Astronomy is the science developed by those who like to stay up late at night, and stare up at the sky
-Anonymous
Let there be lights in the firmament of the heaven to divide the day from the night; and let them be for signs, and for seasons, and for days, and years.
-Genesis 1:14
Besides the obvious technology spin offs from studying space (e.g., cell phones, personal computers) there are more subtle reasons to understand space: our entire biology and culture are ordered around astronomical cycles (dating as far back as the 1st cuneiform records from the Sumerians)
Holidays: combinations or intersections of these cycles (e.g., Easter and Chinese New Year ... or even events occurring once in a blue moon)
Also, our entire modern measurements of time, angles, directions are founded upon the old Babylonian sexagesimal number system.
The summer constellation Cygnus is overhead for Fall students.
Famous winter constellation Orion is overhead for Spring students.
( free Star Charts )
Review angular measurements (pp.11 Chaisson)
Let's go outside ... bring pen and paper
Remember Compass Directions as we return to classroom
Iterate
Lab exercise: Build a scale model of the Earth-Moon system.
Earth ~ desk globe ~ basketball (1 foot diameter)
Moon ~ baseball (3 inches diameter; or 1/4 Earth diameter known from lunar eclipse geometry Fig.1.24)
Earth-Moon orbit ~ classroom (~30 feet; or 120 Moon diameters calculated from rule-of-60)
All scales are approximate; what is important here is to get a intuitive feel for the system.
From class demo, understand differences between solar and lunar, e.g., Which one is more common? Which one one lasts longer?
Note: Next lunar eclipse is Feb 21, 2008 !
Next solar eclipse is August 1, 2008.
Daily: all celestial objects exhibit a roughly 15°/hour E-W motion
(Celestial Sphere, one, two Fig 1.11 Chaisson).
Long Term: In addition, the celestial objects have individually different long-term motions. Relative to the "fixed" background stars we observe the following motions along the Ecliptic:
Summary of naked-eye celestial motions
Summary of main visible planetary motions
Experiment with the Sky View Café virtual planetarium.
*note: as usual for the scope of this class, approximate values are used (e.g., the Sun's angular motion is closer to 0.9863°/day but you need only memorize the approximate value of 1°/day)
28 day period
Recall the 3d class demo we construted. Then use this figure Fig 1.22 Chaisson summarizing what we demonstrated in class.
Exam questions will most likely concern what you would observe during sunrise or sunset. In conjunction with your textbook Fig 1.22 Chaisson this satellite picture of Earth's surface at sunset (or better yet the picture viewed facing South) should help you visualize what's going on.
Chaisson textbook: Chapter 1
Zeilik. Astronomy, the evolving universe, 9th edition
Constellations from UCAR's Windows to the Universe
Nasa's eclipse home page
The Astronomical Picture of the Day (APOD)
Old School tools for knowing the night sky:
New computer tools for keeping up with the night sky:
Document URL: http://www.uh.edu/~jclarage/astr3131/lectures/1/1.html
