to be used on the mirror. The bruiser is ground to the curvature of the speculum mirror. In my case the bruiser and tool started flat and were hogged out on top of a lawn tractor outdoors. Smoothing to polishing took place indoors on an improvised optical lathe. We used the ‘rocking’ test to get the tool to match the speculum mirror and then the ‘Sharpie’ test to confirm the tool and mirror matched. Please see the photo of how rough grinding is done in the wild. (see picture on top left of pg. 4) Fine grinding and smoothing went will up the point of the 15µ WAO. The 9µ WAO created scratches so these were ground out with the 15µWAO. The polishing lap was made from hard pitch on a dental stone tool cast on the finely ground mir-ror. The pitch was poured onto the tool and then pressed on the

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mirror with ¼” metal mesh using a ten pound weight in the back of my black pickup truck bed in the sun until the pitch yielded. Polishing with cerium oxide took 5 hours. For those who haven’t ground or polished metal mirrors the metal residue in the rinsing bowl coats everything with a nasty grey and greasy film. Jean Texereau’s book ‘How to Make a Tele-scope’ pointed out that small optics (less than three inches) should be done on an optical lathe that turns at 15 RPM or less and used seated. The ATM Book #2 implicitly confirmed this in their refractor section. Richard happened to have a surplussed ‘shape fol-lower’ machine that had a slow motor and pulley sys-tem that turned at 4 rpm that turned out to be just right. All the regular strokes used in fine grinding and polishing were used along with constant turning of the bottom element, tool or mirror. In the end we were unable to figure the mir-ror. The Ronchi test showed that the mirror was a perfect sphere with a turned down edge of about 2mm and the central hole was a little turned up – but less that the secondary’s diameter. The decision to end further work was made after the mirrors surface was examined under a microscope. The pits men-tioned in the beginning of the article were found to be emitting tiny particles and were the source of the scratching. It may be that these deep pits harbored some of the grit although a photograph taken before work started showed the pits emitting debris when

Richard had done an initial cleaning of the mirror surface. There is a mi-crograph of a small part of the mirror after polishing. Note some pits have originated a few scratches.

The mirror was tested in the telescope and found to produce an acceptable star image when turned on Vega. The brass alt-azimuth stand became fairly loose at 60° altitude so I only got a brief glimpse of a poorly focused Saturn. Its main purpose was to be a spotting scope and it showed good de-tailed within washed out images. The black paint on the inside of the scope was shiny at grazing angles. We improved the im-age with a paper baffle tube through the primary mirror similar those used in modern Schmidt-Cassegrain telescopes. Unfortu-nately that technology wasn’t used 300 years ago so better paint will have to cure the problem. In conclusion working with speculum mirrors is almost the same as working with glass. The tools and materials work the same way but metal tends to scratch much easier and a light touch is necessary. The brittleness of speculum is proba-bly worth concern although the existing crack did not cause any problems. It didn’t even appear to cause any imaging problems or warping of the mirror. And like riding a bicycle you never for-get how to grind a mirror. I would like to thank my friend Rich-ard Elsworthy for building the many tools we used in the proc-ess. Richard also sent a recent hand held photo of the moon through the telescope.

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Magazine Subscriptions As a paid member of DMSG, you can sign up/renew your S&T or Astronomy mags through the club for a discount over private rate. S&T, reg. $42.95, is $32.95 thru DMSG, Astronomy, reg. $44, is $34. See Michael Lecuyer for details.

