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Astronomy 1X
Dynamical Astronomy
Dr G. Woan
Room 312, Kelvin Building.
9 lectures, starting Friday 29 September
2006
This course introduces
the student to Newtonian Gravitation, and its application to simple
two body problems. We will cover ideas of force, energy, momentum,
and angular momentum as applied to the motion of a body in a gravitational
field, and explore how the parameters of the orbit cam be deduced
from observations of the motion.
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Course details and lecture notes
Handouts
Question sheets
Recommended books
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Course details
Copies of lecture notes will appear here as the course proceeds. They are for
reference only, and should not be used to replace your own lecture notes. You
will find the course much harder if you don't create your own written version,
so please do not print these notes out in quantity.
Introduction Motion under gravity; gravity as a long range force; Newton's
Law of Universal Gravitation; gravitational attraction of spherical bodies;
1, 2 and n-body interactions; Kepler's Laws of planetary motion
Pictures: [ galaxy M83 | globular
cluster 47 Tuc ]
Handouts:[ quick facts #1: orbital motion | force
from a spherical body (not examinable) | Newton's
Principia ]
Animations[ Newton's cannon | Eros
| Eros flyover ]
Planetary motion Newton's laws of motion; linear momentum;
circular motion; angular velocity; certripetal acceleration; orbital period;
Kepler's laws derived for circular orbits; natural units for the solar system;
geostationary orbits; angular momentum
Applets: [satellite
positions in 3D ]
Elliptical orbits Conic sections (ellipse, circle, hyperbola);
properties of the ellipse; aphelion and perihelion; response of orbits
to an impulse; semi-latus rectum
Pictures: [ conic sections | comet
Encke ]
Applets: [ comet Encke
]
Conservation laws Idea of conserved quantities; energy; momentum; angular
momentum; gravitational potential energy (general and at small heights);
virial theorem; escape velocity; orbital velocity law derived
Applications Relationship between semi-major axis and energy; equation
of the ellipse; proof of K1; relation between angular momentum and semi-latus
rectum
Handouts: [ Kepler's 1st law from Newtonian dynamics
(not examinable)]
Hohmann transfer orbits As the 'most efficient' transfer orbit;
example of LEO-->GEO; transfer times and delta-vees; example of Earth-->Mars
transfer
sites: [ Mars Global Surveyor
(transfer orbit example)]
Picture: [ MGS
transfer orbit | Venus
Express transfer orbit ]
Rockets Gravity assist; examples of Voyager and Cassini;
the rocket equation
Pictures: [ Cassini | Cassini
flightpath ]
The two-body problem Form of two-body orbits; relative
motion; reduced mass and radius vector
Handouts:[ quick facts #2: The two-body problem ]
Learning Objectives: On completion of this course, the student should
be able to apply the basic concepts of Newtonian gravitation and motion and
use these concepts quantitatively. In particular the student will be able to carry out
dynamical calculations for planetary, stellar and spacecraft
orbits corresponding to the planar 1 and 2 body problems.
Handouts
Extra copies
of the handouts are available from the astronomy secretary's office (room 608)
as they appear in the course. All are reproduced above in pdf format.
Question Sheets
Problems for this course can be found in the A1
problems handbook. See the A1
Astronomy Home Page.
Books
There is no single textbook which is an essential purchase for
this module. However An
Introduction to Modern Astrophysics, B W Carroll and D A Ostlie, Addison Wesley
is strongly recommended, and is essential for the Astronomy 2 course It has
its own website here. Its approach
is in places more advanced than required for A1X and Y, however there is much
useful material in it.
Astronomy
- Principles and Practice, 4th Edition, A E Roy & D Clarke, IoP
Publishing will also be of great help. This is abrand new version of an excellent
book - also useful for positional astronomy and instrumental courses.
For wider background reading, students may find the following
list useful:
- Feynmann Lectures on Physics, volume 1, chapter 7 (worth a
look)
- Fundamental
Astronomy - 2nd Enlarged Edition, H Karttunen et al, Springer -Verlag
- The
Dynamic Universe, 4th Ed, T P Snow, West Publishing Co
- Oxford Dictionary Of Astronomy, Ed. Ian Ridpath, Oxford University
Press