class website up and running @ not d2l !!...
TRANSCRIPT
ANNOUNCEMENTS• CLASS WEBSITE UP AND RUNNING @
http://casaweb.colorado.edu/astr2000/
OPTIONAL OBSERVING SESSION TONIGHT AT SOMMERS-BAUSCH
OBSERVATORY (SBO) AT 8:30pm (weather permitting!). I will send
email by 8:00pm at latest IF ON/OFF.
OFFICE HOURS:
STOCKE: WED 1:30—2:30 PM AT PEKOE’S COFFEE SHOP IN THE
ATLAS BUILDING or BY APPOINTMENT
WALLACE AND VANN: HOMEWORK CLUB WED 11AM-1PM & 4-6
PM IN DUANE ROOM D142 or BY APPOINTMENT.
OPTIONAL DARK SKY OBSERVING TRIP: OCT 6th (“RAIN DATE”
OCT 7th ) TO THE CU MOUNTAIN RESEARCH STATION
ANY STILL ON WAIT LIST CONTINUE COMING TO CLASS. 1 STILL
ON WAIT LIST AT THIS TIME
Not D2L !!
Up for Discussion Today
1. DIURNAL (DAILY) MOTION OF THE SKY
2. COSMIC WHIRLPOOL AND THE 6 DIRECTIONS
CIRCUM-POLAR STARS
3. ALIGNING THE PYRAMIDS
4. MOTIONS OF SKY AT DIFFERENT LATITUDES
5. THE MERIDIAN, CELESTIAL EQUATOR, AZIMUTHS,
ALTITUDES, THE POLYNESIAN “STAR COMPASS”
6. INTRODUCTION TO A FEW CONSTELLATIONS
QUESTION
HOW DO THE STARS APPEAR TO MOVE ACROSS THE SKY
EACH NIGHT ?
1. EAST TO WEST JUST LIKE THE SUN OR MOON
2. ALL MOVE DIFFERENT DIRECTIONS DEPENDING ON
THEIR LOCATION IN THE SKY
3. ALL MOVE DIFFERENT SPEEDS DEPENDING ON THEIR
DISTANCE FROM US
4. THE STARS STAY AT FIXED LOCATIONS ALL NIGHT LONG
ANCIENT PEOPLES DID NOT TAKE THE MOTIONS THEY SAW
IN THE HEAVENS AS EVIDENCE THAT THE EARTH MOVES. If you could see stars in the daytime, this is what the sky would look like facing
south at noon on a specific day in the summer.
Ancients would say “the Sun is in the zodiac constellation of Gemini”. In what
constellation would the Sun be at sunset that same day?
Leo, Cancer, Gemini, Taurus, Aries, or Pisces?
,
DAILY MOTION OF THE SKY.: GREEN LINE IS THE CELESTIAL EQUATOR
WHEREON STARS RISE DUE EAST AND SET DUE WEST
THE CELESTIAL SPHERETHE CELESTIAL SPHERE
What constellations would be visible in the sky after Sunset this day ?
If you could see stars in the daytime, this is what the sky would look like facing
south at noon on a specific day in the summer.
Ancients would say “the Sun is in the zodiac constellation of Gemini”. In what
constellation would the Sun be at sunset that same day?
Leo, Cancer, Gemini, Taurus, Aries, or Pisces?
,
What constellations would be visible in the sky before Sunrise this day ?
If you could see stars in the daytime, this is what the sky would look like facing
south at noon on a specific day in the summer.
Ancients would say “the Sun is in the zodiac constellation of Gemini”. In what
constellation would the Sun be at sunset that same day?
Leo, Cancer, Gemini, Taurus, Aries, or Pisces?
,
DAILY MOTION OF THE SKY. GREEN LINE IS THE CELESTIAL EQUATOR
ON WHICH STARS RISE DUE EAST AND SET DUE WEST
ALTITUDE (OR ELEVATION) IS THE ANGLE UP FROM THE
HORIZON.. Varies between 0 and 90 degrees.
AZIMUTH (OR BEARING) IS THE ANGLE ALONG THE HORIZON
FROM NORTH THRU EAST .. Varies between 0 and 360 degrees.
THE RISING AND
SETTING POINTS OF
ALL STARS IS
SYMMETRICAL
AROUND THE
MERIDIAN (NOT 180O
OPPOSITE).