The Chemical Weather Report “Sunny tomorrow with highs in the mid-70s. There’s going to be some carbon monoxide blowing in from forest fires, and all that sunshine is predicted to bring a surge in ground-level ozone by after-noon. Old and young people and anyone with lung conditions are advised to stay indoors between 3 and 5 p.m.” Whoever heard of a weather report like that? Get used to it. Weather reports of the future are going to tell you a lot more about the atmosphere than just how warm and rainy it is. In the same way that satellite observations of Earth revolutionized basic weather forecasting in the 1970s and 80s, satellite tracking of air pollution is about to revolutionize the forecasting of air quality. Such forecasts could help people plan around high levels of ground-level ozone—a dangerous lung irritant—just as they now plan around bad storms. “The phrase that people have used is chemical weather forecasting,” says Kevin Bowman of NASA’s Jet Propul-sion Laboratory. Bowman is a senior member of the technical staff for the Tropospheric Emission Spectrometer, one of four scientific sensors on NASA’s Aura satellite. Aura and other NASA satellites track pollution in the same way that astronomers know the chemical composition of stars and distant planetary atmospheres: using spectrometry. By breaking the light from a planet or star into its spec-trum of colors, scientists can read off the atmosphere’s gases by looking at the “fingerprint” of wavelengths absorbed or emitted by those chemicals. From Earth orbit, pollution-watching satellites use this trick to measure trace gases such as carbon monoxide, nitrogen oxide, and ozone. However, as Bowman explains, “Polar sun-synchronous satellites such as Aura are limited at best to two over-passes per day.” A recent report by the National Research Council recommends putting a pollution-watching satellite into geosynchronous orbit—a special very high-altitude orbit above the equator in which satellites make only one orbit per day, thus seeming to hover over the same spot on the equator below. There, this new satellite, called GEOCAPE (Geostationary Coastal and Air Pollution Events), would give scientists a continuous eye in the sky, allowing them to pre-dict daily pollution levels just as meteorologists predict storms. “NASA is beginning to investigate what it would take to build an instrument like this,” Bowman says. Such a chemical weather satellite could be in orbit as soon as 2013, according to the NRC report. Weather forecasts might never be the same. Learn more about the Tropospheric Emission Spectrometer at tes.jpl.nasa.gov. Kids can learn some elementary smog chemistry while making “Gummy Greenhouse Gases” out of gumdrops at space-place.nasa.gov/en/kids/tes/gumdrops. This article was provided by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

Example of visualization of data from the Tropo-spheric Emission Spectrometer. These frames are from an animation that steps through transects of the atmosphere profiling vertical ozone and carbon mon-oxide concentrations, combining all tracks of the Aura satellite during a given two week period.

