1. Astronomy 105 Laboratory
Lab 11

2. AST 105 Review for Lab Exam

3. Ast 105 Lab Exam Week of November 27, at normal lab time. Don’t be late!! Items to bring… - One scantron (882-E) - two pencils

4. Study! About 3-5 questions from each lab exercise Review
Main concepts covered
Procedures and measurements
Questions and calculations
Bring a scantron: 882-E
Review material – Power point slides online

5. Constellations – Sky Familiarization

6. North East South Ecliptic Sun’s Path Celestial Equator Summer Solstice
Vernal Equinox
East
Autumnal Equinox
Celestial Equator
South

7. March 8:00 p.m
North
Zenith
32° X
West Horizon
East
South
Meridian

8. March 7 @ 8:00 p.m not visible East Horizon West Horizon Meridian East

9. Sky Familiarization A Few More Things to Remember
Any vertical line on your SC-1 (north-south) is a meridian.
Approximately one half of the stars on the SC-1 are visible at any given time (12 hours of RA).
Meridian moves eastward 4 minutes each day (Earth’s revolution)
Meridian moves eastward 1 hour of RA for every hour of time (Earth’s rotation)

10. Scientific Measurements

11. Scientific Experiments / Observations
Physical quantities can never be measured with absolute precision

12. How Many Significant Figures
0.089 2
1.089 4
12000 2
12001 5

13. Number Significant Figures Scientific Notation
3.502 x 106
decimal number (1-9)
10 raised to an integer power
Number Significant Figures Scientific Notation
9004 4
9.004 x 103 1
7 x 10-6 43 2
4.3 x 101
7,805,000,000 4
7.805 x 109
0.0408 3
4.08 x 10-2
8.4 2
8.4 x 100

14. (4.0 x 104)(2.0 x 103) = (4.0 x 2.0)(104 x 103) = (8.0) x (104+3) =
To multiply two numbers in scientific notation multiply the decimal parts of the numbers and add the exponents algebraically.
(4.0 x 104)(2.0 x 103) =
(4.0 x 2.0)(104 x 103) =
(8.0) x (104+3) =
8.0 x 107
(6.0 x 102)(2.0 x 105) =
12.0 x 107
= 1.2 x 108

15. Units Provides numerical context for a measurement Unit conversion
Ex. Convert 500 kilometers into centimeters
1000 m = 1 km m = 100 cm
1000 𝑚 1 𝑘𝑚 =1 and 𝑐𝑚 1 𝑚 =1
500 𝑘𝑚× 1000 𝑚 1 𝑘𝑚 × 100 𝑐𝑚 1 𝑚 =5× 10 7 cm

16. The Moon

17. Synchronous Rotation EARTH Does the Moon rotate on it’s axis?
N.P.
Synchronous Rotation
EARTH
N.P.
N.P.
N.P.
Does the Moon rotate on it’s axis?
What is the Moon’s hidden side?
MOON
N.P.

18. Noon Sunset Midnight Sunrise Phase: 1st quarter Rise Time: Noon
N.P.
Phase:
1st quarter
Rise Time:
Noon
Transit:
Sunset
Set Time:
Midnight
N.P.
Noon
Sunset
Midnight
Sunrise

19. Mercury’s Orbit

21. Verifying Kepler’s 1st Mercury’s Orbit Major Axis F F
Equal Time Intervals

22. Verifying Kepler’s 2nd Mercury’s Orbit 10 km AU20 30 40 50 60 70 80 90
100
10 km 6
SUN
Name (print):__________________________________ Section: _____
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0 AU
0.8
110
120
Verifying Kepler’s 2nd
Equal area in equal time.
Mercury’s Orbit
Major Axis

23. Kepler’s 3rd
P2=ka3
Finding the Sun’s mass.

24. Emission Spectra

26. Formation of Emission and Dark Line Spectra

29. The Earth’s Orbital Velocity

30. The Doppler Effect 1 2 3 4 5 Increasing Velocity Increasing Velocity

31. From measured Doppler ShiftVA
Arcturus ?
From measured Doppler Shift
Orbital velocity of Earth
Radial velocity of Arcturus
Radius of the Earth’s Orbit VB o 

32. The HR Diagram

33. Apparent Brightness of Stars
Stellar Luminosity -- Total amount of light energy emitted each second
Surface Area
Temperature
Distance from the Earth

34. Magnitude Stellar Brightness
Apparent Magnitude (mv) - Brightness from Earth
Absolute Magnitude (Mv) - Brightness from 10 pc
Absolute magnitude depends only on a star’s luminosity (the star’s wattage)

35. Spectral ClassificationB

36. HR Diagram -10 -5 The Sun +5 +10 +15 O B A F G K M M=+5 G2+5
+10
+15
Absolute Magnitude
Temperature
The Sun
M=+5 G2

37. The Sun’s Spectral and Luminosity Class: G2 V

38. Which star appears faintest in our sky?mv Mv
Spectral
Type
Luminosity
Class
Aldebaran
+0.9
-0.2 K5
III
Alpha Centauri A
0.0
+4.4 G2 V
Antares
-4.5 M1 I
Canopus
-0.7
-3.1 F0 II
Fomalhaut
+1.2
+2.0 A3
Regulus
+1.4
-0.6 B7
Sirius
-1.4 A1
Spica
-3.6 B1
Which star appears faintest in our sky?
Regulus
Which star has the greatest luminosity?
Antares
Which star has the highest surface temperature?
Spica
Which star is a red giant?
Aldebaran
Which main-sequence star has the longest lifetime?
Alpha Centauri

