Astronomy = Astrometry? History of Old Astronomy ( )

Transcription

1 Astronomy = Astrometry? History of Old Astronomy ( )

2 note Astrometry means measuring the position of a celestial object in a sky. Without telescopes, this is what ancient astronomers can do for their best. The periodic motion of the Sun and the Moon against the star background helped ancient people establish calendars and astrology. Therefore astrometry has had an strong impact on our daily life. Astrometry is the essence of the ancient astronomy. In the modern astronomy, astronomers have more tools and techniques to study celestial objects. Astrometry then becomes only one of subdisciplines of the modern astronomy. In the last few slides of this lecture, you will find much more precise astrometry achieved by modern telescopes. This old but updated technique would even help us find a earth-mass planet outside of the Solar System in the future. Basically astrometry only gives a 2-D map of the sky. Nevertheless, Tycho adopted the idea of parallax to argue about the distance (i.e. the 3rd dimension) of celestial objects. We will learn more about this in one of the next lectures. 2006/10/11 2

3 (S (Stars) (the Sun) (too far!) (Polaris for now) ( ) 88 (constellation) ( ) ( ) 13 ( 12) ( ) ( ) 2006/10/11 3

4 From the view of the earth (ecliptic) Summer (winter) in Northern (southern) hemisphere winter (summer) in northern (southern) hemisphere 2006/10/11 4

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9 ( ) 1316 The Secret Language of The Stars and Planets by G. Cornelius & P. Devereux (sundial) /10/11 9

10 The fact is ( ) ( ) ( ) ( )btw, do you still remember what causes a month? one year = days ( ) () () 2006/10/11 10

11 6pm ( ) 6am 12pm sunlight In summer (winter), day Is longer (shorter) than night. But 2006/10/11 11

12 Summer Solstices in the northern hemisphere to Polaris sunlight equator 23.5 ( ) spin axis night day ( ) 2006/10/11 12

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14 winter triangle summer triangle : 2006/10/11 14

15 Polar Regions (Polaris) = equator East or West 2006/10/11 15

16 13?! ( is not included in astrology 2006/10/11 16

17 Mismatch by one sign due to Precession Sign Aries(Ram) Taurus(Bull) Gemini(Twins) Cancer(Crab) Leo(Lion) Virgo(Virgin) Libra(balance) Scorpio(Scorpion) Ophiuchus Sagittarius(Archer) Capricorn(Goat) Aquarius(Water Bearer) Pisces(Fishes) Astrology Mar 21 - Apr 19 Apr 20 - May 20 May 21 - Jun 20 Jun 21 - Jul 22 Jul 23 - Aug 22 Aug 23 - Sep 22 Sep 23 - Oct 22 Oct 23 - Nov 21 - Nov 22 - Dec 21 Dec 22 - Jan 19 Jan 20 - Feb 18 Feb 19 - Mar 20 Actual Apr 20 - May 13 May 13 - Jun 21 Jun 21 - Jul 20 Jul 20 - Aug 11 Aug 11 - Sep 18 Sep 18 - Nov 1 Nov 1 - Nov 22 Nov 22 - Dec 1 Dec 1 - Dec 19 Dec 19 - Jan 19 Jan 19 - Feb 18 Feb 18 - Mar 13 Mar 13 - Apr /10/11 17

18 Ophiuchus () The ecliptic passes only small part of Ophiuchus Note that the ecliptic does not align with the Milky Way. 2006/10/11 18

19 Astrology & Astronomy Ancient times: astrology was based on astronomy Nowadays: conflicts between astrology & astronomy example I: Astrologers ignore the 13th sign of horoscope and precession. example II: Marina Bai (born 1965), a Russian astrologer, sued NASA in July, 2005 for US$ million. She claimed that the NASA probe that crashed into the Tempel 1 comet will interfere with her astrology work because the comet would no longer be the same, claiming it "ruins the natural balance of forces in the universe". remark: alchemy chemistry astrology astronomy 2006/10/11 19

20 ( ) For details: 2006/10/11 20

21 The Secret Language of The Stars and Planets by G. Cornelius & P. Devereux Stonehenge (England) 2006/10/11 21

22 Stonehenge (England) align 5000 years ago?( ) Metonic Cycle: 18.6 years (moon s nodal period) The Secret Language of The Stars and Planets by G. Cornelius & P. Devereux 2006/10/11 22

23 (precession) /10/11 23

24 The Great Pyramid (Egypt, 2600BC) The Secret Language of The Stars and Planets by G. Cornelius & P. Devereux Orion symbolizes Osiris 2006/10/11 24

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26 Direct & Retrograde( ) ) Motion ( ) planet (Greek) means wanderer ( ) 2006/10/11 26

27 A.D. 125? Ptolemy s geocentric model Planets ( ) wander among stars ( ) For more info: ( ) 2006/10/11 27

28 Explanation of Planetary Motion fast slow 2006/10/11 28

29 Astronomers (A.D ) Copernicus ( ) Heliocentric theory Galileo ( ) First use a telescope to watch the sky Tycho ( ) Half helio + Half geo & Kepler ( ) 3 laws Newton ( ) Law of universal gravitation 2006/10/11 29

30 Parallax ( ) 2006/10/11 30

31 Parallax of a Nearby Object in Space measure distance: Modern astronomers use parallax to estimate the distance of nearby stars. 2006/10/11 31

32 Tycho s cosmology Tycho used parallax argument against heliocentric concept. Science is based upon proofs. Sometimes many models can exist because the experiments/observations are not precise enough to distinguish models /10/11 32

33 Barnard s s Star (1916) 2 nd closest star system (1 st is alpha Centauri) angle: 1 circle= per year Wikipedia.org: 0.17 solar masses 5.96 light years away 2006/10/11 33

34 Hipparcos Satellite (space astrometry) Pleiades ( Subaru, distance=400 light years) animation generated using Hipparcos data. This is an 8x6 degree field. The movement of the stars over 120,000 years is shown. 2006/10/11 34

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36 Summary 2006/10/11 36