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America. George Washington again proclaimed a Thanksgiving in 1795. President John Adams declared Thanksgivings in 1798 and 1799. No Thanksgiving proclamations were issued by Thomas Jefferson but James Madison renewed the tradition in 1814, in re-sponse to resolutions of Congress, at the close of the War of 1812. Madison also declared the holiday twice in 1815; however, none of these were celebrated in autumn. Governor John Brooks of Massachusetts appointed Thursday, November 28 to be "observed throughout that State as a day of Thanksgiving. A thanksgiving day was annually appointed by the governor of New York beginning in 1817. In some of the Southern states there was resistance to the observance of such a day on the grounds that it was a relic of Puritan bigotry, but by 1858 proclamations appointing a day of thanksgiving were issued by the governors of 25 states and two territo-ries. Lincoln and the Civil War (1860’s) In the middle of the American Civil War, President Abraham Lincoln, prompted by a series of editorials written by Sarah Josepha Hale, proclaimed a national Thanksgiving Day, to be celebrated on the final Thursday in Novem-ber 1863. Since 1863, Thanksgiving has been observed annually in the United States. A tidbit of information on Sarah Josepha Hale…she was the author of the childrens’s poem, “Mary Had a Little Lamb”. 1939 to 1940 Abraham Lincoln's successors as president followed his example of annually declaring the final Thursday in Novem-ber to be Thanksgiving. But in 1939, President Franklin D. Roosevelt declared that Thanksgiving would be the fourth Thursday of November rather than the last. With the country still in the midst of The Great Depression, Roosevelt thought this would give mer-chants a longer period to sell goods before Christmas. Increasing profits and spending during this period, Roosevelt hoped, would aid bringing the country out of the Depression. At the time, advertising goods for Christmas before Thanksgiving was considered inappropriate. However, since a presiden-tial declaration of Thanksgiving Day was not legally binding, only 23 states went along with Roosevelt's recommendation, and 22 did not. Other states, like Texas, could not decide and took both weeks as government holidays. 1941 to present The U.S. Congress in 1941 split the difference and passed a bill requiring that Thanksgiving be observed annually on the fourth Thursday of November, which was sometimes the last Thursday and sometimes (less frequently) the next to last. On December 26 of that year President Roosevelt signed this bill, for the first time making the date of Thanksgiving a matter of federal law. Since 1947, and possibly earlier, the National Turkey Federation has presented the President of the United States with one live turkey and two dressed turkeys, in a ceremony known as the National Thanksgiving Turkey Presentation. The live turkey is par-doned and lives out the rest of its days on a peaceful farm. While it is commonly held that this pardoning tradition began with Harry Truman in 1947, the Truman Library has been unable to find any evidence for this. The earliest on record is with George H. W. Bush in 1989. Still others claim that the tradition dates back to Abraham Lincoln pardoning his son's pet turkey. Both stories have been quoted in more recent presidential speeches. In more recent years, two turkeys have been selected for the pardoning, in case the original turkey becomes unavailable for presidential pardoning. Since 2003 the public has been invited to vote for the two turkeys' names. They were named Stars and Stripes in 2003 and 2004's turkeys were called Biscuit and Gravy. In 2005 the public decided on Marshmallow and Yam, in 2006 it was Flyer and Fryer, and in 2007 on May and Flower. Since 2005, the two turkeys have been flown first class on United Airlines from Washing-ton, D.C. to the Los Angeles area where they become the Grand Marshals of Disneyland's annual Thanksgiving Day parade down Main Street. The two turkeys then live out the rest of their relatively short lives in Disneyland's Frontierland ranch. Foods of the season U.S. tradition compares the holiday with a meal held in 1621 by the Wampanoag and the Pilgrims who set-tled in Plymouth, Massachusetts. This element continues in modern times with the Thanksgiving dinner, often featuring turkey, playing a large role in the celebration of Thanksgiving. Some of the details of the American Thanksgiving story are myths that developed in the 1890s and early 1900s as part of the effort to forge a common national identity in the aftermath of the Civil War and in the melting pot of new immigrants. Traditional Thanksgiving Dinner In the United States, certain kinds of food are traditionally served at Thanksgiving meals. First and foremost, turkey is usually the featured item on any Thanksgiving feast table (so much so that Thanksgiving is sometimes referred to as "Turkey Day"). Stuffing, mashed potatoes with gravy, sweet potatoes, cranberry sauce, corn (maize), other fall vegetables, and pumpkin pie are commonly associated with Thanksgiving dinner. All of these primary dishes are actually native to the Americas or were introduced as a new food source to the Europeans when they arrived.

A Telescope Repair Tip Michael Lecuyer Lost your eyepiece cap on your Orion RACI (Right Angle Correct Image) finder? You can’t get one from Orion – their replacement caps are too large. Go out and buy a nice 750 ml bottle of Puerto Rican Rum. Sample it frequently. Ummmm, good! All gone? Great! The bottle’s screw cap fits the .965" Orion finder eyepiece. Interesting eyepiece size, huh? And you thought that 60mm1000X department store telescope was a bad memory! You can use the screw cap as it stands but it'll get a really firm grip on the eyepiece and will probably unthread it when you try to remove the cap. Find some scissors and gently scrape a little plastic off the threads (the flat edge of the scissors removes the threads evenly). It’s a close fit so it doesn't take much scraping to overdo it. Remove too much thread and you'll have to buy another bottle of rum - bother! (Ed. Note: if you’re under 21, have your parents buy and sample the rum)

