PRESIDENT/EDITORíS REPORT

Well, this is my last report as both President and Editor. In February, Iíll just be a "reporter of news" rather than a "maker of news."

If you read nothing else in this issue, you owe it to yourself to read Dave Turnerís October meeting reportóits a riot!

Since the last issue, there has been considerable "physical" progress at the St. Croix observatory site. The observing area has been cleared of trees and a base of gravel for the driveway/parking area has been spread (by hand!). Now that the ground is frozen, the only work that will be done before spring is the clearing of brush and some surveying.

The site is ready to use for observing, so why not give it a try?


1994/95 ANNUAL MEETING MINUTES: NOVEMBER 17, 1995

COMPILED BY: TOM HARP, SECRETARY

The meeting was called to order at 20h13 at the Nova Scotia Museum of Natural History, Halifax.

APPROVAL OF THE MINUTES OF LAST YEARíS ANNUAL MEETING

Approval of last yearís minutes as published in the December issue of Nova Notes was moved by Mary Lou Whitehorne / Blair MacDonald. Motion Carried.

REPORTS FROM MEMBERS OF THE EXECUTIVE

a) President (David Lane) - The Presidentís report will be published in the December issue of Nova Notes.

b) Second Vice-President (Shawn Mitchell) - The Second Vice-Presidentís report will be published in the December issue of Nova Notes.

c) Treasurer (Ian Anderson) - The Centreís financial report for the fiscal year ending September 30, 1995 was presented (Editorís Note: His report is published elsewhere in this issue). A letter was received from and read by the Centreís Auditor, Larry Bogan stating that he had reviewed the financial report for FY-95 and that the report reflects the true financial position of the Halifax Centre of the Royal Astronomical Society of Canada. A motion to approve the report was made by Nat Cohen/Blair MacDonald. Motion carried.

MOTION TO AMEND THE CENTREíS CONSTITUTION

As published in Volume 26, Issue 5 (October 1995) of Nova Notes, the following motion was presented to the membership:

It is moved that Clause 8.06 (2) be replaced with the following:

"No person may hold the office of Secretary, Treasurer, or National Council Representative for more than five consecutive terms, but such person may be re-elected after a lapse of one year."

The motion was made by Blair MacDonald/Paul Gray. Motion Carried by a greater than 2/3 majority.

ELECTION OF OFFICERS

At the October meeting of the Centre, a general call for nominations for the Centre Executive Council was made. There being no reply to this call, the candidates recommended by the Nominating Committee were declared elected as follows:

President - David Chapman
First Vice-President - Blair MacDonald
Second Vice-President - Shawn Mitchell
Secretary - Tom Harp
Treasurer - Ian Anderson
Observing Chairman - Paul Gray
Nova Notes Editor - David Lane
National Council Representative - Pat Kelly
Librarian - Clint Shannon
Councillors - David Turner, ML Whitehorne, Darren Talbot
Cookie Chairman - Ralph Fraser

ELECTION OF AUDITOR

A motion was made to elect Larry Bogan as the Centreís Auditor for 1996. The motion was made by Blair MacDonald/Tom Harp. Motion carried.

OTHER BUSINESS

There was no other business.

The meeting was adjourned at 20h35 on a motion by Blair MacDonald.

(Editorís Note: The year-end presidentís and 2nd VPís report will appear in the next issue.)


THE ASTRONOMY OF NATIVE AMERICANS:

BY DIANE BROOKS, HALIFAX CENTRE

Historic Native North Americans used earthly structures, both natural and artificial, and objects in the sky to determine their calendar and the time for their ceremonies. Rituals were very important events in their lives and had to be timed precisely, not only for their physical prosperity, but also for their spiritual well-being. Some of the ways various tribes used astronomical observations will be described.

