National Capital Astronomers, Inc.

Volume 56, Number 3

Phone: 301/565-3709

ISSN 0898-7548

Roving and Revolving Over the Red Planetby James R. Zimbelman

The next meeting of the National Capi-tal Astronomers will be held on Satur-day, November 1 at 7:30 P.M., in theLippsett Auditorium on the main floorof the Clinical Center (Building 10) atthe National Institutes of Health (NIH).James R. Zimbelman of Center for Earthand Planetary Studies will speak on"Roving and Revolving Over the RedPlanet." The speaker sent the followingabstract and biography.

The dramatic landing of Mars Path-finder on July 4 brought Mars back tothe attention of the world. After anabsence of 15 years (since we lost con-tact with Viking lander 1), we were backon the Martian surface. The mobility ofthe Sojourner rover has brought a newdimension to exploring Mars, and thislecture will summarize some of the ma-jor activities and preliminary resultsobtained by Pathfinder to date. On Sept.11, Mars Global Surveyor (MGS) wentinto orbit around Mars, becoming the----------------------------

a Ph.D. in Geology, Arizona State Uni-versity, Tempe, AZ. From 1984 to1988, he was a post-doctoral fellow andstaff scientist at the Lunar and PlanetaryInsitute in Houston, TX. From 1988 tothe present, he has worked as a geologistat the Center for Earth Planetary Studiesat the National Air and Space Museumat the Smithsoniam Institution in Wash-ington, DC. Dr. Zimbelman's researchinterests are geologic mapping and re-mote sensing analysis of Mars and Ve-nus, computer simulations oflava flowson the terrestrial planets, and sand trans-port in the Mojave Desert of California.During graduate school, he was a mem-ber of the Science Flight Team for theViking orbitor mission to Mars on theInfrared Thermal Mapper experiment(Hugh Keiffer, P.L). He is currently theChairman of the Planetary Geology Di-vision of the Geological Society ofAmerica. 0

first U.S. orbiter at the Red Planet sinceViking Orbiter 2 arrived in 1976. Thespacecraft will adjust its orbit usingaerobraking passes through the upperatmosphere of Mars for several months,but prior to the aerobraking oneperiapsis pass was devoted to the sci-ence instruments. The first results fromthe MGS science teams were presentedat a science conference on October 2,and these results will also be summa-rized in the lecture. Both Pathfinder andMGS represent a resurgence of attentionon Mars by NASA, and the lecture willclose with some of the plans for otherspacecraft that are scheduled to belaunched during the next several years.

James Zimbelman received a B.A.in physics and Mathematics fromNorthwest Nazarene College, Nampa,ID in 1976. He received his M.S. inGeophysics and Space Physics fromU.CLA in 1978. In 1984, he received

The 1997 September NCA meeting fea-tured the presentation "Extra SolarPlanets" given by Alan Boss ofCarnegie Institution of Washington,Department of Terrestrial Magnetism.Extra solar planets are those which havebeen discovered orbiting around stars.Most of these stars are similar in size andtemperature to our sun, a G2 main se-quence dwarf.

For the first part of his presentation,Dr. Boss discussed methods by whichthe planets are detected. These methodsfall under two categories, direct andindirect. By direct, it is meant that theplanet itself, is observed as an objectseparate from the star it orbits. To do so,the light of the star must be masked by adevice (a coronagraph) because theplanet only reflects light from the star

and, therefore, its faint brightness isoverwhelmed by the star's light. Cur-rent technology does not permit this

Next GenerationSpace Telescope

The review of Seeing the First ObjectsWith the Next Generation Space Tele-scope was not available at press time. Itwill be published in the next Newsletter.

Cllfendizr of fMontnlj ~f)ents

Saturday, November 1, 5:30 PM-Dinner with thespeaker and other NCA members at the Faryab AfghanRestaurant, 4917 Cordell, Bethesda, MD. See map anddescription on back page.

Saturday, November 1,7:30 PM-NCA meeting, willfeature James Zimbelman speaking on "Roving andRevolving Over the Red Planet." For directions, seemap and description on back page.

Mondays, November 3, 10, 17, and 24, 7:30 PM-Public nights at U.S. Naval Observatory (USNO), inNorthwest Washington, D.C. (off Massachusetts Av-enue). Includes orientation on USNO's mission,viewing of operating atomic clocks, and glimpsesthrough the finest optical telescopes in the Washing-ton-Baltimore region. Held regardless of cloud cover.Information: USNO Public Affairs Office, 202/762-1438. Home page: http://www.usno.navy.mil.

