This section of the course is based mainly on material in the
first three chapters in the 5th and 6th
editions (Prologue and Chapters 1, 2 and 3 of the 4th
edition) of the textbook,"In Quest of the Universe".
In the outline below, I indicate the material you should read and which of the
terms that are highlighted in bold face or italics you should know.
Chapter 1 - An Earth-Centered Universe
Chapter 3 - Gravity and the Rise of Modern
Astronomy
- Introduction
- 3-1 Galileo Galilei and the Telescope:
observing the Moon, the Sun and the stars, Jupiter's moons, Galilean moons,
Galileo Galilei, the phases of Venus, full, gibbous, crescent, quarter, see
also Figure 1-24 to compare with phases of the Moon
Interesting background information on Galileo can be found
at http://galileo.rice.edu/ . (This
is for interest and understanding, not extra examinable material!)
- 3-2 Isaac Newton's Grand Synthesis:
Newton's first two laws of motion, inertia, acceleration, force, Isaac Newton,
an important digression - mass and weight, back to Newton's second law,
Newton's third law, action, reaction
- 3-3 Motion in a circle: centripetal force
- 3-4 The Law of Universal Gravitation:
weight, arriving at the law of universal gravitation, inverse square law.
- 3-5 Newton's laws and Kepler's Laws: travel
to the Moon, binary systems, Newton's expansion of Kepler's third law (relating
mass, semimajor axis, orbital period). Note Figures 3-16 (p.86 in 6th ed.)
- 3-6 Orbits and the Centre of Mass: centre
of mass, barycentre
- 6-2 (4th Ed.: 3-7) The Tides: differential gravitational
pull, spring tides, neap tides, tidal friction.[Discussion in 4th Ed. more
complete]
Rotation and revolution of the Moon; precession of the Earth.
Short Readings from Other Chapters
- In addition to the readings from chapters 1
to 3, we discuss a few brief sections from subsequent chapters. These
illustrate the importance of Newton's law of gravitation and his expansion of
Kepler's third law.
- Cometary orbits - Isaac Newton and Edmund Halley (page
285-286 [334-341 in 5th ed.] in
chapter 10). Sections {\bf 10-4 and 10-5
(6th,5th,4th eds.)}: the nature of comets and the Oort and Kuiper clouds.
Additional material is given in the lecture notes.
See Wikipedia on: Comets, Oort Cloud for interesting information and explanations.
- William Herschel, Musician/Astronomer: telescope builder, the
discovery of the planet Uranus, discovery (with the help of his sister
Caroline) of the existence of stars in orbit around one another (binary stars)
- pages 267, 354-357 (307 4th ed.) in chapter 9.
- Further discussion of the discovery of binary stars, in
particular, visual binaries - pages 357-353
(379-380 5th ed., 410 and 411 4th ed.) in chapter 12,
including Figures
12-23 to 12-25 (Fig. 12-26 in 4th ed.). If the orbital period and the
mean separation of the two stars can be
derived, the total mass of the system can be calculated from Newton's extension
of Kepler's third law (see page 84 [p.87 in 5th ed. ; p.80 in 4th ed.]).
If each star's distance from the
barycentre can be derived, the individual masses can be calculated (see Example).
- The Discovery of Neptune - page 271 [5th ed.:p.289; 4th ed.:p.314]
in section 9-4.
- The Mass of the (Milky Way) Galaxy: section 16-2 in chapter
16 (all 3 eds.).
The point here is to understand how Newton's extension of Kepler's
third law can be used to derive the mass (see the discussion on pages 520-522).
Even though the period of the revolution of a star around the centre of the
Galaxy can not be directly measured, it can be estimated from the star's speed
and its distance from the galactic centre. Another point to note is that Figure
16-13b demonstrates that about 90% of the mass of the Galaxy is not visible.
- The Masses of Galaxies: section 17-3 in chapter 17.
In
this section, you should understand the three methods for determining masses of
other galaxies. These are explained on pages
491-493 [5th ed.:556-558] and all of them are based
on Newton's extension of Kepler's third law. You should also understand the
term, dark matter. All of the methods for deriving galactic masses
have demonstrated the presence of dark matter.
- Lecture Notes 1-8 are posted on Blackboard in PDF .
MATERIAL UP TO HERE IS EXAMINABLE IN THE FIRST TEST
Material on the speed of light we will leave to the second Term Test.
*** (The following item on Neptune is for interest only: There is an
interesting addendum to the story as told in your textbook. Some important
correspondence was stolen from the Royal Greenwich Observatory in the mid 1960s
and was not recovered until the late 1990s. It indicates that perhaps Adams was
not as good nor Airy as bad as the "traditional" story indicates. A website at
University College London:
Neptune's
Discovery documents this. There was also an article "The Case of the
Pilfered Planet: Did the British steal Neptune?" in the December 2004 issue of
Scientific American. It turns out that the first person to record a
telescopic observation of Neptune was Galileo. In 1613,
the planet
Jupiter occulted Neptune and Galileo used Neptune as a reference star on
two occasions when he was studying the motions of the principal moons of
Jupiter.) ***
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