Galileo Galilei 1564-1642

1. From Spyglasses to Space TelescopesorA Saga That Began With Galileo Galileo Galilei 1564-1642

2. Galileo was……. • An inventor • Father of Experimental Physics • Father of Modern Astronomy

3. Born: 15 Feb 1564 Pisa Professor of Mathematics University of Padua 1592-1610 1610: Chief Mathematician to Grand Duke of Tuscany Cosimo II de Medici

4. Development of Telescopeis linked to that of spectacles With age, the eye progressively loses its power to accommodate, that is to change its focus from faraway objects to nearby ones. This condition, becomes noticeable for most people in their forties, when they can no longer focus on letters/ books held at a comfortable distance from the eye. Magnifying glasses became common in the thirteenth century for reading

5. Lipperhey (or Lippershey!) was a spectacle maker in Holland. One story behind the creation of the telescope states that two children were playing with lenses in his shop. The children discovered that images were clearer when seen through two lenses, one in front of the other. Lipperhey was inspired by this and created a device very similar to today's telescope. Lipperhey (or Lippershey!)

6. In 1608, Lipperhey found that while viewing a distant object through combination of a convex and a concave lens, the object appeared closer and magnified. For this purpose, however, the two lenses had to be placed at just the right distance from each other.

7. Lipperhey never used his telescope to look at the stars. He believed that his new invention would mainly benefit seafarers and soldiers - and for spying purposes. This is how the telescope was born - in the garb of a spyglass!

8. Significance of Galileo The actual term "telescope" was coined on April 14, 1611 by Prince Frederick Cesi at a reception where Galileo was demonstrating one of his instruments. He did not just ‘use’ the telescope - he fabricated his own … He did not just ‘see’ the heavens, but applied scientific method to interpret what he saw…

9. Galileo’s telescope • He realized that the magnification was proportional to the ratio of the power of the concave (eyepiece) lens to the convex (more distant) lens. • In other words he needed a weak convex lens and a strong concave lens. • Opticians only made glasses in a narrow range of strengths, and three or so was the best magnification available with off the shelf lenses. Galileo found out about this invention in the early 1609 and immediately set about improving it.

10. Galileo learned to grind his own lenses, and by August 1609, he had achieved about eight-fold linear magnification. He demonstrated his new invention to a gathering of officials on August 1609.

11. Galilean Telescope Galileo used a long focal length objective and a short focal length eye piece. If the focal length of the objective is Fo and the focal length of the eyelens is -Fe, the distance between them must be Fo - Fe, and the power (angular magnification) is Fo/Fe. Image is upright. "When there are no glasses in the tube, the rays proceed to the object FG along the straight lines ECF and EDG, but with the glasses put in they proceed along the refracted lines ECH and EDI. They are indeed squeezed together and where before, free, they were directed to the object FG, now they only grasp the part HI"

12. Galileo begins a revolution.. He then turned his telescope to the Heavens… His initial version had magnification of 8x but was soon refined to the 20x

13. Galileo could see stellar occultation, mountains on Moon, and so on. At one stroke he could change the way the Moon looked. January 19, 1610 stellar occultation

14. He observed that some parts of the Moon were illuminated well before its surroundings by the sunlight. We know that mountain tops are illuminated at the dawn well before the valleys. He built a convincing case for the reality of the mountains by sketching the appearance of parts of the Moon’s surface at different times of the month, that is, under different angles of lighting. Obviously this caused an uproar. The orthodox were enraged, how can Galileo claim that Moon, an celestial body to be ‘imperfect’ ?!

15. Sun is blemished, changing, and rotating

16. Galilean Moons Galileo’s next major discovery began with his observation on January 7, 1610, of what he took to be a rather odd set of three small fixed stars near Jupiter. These ‘stars’ were invisible to the naked eye. Observations over successive night revealed that actually four star-like objects in a line with it. The objects moved from night to night, sometimes disappearing behind or in front of the planet. Galileo correctly inferred that these objects were moons of Jupiter and orbited it just as our Moon orbits Earth. By the 15th January 1610 had realized that he was looking at moons of Jupiter.

17. Through naked eye Through telescope Galileo then turned his attention to most numerous objects in the night sky- stars. Rather to his disappointment the stars showed no features- they were still point source, even through a telescope the stars still appeared as points of light. Galileo suggested that this was due to their immense distance from Earth. On turning his telescope to the band of the Milky Way Galileo saw it resolved into thousands of hitherto unseen stars. In like manner when ex explored the region of Pleiades, he found stars that were unseen to naked eye. His exploration of the Orion nebula also revealed unseen stars.

18. Galileo Galilei published Sidereus Nuncius, or the 'Starry Messenger ' in March 1610. In it he provided a lively and accessible account of his telescopic observations. This revolutionized the astronomy – in fact all the sciences.

19. Copernicus Galileo’s drawing of the phases of Venus and modern photo-mosaic Ptolemy Observation of the phases of Venus helped establish the heliocentric theory on a firm footing.

20. His telescopic observation of Saturn resulted in total shock. Initially Saturn appeared to have ears, and latter some kind of appendage. Galileo could not make sense of it. Few decades later, Huygens using a better telescope resolved it as a ring around Saturn. In any case Galileo’s observation showed that stellar objects need not be perfect sphere.

