charles hakes fort lewis college1. charles hakes fort lewis college2 introduction the celestial...
TRANSCRIPT
Charles HakesFort Lewis College 1
Charles HakesFort Lewis College 2
Introduction
The Celestial Sphere
Charles HakesFort Lewis College 3
Outline
• Lab notes• Review• Observing the Sun• Unit Conversions• RA/Dec• SETI
Charles HakesFort Lewis College 4
Notes
• Homework 1 due on Friday. • Sun lab(s) due in “box”:
• Noontime Sun by next Friday 5:00• Sunset part1 by next Friday 5:00
• Lab Resources Part B next week.• Binocular lab next Mon,Thur (?)
Charles HakesFort Lewis College 5
Observing the Sun
• http://sunearth.gsfc.nasa.gov/eclipse/SEhelp/safety2.html
• http://www.mreclipse.com/Special/filters.html
Charles HakesFort Lewis College 6
Measuring Angles
• A fist at arms length is about 10°• Fingers spread wide are about 15°• Three fingers together are about 5°• One pinky width is about 1°• The full moon is almost exactly 0.5°
Charles HakesFort Lewis College 7
Dimensional Analysis
• Dimensional Analysis is VERY helpful in problem solving.
• Check your equations with specific units.• Velocity example - how do distance (x), time (t),
and Velocity (V) relate?
V = x/t
Charles HakesFort Lewis College 8
Dimensional Analysis Example - Which equation is correct?
A) velocity = distance * time
B) time = velocity * distance
C) time = distance / velocity
D) time = velocity / distance
Charles HakesFort Lewis College 9
Which equation is correct?
A) velocity = distance * time
B) time = velocity * distance
C) time = distance / velocity
D) time = velocity / distance
Charles HakesFort Lewis College 10
Velocity Exercise
• The laser travels 9.6m across the room. How many seconds does it take?
Charles HakesFort Lewis College 11
Light Travel Time Across the Room (9.6 meters)
A) 2.9x106 sec
B) 2.9x10-6 sec
C) 3.2x10-5 sec
D) 3.2x10-8 sec
Charles HakesFort Lewis College 12
Light Travel Time Across the Room (9.6 meters)
A) 2.9x106 sec
B) 2.9x10-6 sec
C) 3.2x10-5 sec
D) 3.2x10-8 sec
Charles HakesFort Lewis College 13
Conversion Factors
• Conversion factors are equivalence statements expressed in the form of ratios
• Example: 1 in = 2.54 cm• Conversion factors let you express a
quantity in terms of other units without changing its physical value.
Charles HakesFort Lewis College 14
Conversion Exercise
• Convert 0.61 m to inches.
Charles HakesFort Lewis College 15
How many inches is 0.61m?
A) 0.24 inches
B) 1.56 inches
C) 24.0 inches
D) 156 inches
Charles HakesFort Lewis College 16
How many inches is 0.61m?
A) 0.24 inches
B) 1.56 inches
C) 24.0 inches
D) 156 inches
Charles HakesFort Lewis College 17
How many light years was that 9.6 m?
A) 9.1x1012 ly
B) 1.0x10-15 ly
C) 2.9x109 ly
D) 1.1x10-14 ly
Charles HakesFort Lewis College 18
How many light years was that 9.6 m?
A) 9.1x1012 ly
B) 1.0x10-15 ly
C) 2.9x109 ly
D) 1.1x10-14 ly
Charles HakesFort Lewis College 19
Significant Figures
• Example• 4.56 has three significant figures.• 4.56x106 also has three significant figures.• .000456 also has three significant figures.
• A calculation output can not have more significant figures than the input.• If an equation has a whole number (for example 2) it is
considered to be 2.00000 etc.• Calculation hint - it is often best to keep all available
figures until the last step, and then round your answer.
