November 2010 Meeting Notes
Several business items were addressed this month, including payment of dues by all members during November, our Logo Contest winner, plans for a visit to the ACT observatory and development of an observing schedule for both public and private observing sessions through 2011. John Grismore gave a brief "Introduction to Celestial Coordinates", and Virgil Reese presented a fascinating program on Exobiology.
Introduction to Celestial Coordinates - John Grismore
Using a desktop planetarium program, John demonstrated the basic features of the horizon coordinate system and the equatorial coordinate system. The horizon system provides a convenient, observer-centered method of locating positions in the sky, with azimuth running from 0 (true north) to 360 degrees around the horizon and altitude going from 0 at the horizon to 90 degrees at the zenith. Any point on the sky can be described by the combination of altitude and azimuth. But unfortunately, as the stars and planets move across the sky, their altitude and azimuth coordinates are constantly changing, making it more difficult to describe their exact position at any moment in time.
This is where equatorial coordinates are especially useful. These coordinates can easily be visualized by imagining the latitude and longitude grid on the Earth's surface being projected onto the celestial sphere. Latitude then becomes Declination in equatorial coordinates, and Longitude becomes Right Ascension. This equatorial grid is fixed to the celestial sphere and rotates with the stars and planets as they move across the sky during the night. Therefore, any object in the sky can be located at any time with a fixed combination of Right Ascension and Declination coordinates. These are the coordinates used on star charts, telescope setting circles and Go To scopes.
Exobiology - Virgil Reese
The possibility of life elsewhere in the universe is a topic full of compelling questions and endless speculation. Over time, as our understanding of the fundamental interactions that drive the processes of life has expanded dramatically, and our insights about the mechanisms of evolutionary development have deepened, investigations into the likelihood of exobiology have become more refined and realistic. Discoveries of conditions possibly favorable to life within our own solar system, and in recent years, the steadily accelerating rate of exoplanet discoveries, have transformed the study of exobiology from vague speculation into serious scientific research.
Virgil's presentation began with a fascinating exploration of the diversity of life on Earth, demonstrating that evolution has created creatures far more imaginative and bizarre than science fiction. He then established a list of attributes that are likely to be necessary for life anywhere in the universe. Prime among them is some form of heredity, which can make possible both replication and gradual evolution. He came to the tentative judgement that "multicellular life will probably only evolve on planets (or moons) containing liquid water, in stable orbits around stable, long lived stars." However, life, once established, might evolve the tools (such as intelligence) that could enable it to expand into previously uninhabitable environments.
If extraterrestrial life is common in our galaxy, there are several ways that it could occur. It may arise independently when conditions are right. Recent astronomical evidence suggests that planets are very common around stars in the Milky Way and by some estimates, 25% of the stars may have Earth-like planets. Virgil pointed out though, that as far as we know, life only started once in the 5 billion year history of the Earth. One possibility is that life arises independently all of the time, but that these newcomers are invariably unable to compete against earth's already established organisms. Another possibility is that life is much harder to start than we would like, and beyond the Earth it may be very rare. Various hypotheses for life spreading from star to star (panspermia) have been invoked to offer the hope of more widespread extraterrestrial life, but all of these have significant problems. In addition, they bring us face to face with the Fermi Paradox. If life has spread throughout the galaxy, we should be able to detect signals from intelligent civilizations. Why haven't we?
The thrust of Virgil's presentation was to investigate the likelihood of life that has evolved to a civilization with spacefaring capabilities, since without this, all life is confined to its own stellar system and will disappear at the end of its star's life. His conclusion is that the most likely explanation for our failure to detect such signals is that the probability of life developing elsewhere in the galaxy is quite low.
The program was fascinating and thought provoking. Discussion was lively and enthusiastic, and didn't stop until the library kicked us out of the meeting roomed and closed for the night.
Monday December 6, John Grismore will present "Observing Asteroid Occultations", in the Bartlesville Public Library Meeting Room. For more information, see the meeting announcement on our website home page at <http://sites.google.com/site/bartlesvilleastronomyclub/> .
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