Category Archives: 1995

PeGASus Newsletter Issue #61 – Nov. 1995

The PGAS meets next on November 29 at 7:30 PM Room 2-223 at CNC


CONTENTS

Editorial
Coming Events
In The Sky
Astronomy at the Museum
AstroSurfing
Membership Application Form
(not necessarily in that order)


The PeGASus is published monthly by the Prince George Astronomical Society. Contributions to the newsletter are welcome.

Send correspondence to: The PGAS 3330 – 22nd Avenue Prince George, B.C. V2N 1P8 or Aaquist@cnc.bc.ca

The PGAS is a nonprofit organization dedicated to the advancement of science and astronomy in the Prince George region and neighbouring northern school districts.

OUR PURSUITS ARE ASTRONOMICAL OUR ACTIVITIES ARE OUT OF THIS WORLD OUR AIM IS THE SKYOur observatory is located near West Lake on Tedford Road, 10 kilometres from Highway 16 down Blackwater Road. For hours of operation, call someone on the Executive. The observatory phone number is 964-3600. This is a party line, so a busy signal does not imply that someone is there.


PRINCE GEORGE ASTRONOMICAL SOCIETY EXECUTIVE, 1994/5

President: Jon Bowen 563-9869 Vice President: Bob Nelson 562-2131/563-6928 Secretary: Brian Potts 562-8113 Treasurer: Barb Hansen 962-7477

Members at Large:

Gil Self 964-7279 Eric Hansen 962-7477

Nominated Positions:

Technical Director: Bob Nelson Observing Director: Jon Bowen Building Director: Mike Hansen Promotional Director: Jennifer Whitman Financial Director: David Sundberg PeGASus Editor: Orla Aaquist


EDITOR’s COMMENTS

At October’s annual general meeting, Barb Hansen ran against Dave Sundberg for the position of treasurer, and Brian Potts ran against Mathew Burke for the position of secretary. For the two positions of member-at-large, we had four members running: Gil Self, Eric Hansen, Dave Sundberg, and Orla Aaquist. Even though I gave a passionate speech on my own behalf detailing all of my shortcomings, Dave and I were defeated by Gil and Eric.

In my mind, the outcome of the voting is not so important. What is more important is that the club has enough members who are willing to take an active part in the club’s activities. You do not need to be a member of the executive, or be one of the appointed directors, in order to become involved. You just have to have a desire to do something. For me, producing this newsletter is very enjoyable. It takes about one entire day to fill in the blanks and it takes another half day getting it printed, photocopied, and mailed out to you. I do not need to be on the executive in order to do this. Although Jon is trying to get me on the executive by creating another director’s position, there is no need to do this since it will not change what I am doing on behalf of the PGAS.

Because our club is growing, there is a great need for members to get involved. One way of doing this is to attract new members, because the more members we have, the greater is the chance that someone will be inspired to do something like plaster the walls, paint the walls, widen the driveway, build an observing deck, find us some money, host a neighbourhood star party, build a telescope, find some flooring, find some concrete, finish the basement, make an observatory sign, recruit new members, finish the darkroom, take some astrophotographs and make some postcards, make membership cards, start a youth group, learn how to use the club telescopes, teach others how to use the club telescopes, visit schools to show slides, hold public viewing sessions at UNBC, CNC, Fort-George Park, Civic Centre, and schools, look up at the night sky, build a bookshelf, frame some posters, share your thoughts about astronomy with other members, start an armchair astronomy session, start a

new-members learning group, develop a new-members’ information package, put together a promotion package, collect old astronomy books, search the library for interesting projects in astronomy, show the stars to your friends, build another picnic table, call a fellow member, catch the mice at the observatory, come up with a list of ideas of what the club should be doing, bring some friends out to the observator, count some meteors,


COMING EVENTS

If you are involved with any astronomical or otherwise scientific activity on behalf of the PGAS, please list the activity here.

Nov 25: If you get this newsletter on time, watch for a nice occultation occurs on the evening of November 25th, when the young crescent Moon overtakes 3rd-magnitude Rho-1 Sagittarii. See the map on page 80 of the January (?) issue of Sky and Telescope, but note the time tick should read 24:00 UT, not 23:50. You can call 301-474-4945 for updates or check out the WWW site http://www.sky.net/~robinson.

