von Nick Strobel (in englischer
Frame Version über die Elementary Astronomy Originalseite
as a Science and a Sense of Scale. I
introduce astronomy's place in science, and give a sense
of the size and time scales involved.
for Finding Scientific Truth.
Borrowing from Pine's book ``Science and the Human
Prospect'' I discuss the scientific method, correlations,
problem of induction, positivism, levels of testimony,
empiricism, models correspondence with reality.
Without a Telescope. I
discuss the celestial sphere, motions of the Sun (solar
and sidereal days, time zones, equation of time, and
seasons), motions of the Moon (phases and eclipses), and
of Astronomy. I focus on
the rise of modern science in Europe, from the ancient
Greeks to Kepler.
Law of Gravity. Newton's
laws of motion and his law of gravity are discussed.
Applications of those laws (esp. gravity) are covered
(e.g., measuring the masses of planets and stars, orbital
motion, interplanetary trips, tides, etc.).
Relativity. I discuss
Einstein's Special Relativity and General Relativity
theories. The concepts of spacetime and gravity as a
warping of spacetime are introduced along with
observational proofs of his theories.
Radiation (Light). General
properties of light, definition of frequency, spectrum,
temperature. Light production: Continuous (thermal)
spectra, emission lines, absorption lines and the Bohr
model for the atom. Doppler Effect and why spectral lines
must be used to measure the doppler shifts.
Covers refractors, reflectors, radio telescopes,
light-gathering power, resolving power, interferometers,
magnification, and atmospheric distortion such as seeing,
reddening, and extinction.
Science. This chapter is an
introduction to planetary science. I discuss the
techniques astronomers use to find out about the planets,
their atmospheres (what determines if an atmosphere
sticks around, the transport of energy, and appearance),
their magnetic fields (the magnetic dynamo theory), and
their interiors. In a separate section I focus on a
comparison between the atmospheres of Earth, Venus, and
Mars and why they are now so radically different from
each other (greenhouse effect, carbon cycle, runaway
refrigerator, etc.) There are links to three graphical
descriptions of the concepts covered: the
Earth-Venus-Mars comparison (a flowchart), the greenhouse
effect and the UV dissociation of water, and a flowchart
of the calculations involved in determining if an
atmosphere sticks around for billions of years. I end the
chapter with a discussion of the major moons in the solar
system and ring systems.
System Fluff. The basics of
meteorites, asteroids, and comets are introduced and how
they can tell us the ``when'' and the ``how'' of the
formation of the solar system. At the end is an
exploration of the other planetary systems.
Star Properties. Notes for
the properties of stars and how we determine them. Things
like distances to stars, their masses, radii, composition
and speeds. Also HR diagram, spectral types, and
spectroscopic parallax. The dangers of selection effects
and biased samples are also discussed with the
application of finding what a typical star is like.
Sun and Stellar Structure. This
chapter covers: The Sun, interiors of stars, and nuclear
fusion, neutrinos, the solar neutrino problem, and
helioseismology. The concept of hydrostatic equilibrium
is used to explain the mass-luminosity relation and the
reason for the mass cut-off at the high and low ends.
and Deaths of Stars. This
chapter covers: stellar evolution (all nine stages) and
stellar remnants (white dwarfs, neutron stars, black
Interstellar Medium and the Milky Way.
This chapter covers: the dust and gas between the stars
and how we use the 21-cm line radiation to map the
Galaxy. Also, the structure of the Milky Way Galaxy, our
place in it, and how we determine these things. The
rotation curve and the existence of the dark matter halo,
stellar populations, and the galactic center are also
Galaxies and Active Galaxies. This chapter
covers: the characteristics of other normal galaxies,
active galaxies, and finding distances to other galaxies
(this includes the distance-scale ladder). Also,
large-scale structure is covered (galaxy clusters and
collisions and superclusters).
This chapter covers cosmology: the study of the nature,
origin, and evolution of the universe as a whole. The
distance-scale topic is dealt with in the Steps
to the Hubble Constant document. I discuss
Olbers' Paradox, the cosmic microwave background
radiation, the fate of the universe (open or closed),
dark matter, inflation, and the cosmological constant.
Beyond the Earth. This chapter covers:
lifezones, types of stars to focus on in the search for
suitable planets, basic definitions of life, the kind of
planet where we think life would likely arise, and
finally the frequencies we use in the Search for
Extra-Terrestrial Intelligence (S.E.T.I.).
Momentum in Astronomy. I
define angular momentum and give several examples of
angular momentum in astronomy: Kepler's second law of
orbital motion, Earth-Moon system, rapidly spinning
neutron stars, accretion disk in a binary system, and a
collapsing galactic cloud.
Mathematics Review. Here's a quick run
through some basic mathematics: working with fractions
and percentages, exponents, roots, powers of ten, working
with really BIG or really small numbers---scientific
notation and the metric system. I assume that the reader
has had this stuff before, so the quick run through will
be sufficient to jog the dormant memory.
Astronomy constants, physical constants, planets (orbital
properties, physical characteristics, atmospheres), 100
nearest stars, and 100 brightest stars as seen from the
Definitions of astronomy terms used in this web site.
Elementary Astronomy Originalseite
Physical Science Dept.
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