Prologue
Far away from the city lights and driving deep into the desert at night, one can see the immense blanket of stars and celestial objects that have accompanied the existence of mankind from the earliest of times. We cannot know exactly what our early ancestors thought of the incredible wonder that loomed over their heads, but we do know that it did not escape their thoughts, since we see evidence on ancient cave walls and rock art petroglyphs, some within driving distance of Barstow Community College.
During the early civilization building periods of Ancient Sumer, Babylon, Persia, and eventually the Egyptians and Greeks, intricate drawings were made that charted the heavens with supposed outlines of various animals, both real and mythical, and a plethora of deities. It has not escaped the notice of some archaeologists that several of the earliest grandiose structures of early civilizations, both in the Old World and in the Americas, were designed as laboratories or platforms for charting the heavens and gazing even closer into the wonders of the night sky. In fact, The University of Leicester, in England, has recently appointed a full time professor whose specialty is Archaeoastronomy, which means the study of ancient civilizations that devoted their lives to analyzing celestial bodies, and the platforms that they left behind.
In modern times we have commonplace knowledge of celestial objects on the nightly news, along with space exploration, space shuttles, International Space Stations, and the latest from the Hubble Telescope, virtually 24/7. Amazingly, the general public’s interest in Astronomy has actually INCREASED during this time, instead of becoming "boring," mundane, or "overexposed." Humankind’s ultimate sublimated goal may be to DISCOVER WHAT IS OUT THERE, and to question how it all came into being. That goal is essentially the purpose of THIS class, so let the journey begin…
LECTURE ONE
AN EARTH CENTERED UNIVERSE:
If you were a girl scout or boy scout in your youth, or if you went camping with your folks, you could not have failed to notice the "Big Dipper" or "Little Dipper" and reacted with astonishment. Actually, the "Big Dipper" is a portion of the Constellation Ursa Major, one of several constellations that intrigued early civilizations. A constellation is defined as an "area of the sky which contains a pattern of stars named for a particular object, animal or person." Some common constellations that are household names today, include, Canis Major, Taurus, Leo, Orion, and Draco. One of the "downsides" of urban life is that city lights, air pollution, and tall buildings now block our night time viewing opportunities of the constellations, something that people in centuries prior to this one, took for granted. No doubt your own grandparents or great grandparents had an excellent knowledge of objects in the night sky, since their era had much more time available (prior to television and HDTV) and cleaner, less obstructed skies to view, particularly if they lived on a farm or at some distance from the city.
SOME BASICS
Consider the earth as a basketball. Now slice it in half. The top half is called the NORTHERN HEMISPHERE. The bottom half is called the SOUTHERN HEMISHERE, and the slice is called the EQUATOR. If you have ever lived in South America or Southern Africa, your sky viewing will be quite different from someone who has lived in Minnesota or perhaps Alaska!
Your textbook notes that ANGULAR SEPARATION
"is the angle between lines originating from the eye of the observer toward two objects."
Angles are measured in degrees.
If you get up at dawn the sun is located at nearly 0(zero) degrees on the horizon, and obviously changes (increases) its angle as the day wears onward. ALTITUDE is" the height of a celestial object measured as an angle above the horizon." Thus, the sun (in summer months) is directly overhead (its ZENITH point) at an angle of 90 degrees at high noon! (at least in the Northern Hemisphere).
A SUMMARY OF THE CHAPTER :
In this chapter we have learned that the earth was considered the center of the universe to many early cultures. Later the Helocentric view became dominant illustrating that the Sun was the center of the universe. Today we know that there are thousands of "suns" similar to our own and that there are numerous constellations with objects similar to our sun. The following is an outline of the chapter one.
INSTRUCTOR’S LECTURE ON THE MATERIAL OF CH. ONE:
The Celestial Sphere: Just as the earth could be cut in half like a basketball, so it seems the starry heavens (celestial sphere) can be divided into the North Celestial Sphere (rotating above the North Celestial Pole) and the South Celestial Sphere (rotating above the South Celestial Pole). The night time sky at each location is distinctly different, as one might imagine, since they are quite different viewing platforms.
Constellations: The agreed upon number of constellations is 88, the early Greeks were amazing in that they recognized nearly half of that number! The Ancient Egyptians were no less slack in their Astronomical observations, they even believed that the Ancient Mummified Pharaohs were associated with Orion and would make a nightly journey back to Egypt from the heavens to counsel the high priests. Some researchers have even postulated that air vents and long forgotten shafts in the Pyramids of Giza were designed to be aligned with the stars of Orion’s Belt (although this hypothesis has not been validated).
Celestial Coordinates: GPS handheld systems or even basic compass navigation on earth helps to determine latitude and longitude through an imagined grid system. In the same manner, astronomers use a grid system for the heavens, using declination and right ascension.
Sun’s Motion Across the Sky: This may come as a shock to those of you who work the "graveyard shift," or to those of you who may live in Astoria, Oregon (the city with the least amount of sunny days in the USA), but the sun comes up in the east and goes down in the west. So does the moon. So, it appears, do the celestial spheres.
The Ecliptic: The apparent path that the Sun takes among the stars is the ecliptic, according to your textbook. This "curvy orbit" some have called it, seems to wander North of the celestial equator (an imaginary line above the actual equator that can be thought of as ‘written in the skies’) at the summer months of the year and then wanders South during winter months.
The Sun and Seasons: Our Sun has a lot to do with temperatures on earth (of course!). Not only does it bring diurnal changes (day time to night time fluctuations) of temperatures, but it affects the seasons as well. Bitter cold winter months in Wisconsin happen at the same time as blazing hot temperatures are occurring in South America and South Africa. Even the rare "sun spots" which are cyclical, periodic explosions on the surface of the Sun itself, seems to cause changes in our planets weather and atmospheric conditions.
Some Famous Astronomers of the Past:
Aristotle = The Earth is the center of the universe and the Sun revolves around our planet!
Aristarchus = Conversely believed that the Earth revolved around the Sun.
Copernicus = Favored the "heliocentric" theory which saw the sun as the center of the solar system.
Kepler = Noted that our planets move in ellipses.
Galileo = Considered a heretic for examining the heavens with a telescope and thereby discovered the moons of Jupiter and other oddities not accepted by the Church.
Newton = Brilliant Physicist examined laws of motion and gravity which held until the "Einstein Revolution" in physics.
Einstein = Brilliant Physicist who lead science into the relativity age and examined gravity resulting from curvature of space-time.
Herschel = galaxies are a vast collection of stars (like our own sun).
Hubble = The universe is constantly expanding.
Shapley = Notations of our location in the galaxy and its shape.
Science is all about changes, and as one might observe from the list above, there was a considerable amount of change taking place in the theories and explanations of the universe from the earliest times until the present.
Your textbook chapter homework is next. Go to the link below and log onto the objective test (multiple choice) for Chapter One. Take the test and then send the results to my email box. I will record your score and send you my comments concerning your chapter homework.
Regards,
Dr. Akers
Your discussion question is the following:
"Pick two astronomers who have made a significant contribution to the Science of Astronomy. Compare and contrast their views in a short answer essay format."
 |
 |
 |
 |