Nov 29: monthly meeting at the College of New Caledonia. The constellation of the month presentation is on Perseus. Afterwards, a video will be shown about the Shoemaker-Levy comet collision with Jupiter. Also discussed in this video is the risk we face from a similar collision with the earth. If it is clear, have a look at the first quarter moon through the college’s C8.

Dec 16: Christmas Party at someone’s house.

Dec 27: NO MEETING. No PeGASus.

Dec 13: Executive meets at the Xerox office. All members are welcome to attend and directors are requested to attend.

Dec 31: Mathew and Susan are getting married.

Jan 31: Monthly meeting at the College of New Caledonia. The constellation of the month presentation is on Orion. Afterwards, Bob Nelson will talk about variable stars.

Feb 28: Orla speaks on planetary nebulae.


A N N O U N C E M E N T S

If you have anything to announce or advertise, consider this space of the PeGASus. Welcome to the Club Catherine Verpaelst and Todd Whitcombe.

Thank You to all those who volunteered to help out at the Pine Centre booth during Science and Technology weekend. Participants were Don Goldie, Barb Hansen, Eric Hansen, Jon Bowen, Mike Hansen, Sean Ollech, Vince Hogan, Gerhard Bierman, Ted Biech, Gil Self, Steven Senger, Lance Odiorn, Mathew Burke and Shannon Austman. I sure hope I didn’t miss anyone. I think we had a really successful exhibit this year.

Belated Thanks to our one and only youth member, Sean Ollech, for spending some time at our P.G. Exhibition booth this summer. I think Sean was one of the few people who came out to help man the booth.

New Executive Al last month’s elections, a few changes to the executive was made. Barb Hansen was voted in as treasurer (replacing Dave Sundberg), and Brian Potts was voted in a secretary (replacing Mathew Burke). At an executive meeting following the annual general meeting, Mike Hansen took over the appointed position of Observatory Director from Eric Hansen, and Dave Sundberg was appointed for the new position of Financial Director.

Public Viewing Public viewing at the observatory will stop for the season at the end of November. They will begin again in the spring.

Membership Dues are Due Your annual dues of $20 are necessary in order to maintain this wonderful newsletter, pay the observatory’s utilities, and buy cookies.

Last Call for Calendars

At the start of November, Orla ordered 50 1996 Astronomy Calendars form the RASC in Vancouver. They are all sold. He will order more calendars, if there is a demand. Give him a call at 964-9626 before the end of November if you are interested. They are really nice calendars, and will make a great Christmas present. They are only $7.50 for members.

Darkroom is Developing The Fraser-Fort George Regional Museum has donated more darkroom equipment and chemicals. It looks like we have enough ‘stuff’ to build a working darkroom at the observatory. Gill Self estimates that we have acquired over $500 of materials from the museum. All we need now are sinks and a water supply. THANKS FFGRM.

Who wants to host this year’s Christmas Party on December 16?


ASTROSURFING

Details of the Science News posted here are available on the astronomy forum on the Prince George Free-Net.

NASA has begun flight testing an experimental aircraft wing panel that has Supersonic Laminar Flow Control (SLFC).

NASA physicists using the Ulysses spacecraft have obtained the first “snapshot,” of the spiral structure of our solar system’s magnetic field. These lines of magnetic force originate in the Sun and extend outward into the solar system. The aerial photo of the interplanetary magnetic field became possible with the flight of Ulysses over the south pole of the Sun in 1994. Now we could look down on the solar system.

Astronomers are now fairly certain that a planet is orbiting 51 Pegasi, a Sun-like, main-sequence star of spectral type G5 situated 42 light-years from Earth. Several observers have confirmed an announcement made by Michel Mayor and Didier Queloz of Geneva Observatory. The planet is lies only 7 million kilometers away from it – equal to just 1/20 of Earth’s distance from the Sun. Orbiting so close to the star, this world would be heated to 1,000 deg Celsius, and it’s likely a nearly molten ball of iron and rock. To create the observed wobble in 51 Peg’s spectrum, the planet needs a mass at least half that of Jupiter. 51 Pegasi is magnitude 5.5 and easily visible in binoculars; however, don’t expect to see the planet.

NASA’s Galileo spacecraft is proceeding toward its December rendezvous with Jupiter, with spacecraft engineers greatly relieved at last weekend’s test results showing that its onboard tape recorder remains functional. The suspicion is that part of the tape has weakened, causing it to slip in the transport mechanism.