The so-called medicine wheels, stone patterns on the ground, may be the most familiar structures, believed to have been built by the Plains Indians in the West. The wheel in the Bighorn Mountains, northern Wyoming, consists of cairns, spokes and a rim. The number of spokes is close to the number of days in a lunar month. Two cairns can be used with the central cairn to sight the sunrise and sunset at the summer solstice. Other cairns can be used to sight Aldebaren, Rigel and Sirius in the following way. The heliacal rising of Aldebaren marked the summer solstice at the time the wheel was believed to have been built, 200 to 400 years ago. Then, Aldebaren would have been visible only a few minutes before the predawn glow from the Sun washed it out. Twenty-eight days later, Rigel would rise in the same way over a second line of cairns. Sirius would repeat this pattern over a third line of cairns 28 days after that. The odds against chance alignments to the measured accuracy have been calculated at greater than 4000 to 1. These solar alignments would have been useful for millennia. The wheel resembles the plan of the Cheyenne medicine lodge which was built to celebrate the Sundance ceremony, the most important Plains Indian ritual held in the summer, and practiced at the summer solstice by some. The wheel may have been used to mark the calendar, especially the summer solstice, so that the Sundance ceremony could be timed to correspond with the solstice.

There are other medicine wheel sites east of the Rockies, across the Great Plains, and primarily north of the Bighorn Wheel. They appear to have been constructed above about 45į latitude. Ten have been found in Saskatchewan and at least 30 in Alberta. One of the most noteworthy Canadian wheels is at Moose Mountain, Saskatchewan, an area that was associated with the sky in Native legend. With five spokes and no rim, its structure is simpler than the Bighorn Wheel, and may be an earlier version. It is twice as large in diameter. The significant point is that it contains the same number of cairns and in the same relative positions as the Wyoming wheel. The cairns show the same alignments with Aldebaren, Rigel and Sirius, but for 2000 years ago, due to precession. Its age has been verified by radio-carbon dating of charcoal at the bottom of the central cairn where the ground was burned before construction. The evidence is that the fire occurred about 2600 years ago. Incidentally, one of the cairns would have aligned with Capella when it was far enough south to rise and set. For several hundred years this star would have been an ideal marker for north. At the end of the summer solstice sunrise spoke there is a small Sun symbol made of stones.

This Sun symbol has been found at two other candidates for astronomical wheels in Saskatchewan. More than half of the wheels examined in Alberta have spokes or other features that align within 2į of sunrise at the summer solstice. They also tend to point to the rising places of Aldebaren, Rigel and Sirius. The ages of these wheels are almost completely unknown. Medicine wheels in Canada are theorized to have been built by different peoples over a long period of time. The most elaborate structures appear to have astronomical associations.

The Wichita Indians of Kansas had structures, known as council circles, that were unique to Great Plains archaeology. They are the main feature at five sites. Consisting of a central mound surrounded by a ditch, most are situated on a ridge with a clear view of the horizon. An observer positioned strategically at one circle could see other circles, as well as the winter solstice sunrise. Another position revealed the summer solstice sunset on the horizon. Human bones have been discovered at two sites. Their presence may suggest that sacrifice was included in a ceremony held at the time of the solstice. The Pawnees of Nebraska are known to have sacrificed a female captive during their Morning Star ceremony, held in summer, and usually when Mars rose in the east. The ritual was meant to ensure fertility and successful crops. This event may have been a solstice ceremony, since a version without the sacrifice was performed at the time of the winter solstice. The Pawnees' earth lodge was sometimes used by the priests to observe the positions of the stars and constellations through the door and smokehole. Observations of the sky guided the timing of ceremonies for a people who had no calendar but who did recognize a ceremonial year. Their year began with the First Thunder ceremony, around the spring equinox, and the evening star was significant. If past years were referred to at all, they were linked to an unusual event.

