In The Sky
Faces of Saturn
The Binocular Advantage
(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:
3330 – 22nd Avenue
Prince George, B.C.
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
Technical Director: Bob Nelson
Observing Director: Jon Bowen
Promotional Director: Orla Aaquist
PeGASus Editor: Orla Aaquist
Librarian: Donovan Unruh
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 There is a remote possibility that the layoff will be rescinded or that I will secure other employment in Prince George; however, I have been actively seeking employment elsewhere, so I am looking for someone who wants to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
Vernon, BC, V1T 1P4
or phone him at 604-545-1226. Peter is the Vice President of the Mt. Kobau Society.
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.
Thank you Jon Bowen for representing the PGAS at the Central Interior Science Exhibition on Wednesday, March 29 at the Civic Centre.
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.
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.
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).
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.