Planetary astronomers recently got their first look at a crude compositional map of the asteroid 4 Vesta, thanks to images taken at several key wavelengths by the Hubble Space Telescope. Vesta, the third largest asteroid, is known to exhibit bright and dark markings. The new Hubble data suggests that one hemisphere is dominated a type of basalt similar to many lava flows on the Earth’s surface. The other half has the spectral signature of a basalt that solidified underground.

A team led by NASA researchers has devised a miniaturized sensor system that could be a catalyst for a revolutionary new generation of small, low-cost spacecraft to explore the solar system. The Planetary Inte-grated Camera-Spectrometer, or PICS, is ex-pected eventually to replace whole suites of individual spacecraft instruments. Its develop-ment represents a crucial step toward enabling future NASA missions that will have to use smaller launch vehicles and, hence, smaller spacecraft to travel to distant planets and other bodies in the solar system.

What some scientists are calling ‘the most dramatic images yet taken by the Hubble Space Telescope was presented at 3 p.m. EST, Thursday, Nov. 2, 1995, in the NASA Headquarters Auditorium, 300 E St. SW, Washington, DC. The images reveal dark pillar-like structures in the Eagle Nebula (also called M16). These structures are thought to be incubators for new stars and are called “EGGs” (Evaporating Gaseous Globules”).

An extremely lightweight camera and a variety of instruments designed to study daily weather patterns and the icy south pole on Mars have been selected by NASA officials to fly aboard an orbiting spacecraft and lander in late 1998, known as the Mars Surveyor ’98 Orbiter and the Mars Surveyor ’98 Lander.

The latest information about NASA’s Galileo Probe mission and other information about the solar system’s largest planet, Jupiter, is now available on the Internet. Information can be accessed on the World Wide Web at URL: http://ccf.arc.nasa.gov/galileo_probe/

Measurements of interstellar Helium have improved over the years to such an extent that various theories can soon be put to the test. Not only are cosmological theories at stake but various features of the standard model of particle physics.

Hubble will soon be joined in space by the Infrared Space Observatory built by the European Space Agency.

A huge interplanetary disturbance struck the Earth’s protective magnetic field on Oct. 18, producing a magnetic storm and auroral displays, or “Northern Lights” that persisted for two days. The phenomenon was visible in the United States as far south as Denver.

The Sun has passed through a series of Saturn-ring-plane crossings which began in May and August and will conclude in February. The crossing times have been coming late by at least 20 minutes. This means either the planet’s spin axis is precessing at only about 2/3 the predicted rate or, more likely, our knowledge of the pole’s location is off by about 2 arcseconds.


IN THE SKY ALGOL, THE “DEMON STAR” by Alan Whitman

The constellation Perseus represents a mythical hero. He carries the head of the monster Medusa, a gorgon with snakes for hair whose gaze turned men to stone (the origin of the phrase “a petrifying glance”). Perseus managed to avoid the monster’s eyes by looking at its reflection in his polished shield while slaying it. Medusa’s head is represented by Algol, the first star that 17th century astronomers noticed varying in brightness.

However, the classical identification of a bright variable star with the head of a demon strongly suggests that the variability was known in ancient times.

Algol consists of two stars orbiting their mutual centre of gravity, with the plane of their orbits nearly aligned with our line of sight to the system. Once every 2.9 days the brighter star of the pair is partially eclipsed when the larger but fainter companion star passes between the bright star and us. Dr. Bob Nelson studies similar eclipsing binary systems at the PGAO.

When viewing the sky with the unaided eye, most stars appear the same brightness night after night but not Algol, the demon star! Most nights Algol is as bright as Gamma Andromeda, to Algol’s right (west) on the star chart (see page opposite). Normally, Algol is about four times as bright as Rho Persei, the star just below (south of) Algol. When Algol is being eclipsed, it fades slowly for four hours. Then for two hours at mid-eclipse it is as faint as nearby Rho, before brightening again. You will find that Algol’s changing brightness is easily judged by comparing it with adjacent Rho.

Algol will be partially eclipsed and consequently be at minimum brightness for two hours centered on the times in the box at the end of this article.

