Moon Project

1
Moon Project

• Tonight is CLEAR. Do project!!!
• Locate the Moon with respect to the STARS on the
  star map (NOT the horizon)
• You need to find star patterns you recognize in
  the sky and on the map to determine where the
  Moon is
• Depending on the time of night you look the Moon
  will be in different parts of the sky, but on a
  single night always close to the same stars.

2
Announcements

• 30 students have still not registered and joined
  our class on Astronomy Place.
• The assignment for Monday is a review with
  questions taken from past ISP205 exams. It will
  be posted on Angel by Thursday evening. It is
  good practice for the quiz and mid-term exam.
• Assignments on Angel and Astronomy Place can be
  done over until you get a perfect score. These
  are easy points.Assignments, Activities
  Quizzes 25 of grade.

3
More Announcements

• Quiz and Review - Monday Feb 9
• 1st Mid-Term Exam - Wednesday Feb 11Will cover
  chapters 1-6 (sections 6.1-3 only)

4
Objectives Light(from syllabus)

• Describe the Structure of an atom
• Describe how energy is stored in atoms
• Describe the relation between temperature and
  motion
• Describe the ways in which light acts as a wave
  and as particles
• Describe the different types of light in the
  electromagnetic spectrum and the relation between
  type of light, wavelength, energy and temperature
  of the source of the light.

5
What is a FACT what is a THEORY?

• Write your name and student ID on your index card
  and write your own statement of what is a FACT
  and a THEORY, with one example of each.
• Then we will discuss your ideas.

6
Why is Light important?

• We cant touch, hear or smell the stars. ALL
  of our INFORMATION about the rest of the universe
  (except for some samples returned from the Moon)
  comes to us via LIGHT.

7
Big Picture

• Light carries information about the atoms that
  produced it. We need to understand the
  interaction between Light and Atoms.
• There is more to light than meets the eye. The
  visible light that our eyes can see is only a
  small portion of the complete electromagnetic
  spectrum.
• The properties of light, especially the amount of
  light of different energies - its spectrum -
  gives us information about distant objects.
  Different portions of the spectrum contain
  different pieces of the story of a distant object.

8
How Do We See?
Light
Eye
Pencil
9
How Do We See?
Light
Eye
Pencil
10
How do we see?

• An object must give off light and our eye must
  receive the light in order to see the object.
• That light might be emitted by the object (e.g. a
  light bulb or the Sun)
• Light from another source can be reflected off
  the object (e. g. a pen reflecting light from a
  bulb or the Moon reflecting sunlight)
• If there is no light, cant see the object.

11
Light is an Electromagnetic WAVE

• A wave is a moving pattern
• Light is a changing pattern in the electric and
  magnetic force (e.g. shaking a rope)
• Properties of waves
• Wavelength (?) distance between waves
• Period (P) time between waves
• Frequency (f) number of waves per unit
  time(analogy busses on Grand River Ave.)
• Waves transport energy

12
Light as a Wave

• For light ? cP
• c speed of light
• P 1/ f
• The higher f is, the smaller ? is, and vice
  versa.
• Our eyes recognizef (or ?) as color!

13
Light is a stream of PHOTONS

• A particle is a thing
• Light is also a stream of particles called
  PHOTONS
• Properties of photons
• Frequency (f)
• Energy, e hf hc/ ? (hnumber called Plancks
  constant)
• Higher frequency shorter wavelength higher
  energy

14
Spectrum of Light

• Visible light is only a small part of the
  electromagnetic spectrum
• Lowest enegy light is radio
• Highest energy light is gamma rays

15
Visible Light
16
Spectrum of Light
X-rays lt 20 nanom High energy, short ?
Ultraviolet 20 nm - 0.4 microm
Visible blue green yellow orange red Wavelength 0.4 -0.7 micrometers
Infrared 1 microm - 1 mm
Microwave 1 mm - 1 cm
Radio gt 1 cm Low energy, long ?
17
Matter is made of ATOMS

• Atom is nucleus orbited by electrons
• Nucleus - composed of protons ( charge)
  neutrons (0 charge)
• Electrons (- charge) orbit nucleus attracted by
  electric force
• Electric Force
• Produced by charge
• Opposite charges attract, like charges repel
• Decreases with increasing distance
• Element is determined by number of protons in
  nucleus

18
Atoms

• Crude Model Atom solar system
• If person proton or neutronelectron cotton
  candy orbiting 100 km (60 mi) away (Flint)
• If nucleus raisin, electron 400 m away, next
  atom is 2.5 - 25 mi away
• If Sun 3 ft diameter ball, Earth raisin 100 m
  away, nearest star distance to Sun

19
Atom
electron
nucleus
p
e-
n
proton
neutron
20
Hydrogen
e-
p
atomic number 1
atomic mass number 1
21
Hydrogen
Deuterium
e-
isotope
p
n
atomic number 1
atomic mass number 2
22
Helium
e-
p
p
n
n
e-
atomic number 2
atomic mass number 4
23
Atoms

• Neutral Atom - number of electrons number of
  protons
• Usual state at LOW temperatures
• Ion - some or all of electrons have been knocked
  out of atom
• Usual state at HIGH temperatures

24
What if an electron is missing?
ion
e-
p
p
n
n
atomic number 2
He1
atomic mass number 4
25
Temperature

• Measures motion of atoms ( molecules, ions,
  nuclei, electrons)
• Hotter moving Faster
• kT 1/2 m v2

knumber
mmass
Ttemperature
vspeed
Not a required equation
26
Temperature Scales
27
Emission Absorption of Light
Photons are emitted or Absorbed when an electron
changes its Energy
28
Assignment for Monday

• Monday - QUIZ Chapters 1-6.3 Review
• Assignment for Monday - Sky Assignment 7,review
  questions on Angel (posted Thursday)
• Problems with Astronomy Place or Angel - clear
  browser cache cookies and try again
  (instructions linked to course web page and on
  Angel)