39. Stellar Parallax

40. Stellar Parallax Motion of Earth cause parallax shifts
Used to find distance to stars out to a few hundred light-years
Parallax is ½ of measured shift
More distant stars have a smaller parallax… a star with ½ the parallax of another star is 2x farther away
d = 1 / p “p” is in arc seconds and “d” is in parsecs

41. The Pleiades

42. Stars in a Cluster Common Properties Distance Age Different Properties
Spectral Types (temperature)
Luminosity Class (size)

43. { Absolute Magnitude Apparent Magnitude
Star Cluster
O B A F G K M
color index
Absolute Magnitude
Main-sequence
HR Diagram
10 pc
Distance Modulus = m - M
The difference between the absolute magnitude and the apparent magnitude can be used to find the distance to a star cluster.   
If m-M > 0 then the distance to the cluster is > 10 pc.
If m-M = 0 then the distance to the cluster is = 10 pc.
If m-M < 0 then the distance to the cluster is < 10 pc.
d >10 pc DM {
color index
Apparent Magnitude
Color-Magnitude
Diagram
d <10 pc
d <10 pc
10 pc
d >10 pc

44. What is the distance to Cluster B?
Cluster A: Distance 50 ly
Cluster B: Distance ?
The apparent brightness of the stars in Cluster B are 4 times fainter than the stars in Cluster A.
What is the distance to Cluster B?
Inverse-Square Law:
√4 = 2
Cluster B is 2 times farther or 100 ly.

45. Ages and Distances to Clusters

46. Interstellar Dust Reddens Light (makes stars appear cooler)
Dims Light (makes stars appear further away)
Interstellar Reddening

47. Pleiades - Open Cluster
Distance ly Age - 60 million years
B6 stars million yrs. MS lifetime
age of cluster = lifetime of stars at main-sequence turnoff point

48. Hubble’s Lab

49. The Universe is Expanding!!
Recessional Velocity is Proportional to Distance
V = 0
2800
2100
1400
700
km/sec
10 Mpc
20 Mpc
30 Mpc
40 Mpc
Milky Way A B C
V = 0
2800
2100
1400
700
km/sec
10 Mpc
20 Mpc
30 Mpc
40 Mpc
Milky Way A B C
Alien’s Galaxy
The Universe is Expanding!!

50. Finding a Galaxy’s Distance Hubble’s Law
Hubble Diagram
v = Ho d
d = v / Ho
To Find Distance:
Measure recessional velocity (red shift)
132 Mpc

51. Sample Galaxies
Distance
images
Recessional Velocity
spectra

52. Hubble Diagram Procedure - plot data - draw best fit line
v = Ho x d
Hubble Diagram x
Procedure
- plot data x
- draw best fit line
rise
- find slope (Ho) x
slope = rise/run x
run x

53. Rotation of Saturn

55. The Doppler Effect: Measuring the Radial Velocity of a Star
Laboratory Spectrum
Spectral Lines Match
Laboratory - No Radial motion
Earth
Distant Star
Radial Velocity = 0
Blueshift
Radial Velocity -
Radial Velocity -
Redshift o 
Radial Velocity +
Radial Velocity +

56. Important: Do not write or mark on the Saturn Handout

57. Spectroscope Slit Light from here shows the largest Red Shift
Light from here shows the largest Blue Shift
No Doppler Shift from this Light

58. V A
Saturn B V
Doppler  o
A
B

59.  (mm) = Top Distance – Bottom Distance
Reference Line
Bottom
 (mm) = Top Distance – Bottom Distance
c = 300,000 km/s
o = 6200 Å

60. Finding the Rotation Period of Saturn
Period = Distance / Velocity V
Distance = Equatorial Circumference = 2R R
Period (P) – Rotation Period
P = 2  R / V
Saturn

61. The End

63. Lab Quiz 11

64. Hubble discovered that galaxies are moving away from the Milky Way with velocities that are proportional to their
size.
color.
distance.
mass. 30

65. 3 times larger 6 times larger 9 times larger 3 times smaller
Consider two galaxies which are different distances from the Milky Way. One galaxy is 10 Mly distance and the other 30 Mly. How much larger or smaller is the recessional velocity of the more distant galaxy?
3 times larger
6 times larger
9 times larger
3 times smaller
6 times smaller
9 times smaller 30

66. Consider two galaxies that are the same size but one is twice as far away as the other. The more distant galaxy will have ____ compared to the closer galaxy.
½ the angular size
¼ the angular size
2 times the angular size
4 times the angular size 30

67. Newton’s Law of Gravity. the Doppler Effect.
In today’s lab you will determine the rotation rate of the planet Saturn by using
Hubble’s Law.
Newton’s Law of Gravity.
the Doppler Effect.
the luminosity-distance formula.
the distance modulus. 30

68. 1 parsec (pc) = 3.26 ly Absolute Magnitude C Apparent Magnitude B D A
4.2
1 parsec (pc) = 3.26 ly
Absolute Magnitude
5.0
6.0
0.0 B
3.3
2.0 D A
2.0
1.3
Sun
-26.5
5 pc
10 pc
15 pc

69. Verifying Kepler’s 2nd
Equal area in equal time. A2 A1
base

70. Verifying Kepler’s 1st P2 L3 P1 L1 L4 L2
Center
periluna

71. The AST105 Lab Exam is the week of November 29 (Week after Thanksgiving).
True
False 15