Algol is not the only Perseus gem visible with your unaided eye in a dark sky. “The Double Cluster” is easily found as a hazy spot midway between the prominent arc of stars through Alpha Persei and the “W” of the constellation Cassiopea. Binoculars will start to resolve “the Double Cluster” into faint stars while the view in a small telescope will delight you. The 24″ shows several prominently orange stars.

Below Perseus is the bright Pleiades star cluster, also known as “The Seven Sisters”. Most people see six or seven tightly clustered stars but keen-eyed persons may glimpse eleven or more without optical aid. Binoculars will show the Pleiades’ full glory, revealing several chains of fainter stars.

Binoculars will easily show the cluster M34 about 40 percent of the way from Algol to Gamma Andromedae. After finding it, you should be able to see it with your unaided eye if you observe from dark country skies.

Finally, use your binoculars to sweep between the Perseus stars Alpha and Delta. You will discover a marvellous swarm of young luminous stars called the Alpha Persei Association.

By month-end you should see Venus becoming more prominent in early evening twilight. It will be a brilliant “Christmas Star”, joined by a crescent moon on December 23rd and Christmas Eve.

Minima of Algol Look for a decreasing light output of Algol two hours before or after the times given here. Sunday Nov 26 5:55 PM Friday Dec 8 5:11 AM * Monday Dec 11 2:01 AM Wednesday Dec 13 10:50 PM Saturday Dec 16 7:39 PM *between November 26th and December 8th the eclipses occur during daylight from this longitude.


ASTRONOMY AT THE MUSEUM by Orla Aaquist

In conjunction with the Fraser-Fort George Regional Museum, I am in the process of developing new physical science programs which address the Elementary Schools’ new curriculum. Among these are two astronomy programs, one for grade 6 and the other for grade 7.

The theme of the grade 6 program is Exploration of the Solar System. This program begins with a slide presentation which takes the students for a trip through the solar system. The slides are mostly images taken in the last two decades by unmanned satellites like the Voyager, Viking and Magellan satellites.

After the slide presentation, the students group into four teams. Each team is given a different picture of some solar system object, and they have to decide (as a group) what the object is. If they guess correctly, the team keeps the card; if they guess incorrectly, the card is given to another group during the next round. At the end of 10 minutes, the group with the most cards is declared the winner. This usually turns out to be quite a lively, competitive game. The images were cut from old Astronomy magazines, mounted on file cards and laminated.

When students visit the the museum, they like to explore the Exploration Gallery and the History Hall. We focus their exploration on astronomy by asking them to find objects which have one or more characteristics of some solar system object. Each team is given a sheet containing a list of solar system objects, and next to each object is a brief description of some of the objects’ main features followed by a blank. They are given 10 to 15 minutes to search the museum and fill in the blank with some museum artifact.

Afterwards, one spokesperson from each group reads out their list. For example, a cross cut of a tree’s trunk can represent Saturn because both have rings, and the tail of a fox can be likened to a comet because they both have fuzzy tails.

If time permits, the students also build a model solar system. Several spheres, of about the right proportion, represents the planets. Each team first decide what sphere should represent what planet. Then they lay the planets out on the floor using the Earth’s orbit as a scale. A long measuring tape with the correct scale marked on it is used to judge which team made the best placement.

PeGASus Newsletter Issue #56 – April. 1995

CONTENTS


Editorial
Monthly Meetings
In The Sky
Faces of Saturn
May Moons
The Binocular Advantage
May Calendar
AstroSurfing
(not necessarily in that order)


The PeGASus is published monthly by the Prince George Astronomical Society. Contributions to the newsletter are welcome.

Send correspondence to:
The PGAS
3330 – 22nd Avenue
Prince George, B.C.
V2N 1P8
or
Aaquist@cnc.bc.ca

The PGAS is a nonprofit organization dedicated to the advancement of science and astronomy in the Prince George region and neighbouring northern school districts.

OUR PURSUITS ARE ASTRONOMICAL

OUR ACTIVITIES ARE OUT OF THIS WORLD

OUR AIM IS THE SKY

Our observatory is located near West Lake on Tedford Road, 10 kilometres from Highway 16 down Blackwater Road. For hours of operation, call someone on the Executive. The observatory phone number is 964-3600. This is a party line, so a busy signal does not imply that someone is there.