21. Galileo's extensive telescopic observations of the heavens made it more and more plausible that they were not made from a perfect, unchanging substance. In particular, Galileo's observational confirmation of the Copernican hypothesis suggested that the Earth was just another planet, so maybe it was made from the same material as the other planets. It was radical and an epistemic rupture of celestial and terrestrial. Same laws of physics applied in both cases. One set of science is all that is required to explain ‘heaven and Earth’!

22. Just as Aryabhata was condemned for his views against the purnaic myth of Rahu - Ketu, Galileo was punished by the orthodoxy in Europe for daring to put forth his theories. He was to suffer for many years for upholding science and spirit of quest against mindless dogmas.

23. In July 1633, he was imprisoned and latter his sentence was converted into life-long house arrest, because of health reasons. He was not allowed to have contact with the outside world. Until his death, even at his old age he kept working.

24. Down but not Out Although Galileo was ill and mentally exhausted, he started to write a book about mechanics, based on his research in Padua. This book, Discorsi, or Dialogues Concerning Two New Sciences was published by Elzevier in Leiden, because it could, of course, not be published in Catholic lands. The book convincingly argued against the Earth-centered universe and upheld the scientific spirit. No wonder the 400th annivesary of Galileo’s use of telescope is celebrated as International Year of Astronomy.

25. JOHANNES KEPLER 1571 to 1630 A useful resource: http://kepler.nasa.gov/johannes

26. 1600: Meets Tycho Brahe; 1601: Imperial Mathematicus Born: 27 Dec 1571 Weil der Stadt 1594-1600: Teacher of astronomy & mathematics at the Protestant School in Graz

27. Optics Mathematics: logarithms, calculus Astronomy The last scientific astrologer

28. Kepler published First two Laws of Planetary Motion in 1609 – A Fact not much publicized!This too exactly 400 years ago!

29. It’s the Law!

30. Planetary orbits are ellipses, with the Sun at one focus. Planets sweep out equal areas in equal times

31. 1619: Third Law of Planetary Motion 1618: 3rd Law of Planetary Motion

32. Kepler's Third Law quantifies the observation that more distant orbits have longer periods: a 3 = P 2 Here, the semimajor axis a is measured in A.U. and the orbital period P is measured in years.

33. 1618: 3rd Law of Planetary Motion P2 = a3

34. Standing on the shoulders of Johannes Kepler,through the analysis of Kepler’s Laws of Planetary Motion, Isaac Newton discovered the Law of Universal Gravitation.

35. Issac Newton built a telescope from mirrors, not lenses Reflecting telescopes solved the problem of colored images obtained with lenses, and other problems as well!

36. Reflecting Telescope: Schematic Diagram A telescope in which light from the object is gathered and focused by a concave mirror, with the resulting image magnified by the eyepiece. A concave mirror reflects the light and brings it to a focus to form a small inverted image In both, refracting and reflecting telescopes, image formed will be inverted, but this can be re-inverted by using extra lens. But this would not be required in astronomical telescopes.

37. Recording what we see Photographic film: in 1850, the first permanent images recorded, but wet emulsions were very slow, and long exposures were needed “dry” emulsions made astrophotography much easier! Which ushers us into the modern era… First image of the Moon, 1852

38. Telescopes are light buckets! The greater the diameter of the lens or mirror, the more light it collects - and the fainter the object we can see Stars seen with larger and larger telescopes

39. An older Refracting Telescope The 0.9 meter Lick Refractor on Mt. Hamilton, CA

40. versus a 35 year old reflecting telescope The 4 meter telescope at Kitt Peak

41. versus a very modern and large Reflecting Telescope The 8 meter Gemini North telescope at Mauna Kea

42. The largest single telescope for visible and infrared light in the world today is the Great Canary Telescope situated at La Palma, Canary Islands, with the main mirror 10.4 m (410 inches) in diameter.

43. Asia’s largest telescope of 2.34 meter diameter It is located at 175 km away from Bangalore, at Kavalur in TN Observing nights are comparatively large in number It is operated by Indian Institute of Astrophysics Vainu Bappu Telescope

44. World’s highest telescope(4.5km) located at Hanle in J & K Telescope works in optical and Near Infrared region of EMR Himalayan Chandra Telescope It is remotely operated by Indian Institute of Astrophysics Aperture is 2 metres with Alt-azimuth mount

45. Located at the height of about 1680 m and located at Mt Abu (Rajasthan) Telescope works in near- infrared and optical regions. Aperture is 1.2 m. Operating since 1994. It is operated by Physical Research Laboratory, Ahmedabad Gurushikhar Telescope

46. Undoubtedly… Telescope is a striking example of how technology could help push the frontiers of science further ahead; and help improve our understanding of the natural phenomena.

47. Discoveries with telescopes from the 1600s through the 1800s laid the foundations for modern astronomy. 13 March 1781 Uranus was discovered by William Hershel and his sister Carolina.

48. Neptune was discovered by Adams and Leverrier by mathematically calculating where it should be from the gravitational perturbation it caused on the path of Uranus. It was discovered in 1846. Thus it has not even completed one round about sun since its discovery.

49. Next, the asteroids between the orbits of Mars and Jupiter were discovered.Between the orbit of Mars and Jupiter there are numerous space rocks of varying sizes. These together are called asteroids or minor planets.

50. Asteroids are composed of rocks and boulders bound together due to gravity and the surface is covered with fine dust