Transcript 3Sept103_14_actual

Astronomy 103
Lecturer: Prof. Alex Lazarian
Office Location: 6289 Chamberlin Hall
Email:
[email protected]
Website: http://www.astro.wisc.edu/~lazarian/ast103_2014/
Office Hours: Mon. 11am-1pm, Wed. 11am-1pm. Meetings at a different time can also be arranged.
Course Reading: Pathways to Astronomy Schneider & Arny 4nd edition
Exams:
training exam -- 0% (Oct. 6)
1st exam – 25% (Oct. 15)
2nd exam—25% (Nov. 10)
final exam—30% (Dec. 15)
total for homework, quizzes, presentations -- 20%
0th
Main Ideas to be covered:
*Subject of astronomy (Units 1--4)
*Observations of planets and stars (Units 5--12)
*Laws of gravity, dark matter (Units 14-20)
*Light, atoms, spectra (Units 21--30)
*Stars: Sun as an example (Units 49--50)
*Learning about stars (Units 52--55)
*Birth and evolution of stars (Units 56—63, 69)
*When the fuel begins to run out (Units 64--66)
*Supernova, neutron stars and black holes (Units 67--68)
*Galaxies and quasars (Units 74--77)
*Our galaxy- Milky Way (Units 70--73)
*The expanding Universe (Units 78--82)
*Life in the Universe (Units 83--84)
*Review of the course
Prof. V. Ginzburg
V. Ginzburg
My PhD is from
Cambridge University
Martin Rees
Why do I study Astronomy?
“Education is kindling of a flame, not the filling of a vessel”
Socrates
My goals for the course:
•
•
•
•
Share my excitement with Astrophysics
Provide a survey of most of Astronomy
Show that Astronomy is a quest for our origins
Show how science is done
Look at my personal web page to know more about my research
http://www.astro.wisc.edu/~lazarian/
The Earth
• The Earth is a planet, a body in
orbit around a star (The Sun)
• Radius: 6371 km (3909
miles)
• Mass: around 6 billion
trillion tons
• Actual value:
5,970,000,000,000,000,000,000,000 kg
• Too many zeros!
Use 5.97  1027 kg, instead!
Metric System
•Easier to use (everything is a factor of 10!)
The Moon
• The Moon is a satellite, a
body orbiting a planet
– Rocky world, littered with
craters
• Bombarded by meteors
• Where are the Earth’s craters?
– Smaller than the Earth
• Less than 1/80 the mass
• ¼ the diameter of Earth
– Small, so cooled quickly!
– Cold, airless and lifeless
The Planets
Why are they so
different?
How did they
get this way?
• Wide variety of planets in the Solar System
–
–
–
–
Rocky, hot and airless worlds
Gas giants and ringed wonders
Cold planets of blue methane
Tiny icy bodies
The Sun
• The Sun is a star, a
huge ball of gas held
together by gravity and
generating light
through thermonuclear
reactions
• Source of all energy in
the Solar System
• 100x wider than the
Earth, and 300,000x as
massive!
• Young, yet old
– 4 billion years old
– Will last another 5 or
6 billion years
The Solar System
•
•
•
•
Planets, asteroids, comets and dust all held together by the Sun’s gravity
Everything goes around the Sun on elliptical paths called orbits
All orbits lie in the same plane, like peas rolling around on a dinner plate
Too big to describe using meters – we need something more convenient
A convenient measure –
the Astronomical Unit
• It is convenient to measure planetary
distances using the Astronomical
Unit, or AU
• 1 AU = average distance between
the Earth and the Sun
• 1 AU ~ 150 million km
Some planetary distances:
• Mercury: 0.4 AU
• Mars: 1.5 AU
• Saturn: 10 AU
• Pluto: 40 AU