Tuesdays, November 4, 11, 18, and 25, 7:30 PM-Telescope making classes at Chevy Chase Commu-nity Center, Connecticut Avenue and McKinleyStreet, NW. Information: Jerry Schnall, 202/362-8872.

Fridays, November 7, 14, 21, and 28, 7:30 PM-Telescope making classes at American University,

because no existing telescope can re-solve the planet and star as two separateobjects. So far, all extra solar planetshave been detected only by indirectmeans.

Two indirect methods were dis-cussed. Earlier attempts to detect thepresence of a planet orbiting the starwere based on the wobble of its star'sposition caused by its motion around thestar-planet common center of mass(barycenter). From observations madebetween 1916 and 1963, Peter Van deKamp, at the Swarthmore College Ob-servatory, claimed the detection of suchmotion of Barnard's star. However,George Gatewood, using new data ob-

McKinley Hall Basement. Information: Jerry Schnall,202/362-8872.

Fridays, November 7, 21, and 28, 8:30 PM-Opennights with NCA's Celestron-14 telescope atRidgeview Observatory; near Alexandria, Virginia;6007 Ridgeview Drive (off Franconia Road betweenTelegraph Road and Rose Hill Drive). Information: BobBolster, 703/960-9126. Jupiter and Saturn are featured.

Saturday, November 8, 7:00 PM-"Exploring the Sky,"Rock Creek Park, near the Nature Center. Information:202/426-6829. This program will return in the spring.

During questionable weather, call the lOT A Hotline(Phone: 301/474-4945) for NCA meeting status. Theabsence of a cancellation notice on the Hotline means themeeting will take place.

See page 8 for more Washington area astronomicalevents. Other events too numerous to list in Star Dust~-listed in the publications Sky & Telescope, the Astro-nomical Calendar 1997, the Observer's Handbook1997, in numerous software packages, and other linksavailable on the NCA Home Page (see above for ad-dress). NCA members can purchase all these (and muchmore) at a discount. To join NCA, use membershipapplication on page 9.

tained with a different telescope, failedto duplicate Van de Kamp's results.Furthermore, John Hershey, also of theSwarthmore College Observatory, laterdiscovered that the "jump" which PeterVan de Kamp detected in Barnard'sstar's proper motion, resulted from therefurbishment of the telescope's opticsduring the observation period.

The technique which two Swissastronomers, Michel Mayor and DidierQueloz, observing at the HauteProvence Observatory in France em-ployed to detect the planet around 51Pegasi was based upon measuring thevelocity along the observer's line ofsight (the radial velocity) whichchanges periodically toward and awayfrom the observer. The position of the

spectral lines in the star light shift peri-odically toward the red end of the spec-trum (as the planet moves away from theobserver) and then toward the blue endof the spectrum (as the planet movestoward the observer). By means of theDoppler principle, the planet's orbitalvelocity is computed from the magni-tude of the spectral line shift. Mayor andQueloz measured a Doppler velocitymagnitude of 60 meters per second. Thevelocity curve was a sine curve between-60 and +60 mls with a period of 4.3days. Applying Kepler's laws to thedata shows that the mass of the planet ison the order of 0.46 times the mass ofJupiter and the planet's orbit is circular

PLANETS, Continued on page 3

with a distance from the star (the orbitalradius) of 0.05 times that of the averageEarth-Sun distance; that is, a distance of0.05 astronomical units (au). Therefore,this massive planet would lie well insideMercury's orbit if it were in an orbitaround our Sun. For comparison, Mer-cury has an orbit radius of 0.39 au and aperiod of 88 days.

This result was soon verified bytwo American astronomers, GeoffMarcy and Paul Butler, using the 120inch telescope of the Lick Observatory.That was followed by Marcy andButler's own detection of a planetaround another solar type star, 47 UrsaMajoris. That planet has an orbital pe-riod of 1,103 days (3 years, 7 days) anda mass of about 2 to 3 times that ofJupiter.

These planets revolve around mainsequence stars similar to our Sun. 51Peg has a spectral type G3, 47 UMa is aG3 star, and the Sun is a G2 star. How-ever, in 1992, Alexander Wolszczanand Dale Faril announced their discov-ery of two planets revolving around thepulsar PSR1257+12, a planet of 3.4Earth masses with an orbital period of66.6 days and a planet of 2.8 Earthmasses with a period of 98.2 days. In1994, Wolszczan announced that a thirdplanet exists in the PSR1257+12 sys-tem, an Earth-moon sized planet with aperiod of 25.3 days.

