In the absence of President Bernie Zelazny, Vice President John Bell called the meeting to order at 7:30 PM in 300 Lawrence Hall on the Sul Ross Campus.  There were 15 people present.

       Betty Grimm submitted the following treasurer's report:

        Beginning with a "warm-up" quiz John asked, among other things, whether an astronomical unit was (a) shorter than a light year, (b) longer than a light year, or (c) a measure for comparing the brightness of stars.
        Early measurements of astronomical distances began with measurements of the size of the earth, a necessary step in determining the distance to celestial objects.  In the 3rd century BC, Eratosthenes knew that at noon on the summer solstice, an observer could see the image of the sun reflected in the water in a well near Aswan in southern Egypt.  At the same time, near Alexandria in northern Egypt, the sun made an angle of about 7 degrees with a vertical stick.  Since there are 360 deg in the circumference of the earth, Alexandria is about 1/50 of that distance north of Aswan.  Thus, the circumference of the earth is about 50 times the distance between Aswan and Alexandria.  Eratosthenes measured that distance in stadia, related to the size of an ancient stadium.  Since the size of a stadium is somewhat uncertain, it is not entirely clear how closely Eratosthenes measured the size of the earth [estimated errors range from about 1% to 17%].  Nevertheless, his method was fundamentally sound.
        Aristarchus later measured the distance to the moon by triangulation from the ends of a long baseline on the earth.  Knowing the lunar distance then made in possible to find the distance to the sun.  When the moon is exactly half lit, the lines from the earth to the moon and from the moon to the sun make a right angle.  The angle between the earth-moon line and the line from the observer to the sun is then measured.  The distance from the earth to the sun is then found by trigonometry.  Aristarchus found the earth-sun distance to be about 5 million miles, a gross underestimate because of measurement difficulties, but a huge distance compared with any measurement on the earth.
        In the 19th century, Bessel made the first measurements of the distance to a star, 61 Cygni.  As the earth moves through its orbit, the apparent positions of the nearer stars change in relation to the more distant stars.  This apparent motion is called parallax.  If you hold a finger at arm's length in front of you and switch from one eye to the other, you will see your finger apparently move in relation to more distant objects, a down-to-earth example of parallax.  Parallax can be used to find the distance to stars located within a few hundred light years of the earth.  If we know the size of the earth's orbit, then we can find the distance to the nearer stars by measuring parallax, in effect using the astronomical unit (the distance from the earth to the sun) as a baseline for triangulation.  Parallax measures give rise to the parsec as another distance measure equal to 3.26 light years, the distance at which the earth-sun distance, or one astronomical unit, subtends an angle of one arcsecond.  Really great distances are measured in megaparsecs.
        Distances to other galaxies are found principally using spectroscopic observations of the red shift.  Using the 100-inch scope at Mt. Wilson, Edwin Hubble in the 1920s found that more distant galaxies show progressively greater red shifts out to distances of billions of light years, a light year being about 6 trillion miles.  Thus, by measuring the shift of the spectral lines of known elements, we can find the distance to galaxies.
        John showed a video of a short movie entitled Powers of Ten by Charles and Ray Eames, a prominent husband-wife pair of industrial designers.  The movie showed a scene on the earth's surface as the observer moved away by successively greater distances, starting at 1 meter, then 10, then 100, and so on.  Beginning with a man lying on a blanket in the Chicago area, we soon lost sight of the man as we saw a wider and wider area of the earth's surface.  Soon we saw the entire earth, then the solar system, then our Milky Way galaxy, and eventually uncounted galaxies in the universe itself.  The movie also showed what we would see moving closer by powers by ten, from 1 meter to 0.1, 0.01, 0.001, and so on through submicroscopic distances.  Changing our viewing distance by powers ten causes enormous changes in what we see.
        Many thanks to John for another informative presentation.

        Current predictions for the number of potentially dangerous asteroids have been under-estimated by at least 20%, say astronomers. According to recent estimates, there are between 750 and 900 asteroids circling the Earth with the potential to cause devastation on impact.
        But a researcher at the US-based Massachusetts Institute of Technology (MIT) says these predictions should be revised upwards, on the basis of new data.
        Scott Stuart believes there are more than 1,100 objects within our Solar System that could come close to Earth.
        The new number is consistent with earlier estimates made by the late Eugene Shoemaker, who based his analysis on the number of asteroid impact craters on the Moon.

        The annual Leonid shower will occur on November 17-18. Despite strong moonlight, two predictions argue for hundreds of Leonids per hour on the morning of 11/17 (UT) 5:17 AM CST, favoring North America.  Have a look if you're up at that hour of the morning.

If we have not yet received your dues, then please use the convenient envelope addressed to our treasurer that is included with this copy of your Newsletter.

Betty Lou Grimm, Treasurer
Big Bend Astronomical Society, Inc
1001 N 2nd Street, Apt F-22
Alpine, TX 79830