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History of Astronomy Evening Classes Week Four Presented by Oisín Creaner.
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Transcript of History of Astronomy Evening Classes Week Four Presented by Oisín Creaner.
History of Astronomy
Evening Classes
Week Four
Presented by Oisín Creaner
The History of Astronomy 3200 BC to Present.
1.Prehistorical Astronomy
2.Greek and Arab Astronomy
1.Renaissance to Instruments
1.Modern Astrophysics
Newgrange
Passage Tomb, Co Meath
Built 3200BC
Light Box AlignedOn WinterSolstice
Newgrange Image Jimmy Harris
(1)Greeks were great theorists,but poor observers or experimenters.
(2)Greeks used Babylonian records & Greek geometry.
(3)Ionians (c 600 BC) - first Greekcosmology. Impersonal laws replacemythology.
GREEK ASTRONOMY (650 BC - 150 AD).
Pythagoras
Aristarchus (310 -230 BC) - How to measure therelative distances between the Earth, Sun and Moon
(4)Pythagoreans (c 600 BC) - saw numbers as the basis ofreality + wrote of a spherical earth.
GREEK ASTRONOMY (650 BC - 150 AD).
Aristotle & Plato
(5)Aristotle (fl 350 BC)-Round earth at thecentre of the cosmos.
Aristotle's cosmology isrooted in common sense& rationality.
Aristotle’s Cosmology
•Earth is at Rest
•Earth is Round
•Earth is the Centre of the cosmos
(6) Celestial Sphere's motions arepredictable, what about the 7 planets?
Plato (fl 400 BC) challengedgeometricians to describeplanetary motion in lawful terms.
This became Astronomy's project fornext 2000 years.
GREEK ASTRONOMY (650 BC - 150 AD).
(7) The most elaborateGreek astronomer.
The "Almagest“ (c 145 AD)gave mathematical modelof planet's motions thatcould be calculated for anydate, past or future.
Ptolemy ofAlexandria
Arab Medieval Astronomy
Early formal catalogues•Names of brigtest stars
Refined Greek Models•Doubts about Ptolemy
Advanced Mathematics•Calculated movement
Arab Medieval Astronomy
History of Astronomy
Evening Classes
Week Four
Presented by Oisín Creaner
Nicholas Copernicus
Tycho Brahe(14 December 1546 – 24 October 1601)
Johannes Kepler
Galileo Galilei
Isaac Newton(1642-1727)
When white light is passed through a prismit is split up into its component colours.
William Herschel
Otto Struve
Used parallaxmeasurements todetermine distanceto nearby stars.
Robert Bunsen (1811 - 1899)Gustav Kirchoff (1824 - 1887)
1859 - Elementsare identified insunlight
The Spectroscope
Frauenhofer Lines
Angelo Secchi’sStellar Spectra Classification
Sirius Type Stars
Sun-like stars
Red-Giant Variables
Red-dwarfs
Christian Doppler
Crab Nebula (M1) Original SN1054Lord Rosse Observed 1848
Messier Catalogue
Long observation
John Herschel(1792-1870)
Pioneer ofAstrophotography
Herman von Helmholtz
Suggested thatgravitational contraction
was the source of theSun’s energy.
Edwin Hubble
“The spiral nebulaeare receeding atspeeds proportionalto their distances”
Hans Bethe
Worked out thatsunlight comesfrom hydrogenfusion (1939).
Post WW 2
The observablespectrum is broadened
Thank You
www.astronomy.ie/handoutswww.stellarium.org
Useful websites