Two questions motivated a discus-sion of the theories of stellar and plan-etary formation: "How can a Jupiter-sized planet for so close to the parentstar?" and "What is the difference be-tween a brown dwarf and a largeplanet?"

Stars are formed when a cloud ofgas collapses around a cool, dense re-gion in the interstellar medium. Thecollapse starts slowly at first. As thespeed of the gas toward the center in-creases, the cloud may fragment intotwo or more components. Higher den-sity clouds heat up quickly. Fragmenta-tion will continue until the gas densityincreases to the extent that thermal pres-sure prevents further fragmentation.Two fragments orbiting around theircommon center of mass will form abinary star, usually with an ellipticalorbit with a high eccentricity. A star,produces its energy from the thermo-

nuclear fusion of hydrogen. Hydrogenfusion can only take place when there isenough mass - at least 0.08 solarmasses - to create the necessary tem-perature and pressure at the core. Jupiterhas a mass of 0.00 I solar masses; there-fore, the minimum stellar mass is about80 Jupiter masses. When a proto-stellarfragment has a mass less than 80 Jupitermasses, a brown dwarf is formed. Dr.Boss pointed out that the image ofGleise 229B, a brown dwarf orbiting ata distance from its companion, Gleise229A, is sufficient enough that it can beresolved.

Planets seem to be formed fromcircumstellar discs of rotating gas anddust resulting from the collapse of thestar. Dust grains settle in less than10,000 years and collide with eachother, eventually forming clumps. Theclumps accrete into 10 km sized proto-planetary objects within about 100,000years and terrestrial sized planets within100 million years. Jovian planets havelarge rocky cores which are for enoughfrom the hot star that they collect gassesand form thick envelopes. For a solar-type star, they must form no closer inthan about 5 times the Earth-Sun dis-tance (5 au) from the star. (Jupiter is 5.2au from the Sun.) Also, they must formsoon enough before the gas in the cir-cumstellar disc is driven off by the stel-lar wind. The rocky, or terrestrial, plan-ets are formed inside the 5 au limit.

If this process is correct, the ques-tion is "How can the Jupiter-sized planetaround 51 Pegasi form so close to thestar?". The answer to this, as Dr. Bossexplained, is that the planet may haveformed in the gas giant region and mi-grated inward toward the star. He pre-sented two mechanisms for the migra-tion. One mechanism involves a spiralstructure which develops in the plan-etary disc; the spiral arms pull the planetinward. The other mechanism involvesviscosity in the proto-planetary whichcauses some mass to move inward andother mass to move outward.

The resulting stellar system struc-ture is as follows. Brown dwarfs form in

a highly eccentric orbit if the stellarcompanion mass is greater than 5 Jupitermasses. If this mass is less than 5 Jupitermasses, a gas giant planet in a low ec-centric (close to circular) orbit isformed. Hot Jovian planets would mi-grate inward. The disc from which the51 Pegasi system was formed survivedlong enough for the planet to migrate into its current location. The disc nolonger acts on the planet which is now,apparently, in a stable orbit.

Future research into planetary sys-tems will require the ability to detect thepresence of Earth-sized planets and,hopefully, be able to separate the imageof large planets from their star. Thisrequires telescopes with greater sensi-tivity and resolving power than are cur-rently available. The 10 meter Kecktelescope on Mauna Kea in Hawaii willbe outfitted with 2 meter outrigger tele-scopes to form an interferometer whichwill be able to resolve two objectsspaced 10 micro-arc seconds apart.Also, a space interferometer is beingconsidered which will be placed in a5 auorbit around the Sun. This large orbit isrequired so that interferometer will beoutside the band of interplanetary dustwhich creates the zodiacal light. Theinterferometer, itself will consist of twotelescopes at the ends of a 75 meterboom The instrument will be sensitiveto infrared radiation with a wavelengtharound 10 microns so that it has a chanceof detecting the thermal radiation of aplanet close to a star.

Following the talk, Dr. Boss re-sponded to a question from the audiencewhich was "Can 51 Peg be an intrinsicvariable?". This question refers to theconjecture which tries to explain thevariation in the star's spectrum to be dueto a periodic expansion and contractionof its atmosphere rather than due to aperiodic motion caused by an orbitingplanet. Boss, reply was that the lumi-nosity (total power output) of the star isknown to be constant to 1/5,000. Aperiodic expansion and contractionwould cause the luminosity to vary aswell. 0

Don't throw this newsletter away. If you're finished with it,pass it on to someone else to read or recycle it. It's right forastronomy and the environment.

