A Brief, Abbreviated Review Synopsis of Subjects Covered
in Astro 150
Part I
- Scales of the Universe
- Size of solar system
- Definition of the light year
- The nearest: star, galaxy
- The composition and age of the Universe
- Gravity: Newton's Laws
- Gravity as a fundamental force: Central, Universal, and
Cosmic
- Other Cosmic forces: Electromagnetic force, Weak
Nuclear force, strong nuclear force
- Light: a form of energy=electromagnetic radiation
- wave nature: wavelength (l) x frequency (f) = speed (c for
light)
- different wavelength = different 'color'
- particle nature: photon as a bundle of light energy; energy
proportional to frequency
- Brightness proportional to luminosity divided by distance
squared
- Electromagnetic spectrum
- short wavelength (gamma ray) to long wavelength (radio)
- high energy (gamma ray) to low energy (radio)
- Thermal (blackbody) radiation - radiation from objects because
they are hot
- Wien's law: wavelength of maximum emission increases with
decreasing temperature
- Stefan-Boltzmann Law: energy emitted proportional to
T4
- stars are like blackbodies; hot stars are blue, cool stars
are red
- Spectral Lines
- Kirchoff's laws: emission, absorption, and continuous
spectra
- discrete atomic energy levels correspond to discrete
electron orbits
- transitions up in energy absorb photons; transitions down
emit photons
- bigger energy difference between levels, higher energy
photon involved
- each element has its own signature spectral lines; atomic
fingerprints
- Spectroscopy as the "Rosetta Stone" in astronomy
- Telescopes:
- light gathering power depends on size2
- resolution depend on size / wavelength
- mechanical and optical specifications
- instrumentation: photometry, spectroscopy, imaging
- advantages and disadvantages of astronomy from space
- adaptive optics
- The Sun
- surface features: sunspots, prominences, corona, etc.
- energy transport by radiation, conduction and convection
- energy production by nuclear fusion: E=mc2; 4 hydrogen
-> 1 helium + energy
- solar neutrino problem