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Unformatted text preview: Chapter Two
Chapter Questions for the Day
Questions What is a Constellation? What is Archeoastronomy? What are the motions of the sky? What is a Constellation?
What Constellations are apparent star patterns in the
Constellation patterns were based in mythology,
so each culture had their own set of
Constellation patterns are consistent set (88 in
all) throughout the world.
Constellations are different from star clusters
which are gravitationally bound set of stars.
which Constellation Simulator
Constellation http://www.astro.wisc.edu/~dolan/constellations/java/Orion.html Constellation Mythology
Constellation http://www.comfychair.org/~cmbell/myth/myth.html What is Archeoastronomy?
Archeoastronomy is the science of relating
astronomical processes in the sky with
objects located in archeological sites.
objects Objects on the site need to line up with
astronomical events (equinoxes, solstices,
eclipses, rising, and setting).
eclipses, These archeological sites were usually
used by astrologers, priests, tribal leaders. Stonehenge
Stonehenge http://www.amherst.edu/~ermace/sth/photos.html Stonehenge – Before and After
2950-2900 BCE Phase III
2550-1600 BCE http://witcombe.sbc.edu/earthmysteries/EMStonehenge.html What are the Motions of the Sky?
What Motions of Stars Motion of the Sun Motions of the Moon Motions of the Planets Angular Distances
Angular Degrees, Minutes, Seconds 1° = 60’
1’ = 60” Hours, Minutes, Seconds 1 hour = 60 min = 15°
1 min = 60 sec Your hand equals 10 degrees in the sky. Angular Motion
Angular The moon takes 27 days to go around in
The its orbit. What is its relative motion to the
stars in days? In hours?
v=d/t v=360°/27 days
v=13.33 °/days (1 day/ 24 hr)
v=0.56 °/hour Motions of Stars
Motions Diurnal Annual Due to the Earth orbiting the Sun. Procession Due to the rotation of the Earth. Due to the wobble of the Earth on its axis.
Due All motions are represented in the SC001 chart. Diurnal Motion http://www.mhhe.com/physsci/astronomy/arny/instructor/ch01imagebank.html Annual Motion
Annual Motion of the Sun
Motion The Sun travels along the ecliptic. Due to the tilt of the Earth (23.5)
The Sun rises and sets at different positions
The Sun’s annual motion is slightly faster
than the rest of the stars.
than The Sun moves 2 hours in Right
Ascension each month, which is called
Sidereal Motion of the Moon
The Moon has its own path around the sky
due to a tilt of its revolutionary axis.
due The Moon has phases due to amount of
sun light reflecting off the moon.
sun The Moon’s synodic period (phase time) is
longer (29.5 days) than its sidereal period
(time of orbit, 27 days)
(time Eclipses occur when a line of nodes occur. Phases of the Moon
Phases http://www.astro.wisc.edu/~dolan/java/MoonPhase.html Line of Nodes
Line http://www.ccs.neu.edu/home/sblanco/astro/moon.html Motions of the Planets.
Motions The planets travel around the ecliptic. The
The planets seem to go backwards in
comparison the stars in some parts of their
orbit because the Earth passes the planet
in its orbit. This is known as retrograde
motion. The planet’s name means “wanderer” in
both Planet’s Path
Planet’s Retrograde Motion
Retrograde Homework 2
Homework Look up on the web (at google.com or ask.com)
to find information on an Archeoastronomy ( but
not Stonehenge) site. Then write a paragraph
summary about this site, please cite the website
The Earth takes 365.25 days to go around the
Sun. What is its relative speed to the stars in
days? In hours? (Hint: Use the example in this
Page 34, CQ 4,10 ...
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