Images From Mars Pathfiner

• They are spatter from lava flows.• They are nodules brought up from the deepMartian interior by lava flows or pyroclasticeruptions.• They are concretions formed in sedimentaryrocks.• They came from ancient conglomerate rocks.The pebbles were rounded by water action andsubsequently lithified into conglomerate rocks.Lnter, the waters of catastrophic floodstransported the conglomerates and deposited themon the Ares flood plain. The pebbles were thenfreed from the rocks by weathering.• A combination of the above.

The Sojouner rover image of the "Cabbage Patch"shows small rounded objects on the surface that areabout 3-4 cm across. Some of these are withinexcavations, which are about 0.5 cm wide. Severalquestions arise about the pebbles: 1) Why are theyround? 2) Where did they comefrom? 3) What dothey mean? Geologists use Multiple WorkingHypotheses when attempting to explain observations.Some hypotheses that could account for the pebblesare:

• They were rounded during transport by waters orcatastrophic floods and deposited on the Ares Vallisflood plain.• They were rounded by wave action on an ancientMartian beach.• They were rounded by glacial transport.• They are glasses that were produced by meltingduring impact crate ring. The glass was first ejectedfrom the crater, then molded into spherical shapes ordrops as it traveled through the atmosphere, andfinally was deposited at the sites.

Pebbles are also seen in lander images, along with cobbles. For example, in thispicture, we see the same pebbles that were visible in the Sojouner rover image ofthe "Cabbage Patch". In addition, a cobble within the rock "Lnmb" (upper left)is apparent. This indicates that Lnmb may be a conglomerate (Lnmb is 0.32 m x0.15 m).

The composite image of the "RockGarden" shows the rocks "Shark" and"Half Dome" at upper and middle,respectively. Between these two largerocks is a smaller rock (about 0.20 m wide,0.10 m high, and 6.33 mfrom the Lander)that was observed close-up with theSojourner rover.

The composite image from thePathfinder lander shows the rock"Shark" at upper right (Shark isabout 0.69 m wide, 0.40 m high, and6.4 m from the lander). The rocklooks like a conglomerate in Sojounerrover images, but only the largeelements of its surface textures can beseen here. This demonstrates theusefulness of having a robot geologistable to examine rocks up close.

PEBBLES, COBBLES, AND SOCKETS

SHARK - SOL 71

This Rover image of "Shark" (upper left center), "Half Dome" (upper right), and a small rock (rightforeground) reveal textures and structures not visible in lander camera images. These rocks areinterpreted as conglomerates because their surfaces have rounded protrusions up to sevearl centimeters insize. It is suggested that the protrusions are pebbles and granules.

GreetingsAn open letter from

Geoffrey Lane

It is with great sadness in my heart that I must inform you and all the members, friends, and associates of the NationalCapital Astronomers that I am moving to Hawaii and our program "Comet Crashers" will become a fading memory.

We at the nature center appreciate all the support and advertising that we have received from the Star Dust andall the members which joined us during the last 3 years and made the "Comet Crashers" one of the most successfullong term programs in not only our nature center, but also in our entire Natural & Historical Resources Division.

(Geoffrey Lane gives his thanks. The stargazing programs at Patuxent River Park will still continue. For moreinformation, call 301/627-6074 and askfor Jean Tierney.)

SOCKETS AND PEBBLES

small rock - Sol 71

This close-up Sojouner rover image of a small rock shows that weathering has etched-out pebbles toproduce sockets. In the image. sunlight is coming from the upper left. Sockets (with shadows on top) arevisible at the lower left and pebbles (with bright tops and shadowed bases) are seen at the lower center andlower right. Two pebbles (about 0.5 cm across) are visible at the lower center.

To view more images from the Mars Pathfinder October 8, 1997 Press Conference, you can find them at thefollowing web site: mpfwww.jpl.nasa.gov/ops.htlm - ed.

