PRS Grading Policy

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PRS Grading Policy

• We will use the PRS almost every class for the
  rest of the semester, except for exams.
• You must send your response to each question
  before the time expires (typically 1-130
  minutes).
• A maximum 8 extra-credit points will be awarded
  each class 3 points will be given just for your
  participation (i.e., even if your answer is
  wrong).
• Your 3 lowest PRS scores will be dropped (i.e.,
  you have 3 free passes to use during the
  semester).
• Dont send answers for another person, which can
  zero your entire PRS credit.

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PRS RF Student Clicker/Remote
PRS rf
Two line display for indicating response and
status of received
Scroll Keys Send/Enter Backspace
Alpha, Numeric and T/F Keys
Setup Key Diagnostics include Battery Level
Uses Three (3) AAA batteries
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Setting Up Your Clicker
PRS rf

• Switch on your PRS unit (or clicker)
• Stop Scanning classes by pressing ? key
• Hit ? again to get to the Setup Menu
• Scroll up or down (? or ?) to ID
• Hit Send/Enter key (?)
• Type in your 8-digit Spire ID number
• Double-check it for correctness
• Hit Send/Enter (?)
• Hit ? then ? again to exit Setup Menu the unit
  will begin Scanning classes again

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Registering Your Clicker
PRS rf

• You must register your units RADIO ID on OWL to
  get credit for your answers!
• You dont have to be registered yet to receive
  credit for todays classdont forget to do it
  after class. (extra credit if by tomorrow!)
• To find your unit number, do the following
• Stop Scanning classes by pressing ? key
• Hit ? again to get to the Setup Menu
• Scroll up or down (? or ?) to Diagnostics
• Hit Send/Enter key (?)
• Your 6-digit/letter Radio ID is displayed

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Participating in a class
PRS rf

• Anytime after the class has started, switch on
  your unit and either let the unit scan for the
  class (this takes awhile) or type the letter or
  number associated with the class if you know it.
• Your units display will shut off to save battery
  powerhit any key to bring it back on (if you
  switch the unit off, you will have to rejoin)
• You send an answer by hitting the ? key while a
  question is running.
• Make sure you get the Received
  message.

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PRS ID

• What is your 8-digit university ID?
• (Type in your ID number as your answer to this
  question then press ?. This is a black
  questionfailure to answer it correctly may lead
  to zero credit.)

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PRS The Night Sky

• Which of the following is a correct statement
  about stars?
• They hardly move over a night.
• Stars rise and set just like the Sun.
• All stars set in the morning.
• We see the same stars over a year.

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The Night Sky
Night is a curious child, wanderingBetween earth
and sky, creepingIn windows and doors,
daubingThe entire neighborhoodWith purple
paint. - Frank Marshall Davis
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So MANY objects.How Do We Make Sense of it ALL??
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Goal

• To begin a discussion on how we locate objects in
  the night sky.
• Understand the concept of angular size and
  separation, projection, and celestial sphere and
  coordinates.
• To understand the daily and annual motions of the
  Sun and stars.

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Angular size, separation, and projection
The Sun is physically 400 times larger than the
Moon. Why is their angular size is the same?
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Angle diameter (in radians) diameter/distance Fu
ll circle 2? (in radians)360
degrees360o 1o60 arcminutes 60 1 60
arcseconds 60
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Angular Size
Some Examples Horizon to zenith (point
overhead) 90o Your fist
at arm's length 10o Your
fingernail at arm's length 1o
60' Sun or Moon seen from Earth 0.5o 30'
Smallest detail visible to naked eye
1' 60'' Smallest detail visible by a
single telescope from Earth's surface 1''
Betelgeuse (largest star) seen from Earth
0.004'' So all the stars we see, except for the
Sun, are point-like! The distance between them is
the angular separation.
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Constellations
88 official constellations divide the sky into
areas with clearly boundaries. The names of
constellations are in Latin. But most bright star
names derived from ancient Arabic. The original
constellations were invented by farmers over 5000
years ago. Remember that the constellations are
not real!
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Projection
Big Dipper ---- an asterism
(Unofficial groupings of stars)
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The North Star

• Stand up
• Looking up, without turning your head, slowly
  rotate (so the ceiling turns counterclockwise)
• The lights in the room (or the holes in the
  tiles) are like stars on the celestial sphere.
• Notice that one light or tile directly overhead
  doesnt particularly move.

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How long to go all the way around?
1 day
b. 1 week
c. 1 month
d. 1 year
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How long to go all the way around?
1 day
b. 1 week
c. 1 month
d. 1 year
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Are there stars in the sky during the daytime?
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Starry Night Pro Planetarium
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Location, location, and location
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Longitude and Latitude

• We define our north-south position on Earth by
  our distance from the equator
• the north pole is at 90 deg north
• the south pole is at 90 deg south
• We define our east-west position by our angle
  relative to an arbitrary point in Greenwich
  England.

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Zero Longitude
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Lost at Sea?

• Polaris is just about as high above the horizon
  as your lattitude.
• The location of constellations at certain time
  can be used to tell the longitude.

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Celestial Coordinates

• Positions on the Celestial Sphere are analogous
  to Longitude and Latitude.
• A stars longitude is called its Right
  Ascension
• A stars latitude is called its Declination.
• Celestial poles like the poles on earth, extended
  into sky.
• So is the celestial equator.

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There are two ways to think about the motion of
the sky - the C.S. rotates - or the
Earthrotates while the sky sits still.
Sometimes one works better thanthe other
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What part of the sky can you see?
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Questions

• Where on Earth would stars circle straight
  overhead around NCP?
• Where on Earth can you see both poles?

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In what direction is the observer facing?

• toward the South
• toward the North
• toward the East
• toward the West

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Imagine that from your current location you
observe a star rising directly in the east. When
this star reaches its highest position above the
horizon, where will it be?

• high in the northern sky
• high in the southern sky
• high in the western sky
• directly overhead

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Where would the observer look to see the star
indicated by the arrow?

• High in the Northeast
• High in the Southeast
• High in the Northwest
• High in the Southwest

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Nightly Motion of the Stars

• Imagine looking toward the East as a star rises
  above your horizon - what does it do after that?

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Time Zones

• 24 time zones, designed such that local noon
  roughly corresponds to the time when the sun is
  highest in the sky
• If it is noon on the Prime Meridian in Greenwich,
  UK, it is midnight on the opposite side of the
  world. This midnight line is called the
  International Date Line

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Universal Time

• The time for many astronomical events is given in
  Universal Time (UT), which is (approximately) the
  local time for Greenwich, England --- the
  Greenwich Mean Time or GMT.