PRINCE GEORGE ASTRONOMICAL SOCIETY EXECUTIVE, 1994/5

President: Jon Bowen 563-9869
Vice President: Bob Nelson 562-2131/563-6928
Secretary: Matthew Burke 563-2162
Treasurer: David Sundberg 562-5774/6655

Members at Large:
Gil Self 964-7279
Eric Hansen 962-7477

Nominated Positions:
Technical Director: Bob Nelson
Observing Director: Jon Bowen
Promotional Director: Orla Aaquist
PeGASus Editor: Orla Aaquist
Librarian: Donovan Unruh


EDITORIAL COMMENTS:


This month I have been fooling around with some software which has once again found their way onto my hard drive after many months of hibernation on floppies due to lack of disk space. My disk space has now doubled, so they are back on line. I have tried to import some graphics and text from a couple of sources, and I wouldn’t mind some feed back as to how you like the inclusion of graphics. They will get better with practice.

Cutbacks at the College of New Caledonia has made my faculty position at the college very uncertain. In fact, I was given official layoff notice at the end of March. There is a remote possibility that the layoff will be rescinded or that I will secure other employment in Prince George; however, I have been actively seeking employment elsewhere, so I am looking for someone who wants to take over this newsletter. It will be hard for me to give it up because I really do enjoy the challenge of filling up these pages and nagging at you to send me more copy. If you have any desire to publish (or help publish) this newsletter, please give me a call. It is not necessary for you to own a computer and software, since use can be made of the PGAO computer or arrangements can be made with Bob Nelson to use the physics computers. All you need are some typing and computer skills.

I would like to make an appeal to members using the observatory. Please keep in mind that others use it too. If you leave a mess behind or forget to return something to its proper place, then it makes it inconvenient for the next user. If something breaks or you discover a problem, please record it on the login sheets by the front door AND call Bob Nelson and Jon Bowen to let them know of the problem. In turn, members should give Jon or Bob a call before going to the observatory in order to check if there have been any major problems reported. It is frustrating to come all the way to the PGAO just to find that the drive doesn’t work or someone has borrowed the eyepieces. Here are a couple of specific complaints: books and papers were left all over the table next to the comuter; moldy coffee was found in our coffee pot (I took it home to clean); the unplugged refrigerator door was left closed and mold has begun to grow in the refrigerator (someone has to clean it); dirt is accumulating on the observatory floor (someone must damp mop it once in a while — sweeping will raise too much dust). REMEMBER, WE DO NOT HAVE JANITORIAL SERVICE AT THE PGAO; THAT’S YOUR JOB.

Articles on any topic with some astronomical connection are accepted. For example, you could have been walking in Fort-George park after midnight when suddenly you were mugged and your wallet stolen. The thief struck you on your head and you saw stars. The word stars makes the astronomical connection, so your article would be accepted for publication in this newsletter.

Another example could be as follows. You got up one morning and as usual took the box of cereal out of the cupboard and the milk out of the refrigerator. Your black cat ran across your path as you were walking towards the kitchen table and (of course) you tripped over your own feet and spilled the milk on your way to the kitchen table. In this story, the words milk and way make the astronomical connection.

So, with these standards of acceptance, you too can become published. If you are looking for a job, like some people in this club are, you can include your contribution on your resume.

The Curse of Northern Astronomy: The Sun is getting higher and higher in the sky and rising earlier and setting later. It is the curse of astronomy in the north. At the first of May, the Sun is moving rapidly to its summer solstice position (X) from its spring equinox position (X) again, and by month’s end it is effectively at its highest point in the sky, as shown in the diagram to the left (not included in text version) Astronomers start burning the midnight oil.


MONTHLY MEETINGS (by Orla Aaquist)

The next meeting of the PGAS will be held at CNC, roon 2-223 (physics laboratory) on Wednesday, April 26th at 7:30 PM.

Thanks to Dr. Elie Korkmaz from UNBC’s Physics Department for giving a wonderfully interesting talk entitled The very small and the very large: a very intimate connection at the March meeting.

This month’s meeting will feature Art Beaumont (a PGAS member) who will speak on

Kepler’s Fourth Law

which is a discussion of a statistical analysis of the variations between planet densities and their orbital inclination. Bob Nelson will also present his popular Constellation of the Month and Mat has some new Hubble images. Come out for some astronomy talk and a cup of coffee, tea or hot chocolate. See you there.

A N N O U N C E M E N T S

If you have anything to announce or advertise, consider this space of the PeGASus.