The Pueblo Indians of New Mexico, also known as the Anasazi, used a variety of artificial and natural structures to observe horizon positions of the Sun in order to determine ceremonial and agricultural dates. The Sun also played a role in the ceremonies themselves to lend additional drama. Two possible solstice markers and one possible equinoctial marker have been identified in Chaco Canyon. At Casa Rinconada there is a structure with two sets of wall niches and a window. Sunlight shining through the window illuminates a specific niche for four or five days at the summer solstice. The building's geometry appears to be an attempt to reflect celestial phenomena. A building at Pueblo Bonito has several corner doorways which are rare in Anasazi architecture, and may have been intended for astronomy. At least two doorways permit a view of the winter solstice sunrise. It has been speculated that they may also have been used to time rituals. A third site in the Canyon, Hovenweep, features towers with small openings suitable for observing not only the Sun but also bright stars, notably, Sirius, Vega and Arcturus. This site is the first clear example in the Southwest U.S. of stellar observatories.

Two natural structures in Chaco Canyon are also believed to have been used to watch the sky for the purpose of determining the solstice. Wijiji and Penasco Blanco are both said to have been perfect for viewing the winter solstice sunrise. The former site features a natural rock chimney only a few minutes of arc narrower than the apparent diameter of the Sun, while at the latter site, the edge of a cliff face could have been used as a solar marker. A Sun glyph, or rock painting, has been identified at both sites. Also at Penasco Blanco, a pictograph of a crescent and star configuration was discovered on the cliff wall above the Sun symbol. It has been theorized that this pictograph could represent the Supernova of AD 1054.

Possible records in the Western Hemisphere of this Supernova number more than 15, and include sites in Arizona, Baja California, New Mexico, Texas, and Utah. The case for rock art representations of the Supernova is circumstantial. A major obstacle is lack of accurate dates for the sites. Tree ring dating of logs used to construct Village of the Great Kivas, New Mexico, place the pueblo in the early 11th century. The petroglyph at Capital Reef National Park, Utah, is from the Fremont Culture region; the nearby area was believed inhabited at the time of the Supernova. Finally, the pictograph in Baja California is from a region known as the Great Mural heartland, whose art is characterized by depictions of real objects, almost to the exclusion of abstract symbols. Furthermore, representations of Ďcrescentsí are rare in rock art. Therefore, their appearances are likely depictions of unusual events. The pictograph could represent the crescent Moon and Venus. Morning and evening stars were and still are important deities in Puebloan mythology, but it is unclear if they were portrayed in rock art. One theory is that the tradition of associating the Moon and morning or evening star began with the appearance of the Supernova.

Moving to the eastern U.S., the Seneca Iroquois mark the day by the Sun's highest position. The beginning and ending of the day is midway between two noons. Meridian noon divides the day into two parts with very different natures, which affect most of their ceremonial practices. Almost everything can be defined as being appropriate before noon, the time of day considered sacred, or after noon. Ceremonies in the fore noon, which vaguely begins in the pre-dawn and ends when the Sun passes the zenith, include most public rituals or thanksgiving rituals. Afternoon, that is evening, ceremonies include most medicine rituals. The Iroquois did not traditionally recognize the week. The month was determined by observing the Moon. The year was divided like the day, with an emphasis on middles; it vaguely began around winter solstice. Distinct seasons, associated with traditional activities in hunting and agriculture, as well as ceremonies mark the year. Yearly ceremonies are determined by observing the stars and the Moon's phases. For example, the time of the Midwinter ceremony is set for the full Moon following the rise of the Pleiades, and is slightly reminiscent of the way we set Easter. Summer is marked by the Green Corn ceremony.

Sunrise is a time of great importance to a ceremony of the Mescalero Apache of New Mexico. The ceremony is performed over several days and approaches a conclusion during the last night, culminating in the rising Sun. Songs are sung throughout the last night and must be timed to "pull" the Sun up. The timing is accomplished chiefly by Arcturus, stars of the Big Dipper, and Capella, with Spica, Saturn, Mars and the full Moon playing minor roles. Mountains visible on the horizon from the ceremonial site make the timing by these celestial objects possible. Arcturus sets one hour before timing begins with the Big Dipper. Alkaid, a star in the Dipper, moves 10į each hour and provides an accurate clock. Other stars in the Dipper "set" behind the mountains between 10:30 p.m. and 4:30 a.m. Capella's position at 4:00 a.m. cues the singers to paint Sun symbols on their hands. An hour after the Sun rises, it is drawn by the singers into the ceremonial arena where it shines on the Sun symbols on their hands. The entire round of songs must be sung or the ceremony is incomplete. If the songs are mis-timed during the night, the Sun will already be up before its rays can strategically fall into the arena. Without the mountains on the horizon, the circumpolar Big Dipper could not be used to time this ceremony. Either other celestial objects would have to be used to measure the songs, or the ceremony would have to be held at another site. The natural setting and an awareness of objects in the sky come together to produce a dramatic event.