Julie McCall739 Rock Creek Church Road, NWWashington, DC 200 10

Norman C. Peterson17732 Caddy DriveDerwood, MD 20855

John & Abigail Ward(Juniors: Nat & Katie)5511 39th Street, NWWashington, DC 200 15

Vincent McCullough13899 Ferrara CourtChantilly, VA 20151

Zacharias P. Walters~ Jr.3605 Astoria RoadKensington, MD 20895-1404

National Capital Area Astronomical EventsFree Lectures at the Einstein Planetarium and Other Daily Events

National Air & Space Museum

202/357-1550,202/357-1686, or 202/357-1505 (TTY)Home page: http://www.nasm.edu

Other Planetariums,Observatories, and Science

Centers in the Area

Montgomery College Plan-etarium -"Total Solar Eclipses"Takoma Park, MD. November 15.(See their web site at http://myhouse.com/mc/planet.htm. )

Campus Observatory OpenHouse - "Life in the Universe",speaker: Dr. Virginia Trimble. De-partment of Astronomy, Universityof Maryland, College Park, MD.November 5, 8:00 PM.

"Nemesis - The Sun's Compan-ion", speaker: Dr. Roger Bell. De-partment of Astronomy, Universityof Maryland, College Park, MD.November 20, 8:00 PM.

U.S. Naval Observatory Collo-quia -"GPS Applications in theNASA Solid Earth and Natural Haz-ards Program", speaker: Dr. ClarkWilson of Nasa Headquarters andUniversity of Texas, Austin. U.S.Naval Observatory, Building 52,Room 300, Washington, DC. No-vember 14, 10:30AM. Information:202/762-1437.

Mount Rainier Nature & Recre-ation Center - "Moon Madness"November 14, 7:00-8:30 PM. His-toric Bladensburg Waterfront Visi-tors Center, 4601 Annapolis Rd,Bladensburg, MD. Due to construc-tion, activites at the Waterfront Cen-ter may be moved to an alternate site.Call Jean Tierney at 3011627-6074for information.

Center for Adult Education -"Observing the Highest Energy Par-ticles (>1()2°eV) from Space" No-vember 13-15. UniversityofMaryland, College Park, MD. Seesidebar for details.

Check your local web sites for anyother events that may be happeningin the area.

Newsletter Deadline forDecember Star DustNovember 15,1997

Send Submissions to Alisa & Gary Joaquin, at 4910 Schuyler Dr, Annandale, VA,22003-5144, Leave a message on voice mail703n50-1636. Text files or graphic filesin .GIF or .TIFF may be sent via E-Mail to ajglj@erols.comorfaxsubmissionst0703/658-2233. No submissions will be accepted after the 20th. There will be noexceptions. We need a reasonable amount of time to design, edit, and review thisnewsletter. We would appreciate everyone's help in this matter. Thank you.

Cosmos RevisitedNovember

November 4 Star Formationby Anneila Sargent

November 18 Extrasolar Planetsby Geoff Marcy

November 25 Special Viewing ofIMAXFilm,"Cosmic Voyage"

Lectures begin at 6:00 PM at the Na-tional Air and Space Musem. For moreinformation, call Missy Snelling at 202/357-4260.

Workshop on"Observing the Highest

Energy Particles(>1()2° eV) from Space"

November 13,14, and 15Center for Adult Education

University of Maryland

Consecutive topics will be presented inthe following areas:

Potential Observation from SpaceNew Physics and AstrophysicsDetector PhysicsProperties of the Atmosphere as aDetector Seen from SpacePlans for Ground Based Observations

Registration Fees:$231.00 ($31.00 lunches and breaks)Dinner (Nov. 13) cost is $29.00

You may register electronically or con-tact Jonathan Ormes by email:Ormes@ Iheamail.gsfc.nasa.gov.

Information about the University ofMaryland Conference Center is locatedat http://www.ri1arriot.com/confcenterslW ASUM/Index.htm.

If hotel accommodations are required, alimited number of sleeping rooms havebeen reserved at The Inn at the Univer-sity of Maryland Check our website forconference information and other hotellistings and their rates. (http://1hea www.gsfc.nasa.gov/docs/gamco sray /hecr/Conference s/U971113IUHECR)

SERVING SCIENCE & SOCIETY SINCE 1937NCA is a non-profit, membership supported, volunteer run, public-service corporation dedicated to advancing space technology,astronomy, and related sciences through information, participa-tion, and inspiration, via research, lectures, presentations, publica-tions, expeditions, tours, public interpretation, and education.NCA is the astronomy affiliate of the Washington Academy ofSciences. All are welcome to join NCA. For information:703/841-4765.

SERVICES & ACTIVITIES:Monthly Meetings feature presentations of current work by re-

searchers at the horizons of their fields. All are welcome; thereis no charge. See monthly Star Dust for time and location.