New Members Please welcome the following new members: Steve Senger and Dr. Elie Korkmaz from Prince George and Jan Meijer from Fraser Lake.

Mt. Kobau Star Party Anyone interested in signing up for this year’s Mt. Kobau Star Party should contact

Peter Kuzel
4100-25th Avenue,
Vernon, BC, V1T 1P4

or phone him at 604-545-1226. Peter is the Vice President of the Mt. Kobau Society.

Astronomy Day

This year’s astronomy day falls on Saturday May 6 in Prince George. All activities will be held at the observatory this year starting at 3 PM and finishing at midnight. Members and their family and friends are encouraged to attend. During the afternoon until sunset, solar viewing, slides, and demonstrations are on the menu.

The Astronomy Forum

on the Prince George Free-Net carries the latest astronomy news and happenings. Set your modem to 8 bit (1 stop bit), no parity, Xon/Xoff flow control and dial 563-3977. Logon as guest. At the ==> prompt, type go astro.

Thanks Jon!

Thank you Jon Bowen for representing the PGAS at the Central Interior Science Exhibition on Wednesday, March 29 at the Civic Centre.

Work Party

Its warmer and Bob Nelson (563-6928) wants to organize work parties at the observatory. These are much more fun than star parties, so come and join in the activities.

Furnace

We have enough money to buy a furnace, thanks to the $1000 donation by the Regional District. If anyone has furnace expertise, please contact Bob Nelson (563-6928) real soon.

PGAS Editor Wanted

Our current PeGASus editor may be leaving town (see editorial). If anyone out there has the desire to generate the PeGASus, please call Orla Aaquist at 964-9626.

Wanted

Sarah or Jacob, ages 13 and 11, are long on enthusiasm but short on funds and desire to purchase a telescope which is suitable for deep-space observations. Call them at 604-477-1502 (Victoria).


ASTROSURFING

Astronomy news gathered from surfing through the Internet and other sources. Much of the contents presented here are severely edited for presentation in this Newsletter. For more details, contact the PeGASus editor.

ASTRO 2 COMPLETES MISSION: The Astro 2 ultraviolet astronomy experiment aboard the Space Shuttle Endeavour in its latest flight will allow Johns Hopkins University professor Arthur Davidsen to observe a high redshift quasar long enough so that the mission’s most elusive goal detecting intergalactic helium may well be reached, thus solving one of cosmology’s outstanding mysteries.

UNUSUAL MARTIAN METEORITE: A meteorite, designated ALH84001, believed to have been blasted from the surface of Mars was collected in the Allan Hills region of Antarctica a decade ago, but its other worldly nature only became apparent last year. Unlike all other Martian meteorites, it is an estimated 4.5 billion years old nearly as ancient as Mars itself. Also, the rock contains carbonate minerals that were apparently deposited by a fluid on or under the Martian surface sometime in the distant past. Finally, the carbonates in ALH84001 are accompanied by traces of organic molecules called polycyclic aromatic hydrocarbons, or PAHs, which are based on interconnected benzene rings. The NASA team that discovered the organic compounds does not claim that they are related to some kind of Martian life form, but for now they have no clue to their origin. This find brings the total count of such rare objects to 11.

SHINY VENUS MOUNTAINS: A new theory could explain why the highest mountains on Venus are such very efficient reflectors of radar pulses from the Magellan spacecraft and ground based antennas. Apparently, the planet’s highest summits are capped with a “frost” of one or more metallic compounds. These minerals are known to be released as gases in volcanic eruptions on Earth and, by inference, those on Venus. Calculations show that a layer only a fraction of an inch thick, gradually accumulated over perhaps 10 million years, would possess the reflective properties that have stumped radar scientists since the 1970s.

HST’s VENUS and MARS: On March 21st NASA released new images of Venus and Mars taken by the Hubble Space Telescope. Venus was recorded in ultraviolet light by HST’s wide field camera and its high resolution spectrograph where sulfur dioxide (SO2) has a strong absorption. It appears that the amount of SO2 in the upper atmosphere is only about 20 times less than what was observed by the Pioneer Venus orbiter when it arrived there in 1978. These data suggest that the SO2 content of the planet’s atmosphere is not stable, probably affected by volcanic eruptions.