Charles HakesFort Lewis College 20
Scientific Notation
• What does 1.0x106 mean?• Positive exponents mean shift the decimal place to the
right (bigger numbers).• Negative exponents mean shift the decimal place to the
left (smaller numbers).• Usually only have one digit to the left of the decimal.• Most calculators have a single key to add the (x10^)
term. (EXP, EE)
Charles HakesFort Lewis College 21
Measurements
Multiple Prefix
109 giga-
106 mega-
103 kilo-
10-2 centi-
10-3 milli-
10-6 micro-
10-9 nano-
Charles HakesFort Lewis College 22
Algebra Hint
• The following relationship will be useful to remember:
Charles HakesFort Lewis College 23
Introduction
The Celestial Sphere
Charles HakesFort Lewis College 24
Oslo, Norway is 60°N latitude. What declination line passes through the zenith in Oslo?
A) 0°
B) 30° N
C) 60° N
D) 90° N
Charles HakesFort Lewis College 25
Oslo, Norway is 60°N latitude. What declination line passes through the zenith in Oslo?
A) 0°
B) 30° N
C) 60° N
D) 90° N
Charles HakesFort Lewis College 26
Astronomy Picture of the Day
http://antwrp.gsfc.nasa.gov/apod/ap080922.html
Charles HakesFort Lewis College 27
The Celestial Sphere
• Locations to note• North celestial pole• Celestial equator
• Declination corresponds to latitude. • Right ascension corresponds to
longitude. • RA and Dec are “fixed” onto the
celestial sphere.
Charles HakesFort Lewis College 28
Figure P.4Right Ascension and Declination
Charles HakesFort Lewis College 29
Declination
• Declination corresponds to latitude. • Units are degrees (and minutes and
seconds). • Durango’s latitude is +37.275° N.
The declination line passing directly overhead is also +37.275° N.
Charles HakesFort Lewis College 30
Oslo, Norway is 60°N latitude. How high does the star Polaris appear?
A) 0°
B) 30° N
C) 60° N
D) 90° N
Charles HakesFort Lewis College 31
Oslo, Norway is 60°N latitude. How high does the star Polaris appear?
A) 0°
B) 30° N
C) 60° N
D) 90° N
Charles HakesFort Lewis College 32
What is the southernmost declination line visible from Oslo (at 60° N)?
A) 60° N
B) 30° N
C) 0°
D) 30° S
Charles HakesFort Lewis College 33
What is the southernmost declination line visible from Oslo (at 60° N)?
A) 60° N
B) 30° N
C) 0°
D) 30° S
Charles HakesFort Lewis College 34
Standing on the equator, you can see…
A) the celestial equator directly overhead
B) entire celestial sphere during a 24 hour day
C) both celestial poles on your horizon
D) all of the above
Charles HakesFort Lewis College 35
Standing on the equator, you can see…
A) the celestial equator directly overhead
B) entire celestial sphere during a 24 hour day
C) both celestial poles on your horizon
D) all of the above
Charles HakesFort Lewis College 36
Durango’s latitude is 37.275° N. What is the southernmost declination line visible?
A) 0°
B) 37.275° S
C) 52.725° S
Charles HakesFort Lewis College 37
Durango’s latitude is 37.275° N. What is the southernmost declination line visible?
A) 0°
B) 37.275° S
C) 52.725° S
Charles HakesFort Lewis College 38
Right Ascension
• Right Ascension corresponds to longitude. • Units are Hours (and minutes and seconds).• The trick (as with longitude) is to decide on
the zero point.• Longitude zero is at the observatory in
Greenwich England.• RA zero is where the sun crosses the
celestial equator going north.• RA is always moving w.r.t. longitude.
Charles HakesFort Lewis College 39
PRS question
• How long is the following exposure?
Charles HakesFort Lewis College 40
Figure P.3The Northern Sky
Charles HakesFort Lewis College 41
How long is the exposure? Enter the correct number of hours.
A) 4
B) 5
C) 6
D) 7
E) 8
Charles HakesFort Lewis College 42
Three Minute Paper
• Write 1-3 sentences.• What was the most important thing
you learned today?• What questions do you still have
about today’s topics?