LECTURE NOTES: "THE FATE OF THE EARTH" BY DR. SCOTT TREMAINE

PREPARED BY DOUG PITCAIRN

Thursday, November 9, 1995
Theatre A, Burke Education Building
Saint Mary's University

That evening, I had the pleasure of attending another lecture presented by the Visiting Speakers Committee of Saint Mary's University. Dr. Scott Tremaine is the Director of the Canadian Institute for Theoretical Astrophysics, a national research institute at the University of Toronto. Here is a summary of his main points.

If we ignore the various ways mankind might cause a major ecological catastrophe, we find that the greatest risks to our precious planet in the long term are astronomical in nature. These can be roughly divided into four possible areas of concern. To help understand the long time frame for these discussions, Dr. Tremaine introduced a compressed time scale where the age of the Universe (assumed to be about 13 billion years) equals one day, and each second counts as 150 thousand years. See the included table.

The first thing is the consistency of our star's output. Astrophysical theories regarding stellar evolution, especially the evolution of dwarf stars such as the sun, are very well developed. Thus we are confident that our star will remain relatively stable for many more millions of years. However, the slow but steady increase in the Sun's output in response to the increasing amount of helium in the core will eventually mean the Earth suffers the same fate as Venus. In our compressed time scale, this will render the Earth uninhabitable by 7 AM the next morning, and by 3 PM, the sun will have swollen to almost the Earth's orbit. If we have survived to this point, we would have to deal with Earth surface temperatures over 1000 Cį!

The second threat to our planet's ecology is the possibility of instabilities in the Earth's orbit. Our planet is held in a tug of war between the Sun, Jupiter and to a lesser extent, all the other planets. Even Sir Newton suspected long term instabilities might develop in planetary orbits. (He found no cause for alarm, however, as he believed God was watching and would merely intervene and set things right again.) Modern computations suggest that this is not a problem, at least not for a very long time. It appears that the planet Mercury is the only planet to get into trouble over the next two billion years. Planets the size of the Earth are quite stable in their orbits. An interesting sideline to this research was that it revealed that the early solar system may have held thousands of moon sized and smaller bodies, which would have been either ejected, or swallowed up by larger planets long ago.

A third danger to life on Earth would be a possible change in the planet's obliquity, or axle tilt. It appears that our planet's axle tilt is a result of complex dynamic forces between the earth, moon, sun and the other planets. Again, modern computer calculations suggest that although the Earth will eventually tilt over as far as 60į, the time frame for this catastrophe is on the order of billions of years, or 4 hours or so in our compressed scale.

The fourth and most pressing concern is the possibility of a collision between the Earth and another body, say an asteroid or a comet. The destructive force unleashed on our world would be considerable, and as we suspect has happened in the past, the ecology of the planet would be severely mauled. The accompanying chart plots the expected rate of asteroid/meteorite collisions with the Earth. Note that bodies with energies of a million megatons or more are expected something like every hundred thousand years. These size objects present humankind with a very real threat. Dr. Tremaine pointed out that using the methods of calculating "lives per year" lost, as an insurance company would, then asteroid impacts are just as dangerous to mankind as are airplane crashes. This led Dr. Tremaine to conclude that perhaps we should be spending as much effort and dollars on preventing asteroid impacts as we currently are on airline safety measures.... makes sense to me.


Go back to this issue's
front page.
Last Updated: December 8, 1995 by David Lane, President, Halifax Centre.