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Moondark for November: Catching Mercury Doug Miller In the past few weeks, early risers have had a great opportunity to catch the planet Mercury. Beginning about an hour before dawn, the closest planet to the Sun is visible as the morning star in the eastern twilight, the only bright “star” in that area of the sky. Well above it, though not nearly as bright are Regulus (representing the heart of Leo the Lion) and Saturn. As dawn approaches, Mercury disappears quickly into the rapidly brightening sky. Mercury is elusive not because it is dim, but because you have to look at just the right time and in just the right part of the sky. Exactly where and when to look de-pend on orbital geometry, your geography and the angle the ecliptic makes with the ho-rizon. On 22 October, Mercury was at western greatest elongation, its maximum appar-ent distance west of the Sun as seen from Earth. The ecliptic trends southward from Gemini, crossing the equator in Virgo, and that dip angles the ecliptic roughly perpen-dicular to our horizon around sunrise. Under these conditions, Mercury is as far from the Sun as possible, at an angle well above our horizon, optimal conditions for seeing Mercury. In fact, this apparition is one of the most favorable for the whole year. At mid northern latitudes, Mercury is typi-cally at its best as a morning star in the fall, while the spring favors Mercury as an eve-ning star. This situation is reversed for observers in the southern hemisphere. Some-what surprisingly, southern latitudes are overall better for viewing Mercury because of the planet's elliptical and inclined orbit (more so than all other planets except Pluto's) as well as Earth's tilted axis. Even if you have a late commute from work, you won’t have to wait long to catch sight of Mercury. In late November, Mercury passes through superior conjunction, almost directly in line with the Earth and Sun on the far side. Recall that transits of Mer-cury occur only in November as well as six months later in May. Mercury then climbs to become an evening star as 2009 begins, swinging to its greatest eastern elongation in mid January. This time look before the planet sets about an hour after sunset, for which you’ll need a clear view of a low southwestern horizon on the commute home. Mercury will again be an evening star, somewhat more favorably placed on its next trip around the Sun in late April and May. If clouds block the view or if you can’t face the nighttime chill, you can always grab a laptop and browse Mercury from the comfort of a warm chair. NASA’s MESSEN-GER [MErcury Surface, Space ENvironment, and GEochemistry and Ranging) probe has returned stunning images of a cratered planet. Launched in 2004, MESSENGER made its first flyby early in 2008 and its second this past month on 6 October. After a third flyby next year, MESSENGER will settle into orbit in 2011 for a planned, year-long mission of observations and experiments. Remarkably, this is only the second space-craft to journey to Mercury: Mariner 10 made three passes in 1974-5. Even partway through MESSENGER’s mission, unexplored regions of the planet have now or will be soon been imaged in unprecedented detail, and planetary scientists are poring over the images. Mercury is obviously battered by impacts like the Moon, yet it is visibly distinct. Mercury has no maria (large and dark, flat and relatively uncratered lava basins) or dis-tinct mountain ranges, although volcanoes ring impact basins. On the other hand, both have fresh-looking impact craters and ejecta rays, compare our Moon's Tycho with Mer-cury's Kuiper, both presenting a navel orange appearance. Compare these two rugged bodies for yourself: what differences and similarities do you see? The crescent Moon slipped past Mercury during the last weekend of October and for the rest of the year, Venus and Jupiter stand as evening stars. Watch how this pair draws to within 2 degrees by the end of November. The crescent Moon will sweep past the pair on the first of December. And don’t miss this treat for the New Year: the crescent Moon again joins the evening stars, Venus and Jupiter and this time, Mercury, in a lovely celestial conjunction for the drive home around the holidays. For more information on celestial events and sights, see Guy Ottewell’s Astronomical Calendar for 2008 and 2009 as well as Francis Reddy and Greg Walz-Chojnaki’s Celestial Delights. Moondark is written by Douglas C. Miller, published at the Moondark web site, and printed in the Delmarva Star Gazers' Star Gazer News. This document was last revised on 25 October 2008. Text on this web page is free for non-commercial use with attribution under a Creative Commons Attribution-Non-commercial 3.0 License. Ask Doug about other uses.

The Moon ...

or Mercury?

Source: NASA's MESSENGER Mis-sion to Mercury site