1. Astronomy 1020: Stars, Galaxies and the Universe
Prof. Paul J. Wiita
Rm 715, One Park Place,
Phones: (office); (cell)
URL: (syllabus, summaries of notes)
Assignments on Mastering Astronomy: with course ID MAWIITA1020F09
Labs: in 516 Kell Hall
80131: Mondays, 9:00-10:50 AM
80132: Tuesdays, 11:00 AM-12:50 PM
80133: Fridays, 9:00-10:50 AM

2. What will we study? Astronomy = star + knowledge
We examine stars, galaxies & cosmos.

3. How do we learn anything about the Universe?
The Scientific Method
How do we learn anything about the Universe?
We will frequently refer to the concepts of the Scientific Method, and even when we don’t, you should be thinking about how it applies in each part of the course (and throughout your life!).
The key element is curiosity!
I hope your previous studies haven’t completely eliminated that characteristic from your personality.

4. The First Steps in the Scientific Method
Observe: use your senses or augmentations of them (microscope or telescope) Example: the sky is blue.
Hypothesize (come up with a possible explanation of the observation).
Someone has painted it blue Blue light is more easily scattered than red in the atmosphere, so the blue sky is scattered sunlight.
3. Test HYPOTHESIS through a PREDICTION If the latter is true, then if sunlight passes through more of the atmosphere, the sun should lose green and yellow light too and appear red (When does this happen?)

5. Blue light scatters more in the atmosphere
Off molecules (strongly) and off dust (less so, however).

6. Testing Hypotheses 4a. perform EXPERIMENT
4b. OR make new OBSERVATION Sun is indeed red/orange near dawn and dusk
5a. If in agreement, perform new test (and keep doing so).
5b. If in disagreement, discard or modify hypothesis
GO BACK TO STEP 2!
Only if MANY tests are passed can a HYPOTHESIS be called a THEORY.
If the THEORY applies in a wide range of situations, it may be raised to the status of a LAW (e.g., Newton's LAW of Gravity)

7. In SCIENCE nothing is ever PROVEN
STILL, even a LAW can be wrong (or partly right):
Einstein showed that Newton's Laws don't hold exactly if:
velocities are close to the speed of light (special relativity) OR if
lots of mass is concentrated in a small volume (general relativity).
SO NOTHING IN A REAL SCIENCE IS EVER ABSOLUTELY PROVEN TRUE, although most of what is discovered and tested in a "hard" science is VERY LIKELY to be correct.

8. Types of “Hard” Sciences
Categorize: astronomy, biology, chemistry, geology, medicine, meteorology, oceanography, physics as
OBSERVATIONAL or EXPERIMENTAL sciences.

9. The REAL Scientific Method
But the preceding is idealized.
In reality, even good scientists often don't discard hypotheses when they fail an experimental or observational test.
Why not?
A. Experiment is wrong.
B. Experiment is misinterpreted.
C. Psychological/sociological/political difficulty in giving up long-held beliefs.
Eventually the weight of evidence becomes overwhelming and there is a PARADIGM SHIFT or SCIENTIFIC REVOLUTION (e.g., Copernican, Darwinian, Quantum Mechanics)

10. Characteristics of Sciences
The above are characteristics of ANY SCIENCE.
The key point: scientific results are falsifiable.
If they cannot eventually be tested, they fall outside the realm of science and enter philosophy, religion, etc.
Pseudo-sciences do not allow themselves to be tested and “true believers” refuse to consider strong evidence against their validity. Examples:? 
astrology, alchemy, numerology, palmistry, crystal/pyramid power

11. What A Science Must Have

12. Types of Sciences
What about: anthropology, economics, history, political science, psychology, sociology?
These social or "soft" sciences rely to one extent or another on scientific methods, but also invariably carry a great number of preconceptions that allow for many disparate interpretations to be drawn from the same data.
In the natural or "hard" sciences, the range of “allowed” interpretations is usually much less.
Start here on Thurs 8/24

13. Astronomy vs. Astrophysics
Aside from the OBSERVATIONAL - EXPERIMENTAL dichotomy, since the advent of calculus we have distinguished these approaches from THEORETICAL science, driven by applied mathematics.
ASTRONOMY IS AN OBSERVATIONAL SCIENCE.
ASTROPHYSICS IS AN OBSERVATIONAL -THEORETICAL - EXPERIMENTAL SCIENCE.
Today we typically use these terms interchangeably since so much of what we learn combines observations with theory and some experimental work (laboratory astrophysics).
We also must consider COMPUTATIONAL science as a (nearly) equal partner.
Start here on Wed 8/22.

