Download Early Astronomy

Science in Prehistory
Mankind has had a long
fascination with the ‘heavens’:
the motion of stars, Sun, Moon,
planets, comets, meteorites,
aurora, even observation of
supernovae.
Stonehenge
(Salisbury Plain, UK)
~2500BC
STONEHENGE (Salisbury Plain, UK)
built over ~17 centuries from~2800BC to 1100 BC. With the
biggest stones being laid about 2450BC.
Stone configuration correlated to winter and summer solstices.
Newgrange
(County Meath Ireland)
~3000BC
Newgrange: Passage Tomb
Central
Chamber
Illuminated
Around the
Winter
Solstice.
Stonehenge and
Newgrange: Conclusions
• An Awareness of the repeatable motions of
the Sun and Moon
• Despite popularised controversies,
Stonehenge is not regarded as the birthplace of
predictive astronomy.
• In comparison to their contemporary
Egyptian culture, we know very little of the
Neolithic and early Bronze Age peoples of
Northern Europe.
Egyptian’s Observation of the
Sun and Moon Motions.
• Monitoring seasonal variation for agriculture
Nile Flooded when sun rose near the star
Sirius (the “Dog star”, in the Canis Major
constellation; brightest star in the sky).
• Link lunar and solar ‘birth’ and ‘death’ to
religious festivals and an elaborate mythology.
Babylonian Era
• Monitored the movement
of the Sun, Moon and
Venus.
• Note special events:
eclipses and comets
• Prediction requires
mathematics and record
keeping! (necessitates a
long-lived, stable culture)
Numbers and Early Calendars
• Early Egyptians and Babylonians had 360
days in a solar year.
Origin of 360 in a circle.
•Egyptians divided the day into 24 hours.
•Babylonians developed a base 60 number
system.
Origin of 60 seconds and 60 minutes
•Egyptians introduced Leap years.
Formalised by Julius Caesar (46 BC)
Gregorian Calendar (1582 AD)
• Introduced by Pope Gregory XIII
• The precession of the equinoxes (due to
earth’s wobble on its axis) results in
seasons drifting over ~26,000 year cycle.
• Gregorian Calendar maintains the
seasons in the ‘proper’ months of the
year.
Gregorian Calendar
• 1 extra day in every 4 years (leap year) is
too much!
• Leap year at the close of the century
omitted, unless year a multiple of 400!
i.e : 1600, 2000 leap years
1700, 1800, 1900 not leap years
Aristotle (384-332 BC) and
Ptolemy (~150AD)
• In Greek period, there were a variety of
views on the nature of ‘reality’:
Earth, Fire, Air, Water
• Aristotle’s view spherical, stationary
Earth dominated.
• Developed to its full by Ptolemy in the
“Almagest” (Arabic for ‘the greatest’).
“7 Wanderers” = 7 Day Week
• “Wanderer” is the Greek meaning of
“planets”
• Wanderers in the Zodiac:
Sun, Moon, Mercury, Venus, Mars,
Saturn and Jupiter
(Latinised names)
Greek, Islamic and Chinese
Cultures Monitored the Heavens
• Greek Philosophers
formalised Geocentric
solar system
• Islamic Astronomers
developed new tools,
e.g. Astrolabe
• Chinese observed the
supernova of 1054 AD
Native Americans also Observed
the Motion of Key Stars
Big Horn
Medicine
Wheel,
Wyoming.
Spokes are
aligned to the
rising and
setting of the
Sun and
certain stars.