The Ancient Mystery of the Planets The Ancient Roots of Science

5 planets are visible by eye from Earth “Planet” is from the Greek word for “wanderer” The planets generally drift from west to east relative to the stars

BUT sometimes they appear to do something strange… “retrograde motion” “prograde motion” Retrograde motion is only apparent

What’s really happening

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Why did the ancient Greeks reject the heliocentric model? “Parallax” is much to small to measure without modern telescopes

The Ancient Roots of Science DengFeng, China Stonehenge, United Kingdom Chichen Itza, Mexico

Practical uses of astronomy To ancient people, the sky was both a clock and a calendar The orientation of the waxing crescent moon could be used to predict the rainy season in central Nigeria

The days of our week were originally named for the “wanderers”

Time can be told during the day using the Sun’s position

Vrihat Samrat Yantra, a Jantar Mantar in Jaipur, India The world’s largest sundial, marked in increments of 2 seconds!

At night the Egyptians used a “star clock” It told where various stars could be seen at different times of night throughout the year.

Many cultures built structures to mark specific astronomical occasions Stonehenge

Stonehenge, built in stages over 1200 years, has alignments with many astronomical events. It was also used as a burial place for the elite This lane is now known to have been a naturally occurring stone path or lane

Sun Stonehenge Location: W 1°49'34.0", N51°10'44.0", 100m Date Begin Rise Az. Transit Alt. Set Az. End (UT1) Astron. Astron. Twilight Twilight h m h m ° h m ° h m ° h m 2015 Dec 10 (Thu) 05:57 08: :00 16S 16: : Dec 11 (Fri) 05:58 08: :00 16S 16: : Dec 12 (Sat) 05:59 08: :01 16S 16: : Dec 13 (Sun) 06:00 08: :01 16S 16: : Dec 14 (Mon) 06:01 08: :02 16S 16: : Dec 15 (Tue) 06:02 08: :02 16S 16: : Dec 16 (Wed) 06:02 08: :03 16S 16: : Dec 17 (Thu) 06:03 08: :03 16S 16: : Dec 18 (Fri) 06:04 08: :04 15S 16: : Dec 19 (Sat) 06:04 08: :04 15S 16: : Dec 20 (Sun) 06:05 08: :05 15S 16: : Dec 21 (Mon) 06:05 08: :05 15S 16: : Dec 22 (Tue) 06:06 08: :06 15S 16: : Dec 23 (Wed) 06:06 08: :06 15S 16: : Dec 24 (Thu) 06:07 08: :07 15S 16: : Dec 25 (Fri) 06:07 08: :07 15S 16: : Dec 26 (Sat) 06:08 08: :08 16S 16: : Dec 27 (Sun) 06:08 08: :08 16S 16: : Dec 28 (Mon) 06:08 08: :09 16S 16: : Dec 29 (Tue) 06:08 08: :09 16S 16: : Dec 30 (Wed) 06:09 08: :10 16S 16: : Dec 31 (Thu) 06:09 08: :10 16S 16: :12 When people say “The Sun shines through this opening only on the morning of the solstice”, they’re being less than informed.

Callenish, Isle of Lewis, Scotland Newgrange, Ireland

Chichen Itza, Yucatán, Mexico El Caracol – alignments with the rising and setting of Venus El Castillo – same number of steps as days in a year Alignments with the equinoxes

Great Kiva in Chaco Canyon The Sun Dagger in Chaco Canyon

Chinese astronomers have been recording astronomical observations for at least 5000 years Machu Picchu includes alignments with summer and winter solstice sunrises Micronesia – stars for navigation

Do the structures built by ancient peoples for observing celestial events prove that they were doing science? A.No. There was no “science” before Isaac Newton. B.Yes. Observing the stars is scientific. C.No. Observation is only the first step in the scientific process. D.Yes. Since they were able to detect the solstices, they were doing science.

Astro-Cash Cab! Jeffrey Crawford Nick Kirpes Curran Grant Tyler Zito LeKisha Sanchez

1) How much parallax does the closest star (other than our Sun!) display? less than one arcsecond about 20 arcseconds around 1 arcminute The closest star does not show parallax, as far as modern instruments can detect

2) In which direction is the “normal” motion of the planets relative to the stars? East-to-west West-to-east They don’t actually move

3) True or False? The biggest drawback to a sundial is it’s poor accuracy.

4) True or False? Before the invention of mechanical clocks, it was not possible to tell the time at night