14. Review of Scientific Notation
102 = 100, 101=10, 100 = 1, 10-1=0.1, 10-2=0.01
1012=1,000,000,000,000=trillion (Tera-)
109 =1,000,000,000 = billion (Giga-)
106 = ,000,000 = million (Mega-)
103 = ,000 = thousand (kilo-)
10-2= 0.01=one-hundredth (centi-)
10-3= 0.001=one-thousandth (milli-)
10-6= =one-millionth (micro-)
10-9= =one-billionth (nano-)
5.4x103=5, x10-3=
4,700=4.7x = 1.7x10-2
Start here on 1/9

15. Powers of Ten Arithmetic
Multiplication:
(5.3x103) x (6x10-5) = 31.8x103+(-5)
=31.8x = 3.18x10-1
= = 0.3
One significant figure! Keep only the minimum number of significant figures going into the calculation in the answer.
Division:
(9.3 x10-4)/(3.10x10-6) = 3.0 x10-4-(-6)
= 3.0 x102
= 300
BUT, 3.0x102 is the better answer, as it CLEARLY has two significant figures; scientific notation is PRECISE.

17. The Scales of the Universe
We deal with the largest possible things -- the whole universe -- and with the smallest -- nuclei of atoms.
This requires us to use a wide range of PHYSICAL UNITS and we USE THE METRIC SYSTEM.
Length: m or cm Mass: kg or g
Time: s or yr Temperature: K(elvins)
ON 1/18/05 START w/ SLIDE 8 SEASONAL VARIATIONS
Radius of Sun = 6.96x10^10cm = 7x10^5 km
Mass of Sun = 1.989x10^33g = 2x10^33g = 2x10^30 kg
One year = 31.5x10^7 s
1 pc = 3.26 light-yr = x 1018cm=3.1x1013km
1AU = 1.496x1013cm = 150,000,000 km (astronomical unit = mean distance between earth and sun)

18. Sizes of Everything
Universe: open or flat -- infinite; closed cm
Galaxies: no of stars ; size ~ 1023cm~3x104pc
Stars: cm (most radii)
Typical separations: 1018cm ~ 1 pc
Planets: RE=6.4x103km = 6.4x108cm
Separations: ~ 1 AU
Mountain: Tallest ~ 10 km, more typical ~6 km Hm/RE=6.4km/6.4x103km=1.0x10-3
People: 1.5m = 1.5x102cm (~5 feet)
Visible light: wavelength=500nm=5x10-5cm
Atom: 0.1nm=10-8cm=10-10m (X-ray wavelength)
Nucleus: 1 Fermi = 10-13cm = 10-15m
Zoom: Universe to You
Write math symbols for >, >=, equivalent, approx equal, proportional, roughly equal

19. Time Scales of the Universe
Time since the Big Bang: ~1.4x1010 yr
Galaxies formed: ~1.3x1010 yr ago
Solar system formed: 4.55x109 yr ago
Oldest rocks on Earth: 3.8x109 yr BP
Earliest life forms: ~3.5x109 yr BP
Earliest hominids:~2x106 yr BP
Mountains: Appalachians:~2.5x108yr BP; Rockies: 7x107 yr BP
Human lifespan: ~75 yr
Oscillation time for visible light: ~2x10-15 s
Time for light to pass the nucleus of an atom: ~3x10-24s

20. Astronomy 1020 Lab Requirements Bring to lab next week
Activities in Astronomy, by John W. Wilson
Metric ruler ~ 30 cm long
Protractor
Drawing compass
Scientific calculator (not a cell phone)