NCA Volunteers serve as skilled observers frequently deployingto many parts of the National Capital region, and beyond, oncampaigns and expeditions collecting vital scientific data forastronomy and related sciences. They also serve locally byassisting with scientific conferences, judging science fairs, andinterpreting astronomy and related subjects during public pro-grams.

Discussion Groups exchange information, ideas, and questions onpreselected topics, moderated by an NCA member or guestexpert.

Publications received by members include the monthly newsletterofNCA, Star Dust, and an optional discount subscription to Sky& Telescope magazine.

NCA Information Service answers a wide variety of inquiriesabout space technology, astronomy, and related subjects fromthe public, the media, and other organizations.

Consumer Clinics on selection, use, and care of binoculars andtelescopes, provide myth-breaking information, guidance, anddemonstrations for those contemplating acquiring their firstastronomical instrument.

Dark-Sky Protection Efforts educate society at large about theserious environmental threat of light pollution, plus seek waysand means of light pollution avoidance and abatement. NCAis an organizational member of the International Dark-SkyAssociation (IDA), and the National Capital region's IDArepresentati ve.

Classes teach about subjects ranging from basic astronomy tohand-making a fine astronomical telescope. NCA's instruc-tors also train educators in how to better teach astronomy andrelated subjects.

Tours travel to dark-sky sites, observatories, laboratories, muse-ums, and other points of interest around the National Capitalregion, the Nation, and the World.

Discounts are available to members on many publications, prod-ucts, and services, including Sky & Telescope magazine.

Public Sky Viewing Programs are offered jointly with theNational Park Service, the Smithsonian Institution, the U.S.Naval Observatory, and others.

NCA Juniors Program fosters children's and young adults'interest in space technology, astronomy, and related sciencesthrough discounted memberships, mentorship from dedicatedmembers, and NCA's annual Science Fair Awards.

Fine Quality Telescopes up to 36-cm (l4-inch) aperture areavailable free for member's use. NCA also has access toseveral relatively dark-sky sites in Maryland, Virginia, andWest Virginia.

Enclosed is my payment for the following membership category:.[ ] Regular

[ ] Sky & Telescope and Star Dust. ($54 per year)[ ] Star Dust only ($27 per year)

[ ] Junior (Only open to those under age 18) Date of birth: _Junior members pay a reduced rate.[ ] Sky & Telescope and Star Dust. ($42 per year)[ ] Star Dust only ($15 per year)

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If family membership, list names of additional participating immediate family members in same household, with birthdates of allthose under 18 years old: _

Note: If you already subscribe to Sky & Telescope, please attach a recent mailing label. You may renew this subscriptionthrough NCA for $22 when it expires.Make check payable to: National Capital Astronomers, Inc., and send with this form to:NCA c/o Jeffrey B. Norman, 5410 Connecticut Avenue, NW, Apt. #717, Washington, D.C. 20015-2837.The following information is optional. Please indicate briefly any special interests, skills, education, experience, or otherresources which you might contribute to NCA. Thank you, and welcome to NCA!

Getting to the NCA Monthly MeetingMetrorail Riders - From Medical Center Metro Station:Walk down the hill, pass the bus stops and turn right at theanchor onto Center Drive. Continue uphill to Building 10,the tallest building on campus (walking time about 10minutes). Also, the 12 bus line connects the Bethesda (7: 16PM) and NIH (7:23 PM) Metro stops with Building 10 (7 :25PM).

To Faryab Afghan Restaurant - Take Wisconsin Avenuetoward Bethesda and head right onto Woodmont Take aright onto Cordell. The restaurant is at 4917 Cordell. Thereare parking garages nearby.

SlIlr Dust is published ten times yearly (September throughJune) by the National Capital Astronomers, Inc. (NCA), anonprofit, astronomical organization serving the entireNational Capital region, and beyond. NCA is the as-tronomy affiliate of the Washington Academy of Sciencesand the National Capital region's representative of theInternational Dark-Sky Association. NCA's Phone Num-ber 03/841-4765. President: Harold Williams, 301/565-3709. Deadline for Star Dust is the 15th of the precedingmonth. Editors: Alisa & Gary Joaquin, 4910 SchuylerDr., Annandale, VA 22003, 703/750-1636,E-mail: ajglj@erols.com. Editoral Advisor: Wayne H.Warren, Jr. Star Dust © 1997 may be reproduced withcredit to National Capital Astronomers, Inc.

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Enter B uilding 10 from North (M ainEntrance); passing through thedouble doolS. Turn left and followsigns for Lippsett Audilooom. Ifunsure. ask for directions at theInformation Booth inside MainEntrance.

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