The new images of Mars reveal that the planet’s atmosphere is uncharacteristically free of dust right now. Back in the 1970s, during the Viking mission, the dust was about three times more opaque, and the sunlight it absorbed made the Martian atmosphere about 20 degrees C warmer than right now. The most recent images show ample evidence of frosts and clouds especially near the planet’s towering volcanos that have been scarce in years past. These images resolve the planet down to about 25 km and reveal a number of craters and other fine details. This new “weather report” from Mars will prove valuable to NASA engineers, who plan to use the Martian atmosphere as a speed brake for future spacecraft.

A DIMMER BETELGEUSE: Two astronomers at Villanova University report that Alpha Orionis, the gleaming red supergiant more widely known as Betelgeuse, has dimmed in brightness by 0.4 magnitude since September and now stands at +0.8. The star has been recognized as a semiregular variable since the time of John Herchel, and on occasion it can swing through a full magnitude. The variations last hundreds of days and are thought to be due to the gradual expansion and contraction of the star’s surface.

NEW SPACE RECORDS: Congratulations are in order for cosmonaut Valery Polyakov, who returned to Earth on March 22nd after spending a record breaking 439 days aboard the Mir space station. The previous mark was 366 days, set in 1988. Returning with Polyakov was Yelena Kondakova, who set a new space endurance record for women at 170 days.

EARTH’S INNER CORE MAY BE A SINGLE IRON CRYSTAL. Furthermore, the inner core’s magnetism might even influence the magnetic field shape we observe at the surface. Lars Stixrude of the University of Gottingen in Germany and Ronald Cohen of the Carnegie Institution of Washington have proposed a model in which the 2400km inner core consists of an immense collection of hexagonal close packed grains in a nearly perfect alignment. The properties of such an substance could help to explain the puzzling observation that seismic waves take longer to propagate through the planet in the plane of the equator than they do along the spin axis. Some scientists have reservations about this model. For example, how would the inner core’s magnetism work its way outward past the turbulent motion of the fluid outer core? (Science, 31 March 1995.)

OBJECTS AND FEATURES IN THE HEAVENS must be named according to a systematic protocol laid down by the International Astronomical Union (IAU). For example, features on Venus must bear female names: craters may be named after mortal women, but ridges must be named for sky goddesses. Uplands are named after goddesses of love and plains after mythological heroines. On Mercury valleys are named after radio telescopes while scarps take the names of famous ships of discovery. Features on Uranus’ moon Puck are named after mischievous spirits, while features on Neptune’s moons are all watery spirits. Little did Virgil know that persons and places in his epic poem Aeneid would 2000 years later be affixed to maps of Saturn’s moon Dione. And so on. (Sky & Telescope, May.)

THE ADVANCED PHOTON SOURCE (APS) is nearing completion at Argonne. The $811 million synchrotron light source uses 7 GeV positrons to produce short pulses of hard x rays. One of the chief functions of the APS will be as an x ray camera, taking still photos of proteins and movies of molecules on the move. APS’s chief rivals are the 6 GeV European Synchrotron Radiation Facility (ESRF) in Grenoble, France (finished last year) and an 8 GeV machine in Japan, to be finished in 1998. (Science, 31 March.)


IN THE SKY (by Alan Whitman)

Mercury puts on its most favourable evening apparition of the year in late April and early May. It is brighter in late April but farthest from the sun on May 11th. The best visibility should be right around Astronomy Day, Saturday May 6th. Look for it just above the WNW horizon in evening twilight. On April 30th Mercury will lie 4 degrees north of the very slender lunar crescent only 35 hours old. Mercury may actually be easier to see than the moon. While Mercury briefly becomes “The Evening Star” Venus remains “The Morning Star”.

Fading Mars is now accelerating its eastward motion back towards Regulus, which it passes 1 degree north of on May 23rd. Its motion should be quite apparent from week to week. Jupiter now rises in late evening, but at declination -22 degrees it is too far south for a very satisfactory telescopic view. Saturn enters the morning sky in May. The rings will be edge-on May 22nd as the earth passes to the south side of the ring-plane and Saturn will appear ringless for a day or two. From May 22nd through August 10th we view the dark side of the rings and you have a challenge to your planetary observing skills — more about this in the next month’s column.