THIS IS ALSO TRUE
FOR THE SUN, MOON
AND PLANETS ON ANY
GIVEN SINGLE DAY
THESE RISING AND
SETTING AZIMUTHS
ARE FIXED AT ANY
SPECIFIC LATITUDE
To make sure you “get” this:IF Mao Piailug sailed towards the rising point
of Vega to get from his home island to a nearby island … to get back home he sails:
1. Towards the setting point of Vega
2. Towards the rising point of Antares
3. Towards the North Star
4. Towards the Southern Cross
5. Towards the setting point of Antares
6. Away from the rising point of Vega
7. Away from the rising point of Antares
DAILY MOTION OF THE SKY. GREEN LINE IS THE CELESTIAL EQUATOR
WHEREON STARS RISE DUE EAST AND SET DUE WEST
SOME STARS NEVER RISE OR SET: THESE ARE CALLED
“CIRCUM-POLAR STARS”
HOW ANCIENT PEOPLE ALIGNED THEIR
STRUCTURES AND SO CAME INTO
ORIENTATION WITH THE COSMOS ?
THEY USED
THE “COSMIC
WHIRLPOOL”.
FOR ANCIENT HUMANS THE MOTIONS
VISIBLE IN THE SKY DEFINED THE VERY
NATURE OF TIME AND INCREMENTS OF TIME
DURING THE DAY: THE MOTION OF THE SUN AND ITS
SHADOW DEFINED THE “HOURS OF THE DAY”. NOON IS
THE TIME THAT THE SUN CROSSES THE MERIDIAN
THE DAY IS THE TIME BETWEEN SUCCESSIVE NOONS
AT NIGHT THERE WERE THE DECANS. STAR GROUPS
THAT DEFINE THE NIGHTTIME HOURS BY THEIR
SUCCESSIVE RISINGS, ONE AFTER ANOTHER.
. THE TRADITION OF THE 24 HOUR DAY PROBABLY
CAME FROM ANCIENT EGYPT BUT NO ONE KNOWS FOR
SURE.
OF THE 30 REMAINING EGYPTIAN OBELISKS: 7 ARE IN
EGYPT AND ELEVEN ARE IN ROME !!!
OBELISKS ARE GIANT SUNDIALS !
EAST-TO-WEST
MOTION OF STARS
CAN BE USED TO
TELL TIME AT NIGHT:
THE EGYPTIAN
“DECANS”
One decan
“constellation” is
marked in a green box
and “marches” across
the 70 day calendar
diagonally as it rises
earlier and earlier
each 10 days.
NOTE: Big Dipper (“Bull’s
Thigh” constellation at top
!)
Any one night has 12 “hours”
EAST-TO-WEST
MOTION OF STARS
CAN BE USED TO
TELL TIME AT NIGHT:
THE EGYPTIAN
“DECANS”
One decan
“constellation” is
marked in a green box
and “marches” across
the 70 day calendar
diagonally as it rises
earlier and earlier
each 10 days.
NOTE: Big Dipper (“Bull’s
Thigh” constellation at top
!)
FORGOT TO SAY: THIS CALENDAR IS ON
INSIDE OF AN OLD KINGDOM SARCOPHAGUS
DAILY MOTION OF THE SKY. GREEN LINE IS THE CELESTIAL EQUATOR
WHEREON STARS RISE DUE EAST AND SET DUE WEST (slides)
HORIZON TO
ZENITH = 90 O
(CALLED
ALTITUDE)
FULL
CIRCUMFERENCE
OF HORIZON =
360O
(CALLED
AZIMUTH)
BASE 60 COMES
FROM
BABYLONIANS
UNITS OF TIME CREATED UNITS OF ANGLES
IN THE SKY:
Circa 2000 BCE Babylonians had a calendar
of 360 days with 12 lunar months of 30 days.
So they divided the circular path of the Sun
and Moon through the sky into 360 degrees,
one day for each day of the year
The Sun moves ~ 1 degree each day through
the stars.
Because the Babylonians used a “base 60”
numbering system (we use a “base 10”
system), these degrees were divided into 60
parts and those parts into 60 parts.
1 degree = 60 arc-minutes &
1 arc-minute = 60 arc-seconds
1 arcminute ≈ resolution of human eye
1 arcsecond ≈ resolution of a ground-based
telescope
Prague Orloj
1410 CE
Prague
Czechoslovakia
City Hall