Messier corner: I always read the observatory’s log to see what has happened since my last visit. One recent night Gil Self observed a great number of Messier objects but noted that M104 was the best. Try edge-on M104, “The Sombrero Galaxy”, yourself and see if you don’t agree with Gil. Here is my description from a night with the 24″ this spring: “spectacular M104 with its bright nucleus and the dark lane spanning the whole length of the galaxy at 225X”. If M104 hooks you on edge-on spiral galaxies, try another famous classic: “incredible 120X and 225X views of extreme edge-on NGC 4565 (15.2′ by 2.8′) with the dust lane easy near the nucleus. Central bulge and extremely thin disk. The galaxy spanned the whole 225x field!” Finally, here is a tougher one: “Leo edge-on NGC 3628 near M65 and M66 — the dust lane was barely visible at 120X and 225X.


FACES OF SATURN (by Orla Aaquist)

In a telescope, Saturn is the most spectacular of all the planets because of its rings. The two main rings are separated by Cassini’s division, which can be seen even in small instruments. The Rings are tilted 27 degrees to the plane of the ecliptic and slowly change their apparent tilt. On the morning of May 22 this year, the earth will pass through the ring plane of Saturn so that the rings are seen edge on. This happens twice every orbital period of Saturn (29.5 years); hence, approximately every 15 years the rings nearly disappear from view. The figure below shows how the view of the rings change with time. The first image is the view as seen one year ago (May 22, 1994), the second image shows the rings as they are now, and the third image shows the rings as they will look like next year in May. The last image gives the appearance in May of the year 2003 when the rings will be at their maximum tilt of 27 degrees with respect to our line of sight.

Jupiter is famous for its atmospheric bands and the four bright Galilean satellites which continually dance around its equatorial plane. Saturn, too, has satellites which dance around its equatorial plane; however, they are not as bright as the Galilean satellites of Jupiter. As many as eight satellites can be seen with the 24″ PGAO telescopes, four of which are easily visible in our C8. The satellites of Saturn are

Satellite mag Period(days)
Mimas 13.3 0.94
Enceladus 12.6 1.37
Tethys 10.6 1.89
Dione 10.8 2.74
Rhea 10.1 4.52
Titan 8.7 15.95
Hyperion 14.6 21.28
Iapetus 11.6 79.33

(The information and image used in this article was gleaned from PC-Sky software available on the PGAO computer)


THE BINOCULAR ADVANTAGE (by Robert Frith)

Most of us cannot afford a telescope. The cost of eyepieces, filters and other telescope accessories can easily steer one to a less expensive hobby. However, most households already have the fastest optics in astronomy … binoculars.

Fast as in setup, covering expansive sky, and finding objects by star hopping. Also, using the alt-azimuth, spinal-cranial drive system is much easier than using a telescope. While telescope users are polar aligning, the binocular astronomer is already well into an observing session. Image quality rivals well made refractors but at a fraction of the cost. Some astronomical objects are preferable in binoculars (i.e. NGC 7000, M33) since low light contrast in telescopes can be difficult, especially when using higher magnifications. Galaxies, asteroids, nebulae, double stars, star clusters, eight of our nine planets including four satellites of Jupiter are all within reach of the binocular observer. Scanning the terminator of the moon reveals individual craters and some of the higher mountains. With a dark sky, the naked eye can detect around 3,000 stars. With a pair of 7×50 binoculars you can see around 150,000 stars. Many astronomical objects from the Messier and NGC list can be found with ordinary binoculars.

The advantages are not only astronomical. I use my binoculars for scouting back country ski runs and route finding in mountain terrain. In this respect they are a safety feature as well as a pleasure item. I’ve sat in the backyard and spotted a variety of bird species. Binoculars offer undisturbed wildlife viewing. Sporting events, concerts are enhanced by this affordable item.

Expect to pay between $75 and $500 (even more) for a pair of multiple use binoculars. 7×50 and 10×50 are the choice for multiple use binoculars as they offer good magnification and are at the limit of hand held binoculars. Larger binoculars offer more light gathering ability, but they require a tripod for a steady image. 10×50’s give you a 5 to 6.5 degree field of view which is perfect for loose open clusters such as the Hyades and M44. Photography shops usually carry better quality binoculars than the ones found in department stores. Before purchasing a pair, I suggest reading Chapter 2 in The Backyard Astronomer’s Guide by Dickinson and Dyer. This book is available at the Public Library (main branch).

If someone offered me to trade my binoculars for their telescope, I would do so without hesitation, but the very next day I would go out and buy another pair.


END OF NEWSLETTER