Astronomy 1140 -- Autumn 2018 (Prof. Stanek)
Midterm 1 Study Guide (Friday, September 21)
--------------------------------------------

Please bring your OSU ID with you.

There will be 50 questions on the Midterm Exam, which will count for
19% of the final grade.

As an option, we allow one "help sheet" (one standard 8.5x11 piece of
paper, both sides can be used) of self-prepared (you can use a
computer) notes to be used during this and following exams.  


Classes to review:

Units and Scales
Mapping the Earth and the Sky
Motions of the Sky
The Motion of the Sun
Telling Time 
The Motion of the Moon
The Calendar
The Four Seasons
Eclipses
The Wandering Planets
Greek Astronomy
Copernicus
Tycho & Kepler

Key Concepts:

The Celestial Sphere 
--------------------

(1) The sky as seen from Earth is divided into 88 constellations.
(2) It is convenient to pretend the stars are attached to a celestial
    sphere.
(3) The celestial sphere appears to rotate about the celestial poles
    (1 sidereal day).
(4) The Sun appears to move west to east relative to stars (1 year),
    its path on the sky is called ecliptic.
(5) The Moon appears to move west to east relative to stars (1 month).

Season & Calendars 
-------------------

(1) The cause of the seasons is the tilt of the Earth's rotation axis
    relative to its orbit around the Sun.
(2) The solar day is based on the time between one noon and the next.
(3) The (tropical) year is based on the time between one vernal equinox 
    and the next.
(4) The moon (month) is based on the time between one new moon and the
    next.

Moon Phases & Eclipses 
-----------------------

(1) Lunar phases change as we see more or less of the Moon's sunlit
    half.
(2) The Moon rotates about its axis as it revolves around the Earth.
(3) The sidereal month=27.3 days; the synodic month=29.5 days.
(4) A lunar eclipse occurs when the Moon passes through the Earth's
    shadow.
(5) A solar eclipse occurs when the Earth passes through the Moon's
    shadow.

Planets, Greek Astronomy, Copernicus 
------------------------------------

(1) Aristotle (4th cent BC) showed that the Earth is round.
(2) Greek astronomers developed a geocentric model for the universe.
(3) Ptolemy (2nd cent) used epicycles to explain retrograde motion of
    planers.
(4) Copernicus (16th cent) proposed a heliocentric model for the
    universe.
(5) In the model of Copernicus, retrograde motion is easily explained.

Tycho, Kepler
-------------

(1) Tycho Brahe made accurate measurements of planetary motion.
(2) Planetary orbits are ellipses with the Sun at one focus.
(3) A line between planet & Sun sweeps out equal areas in equal times.
(4) The square of a planet's orbital period is proportional to the
    cube of its average distance from the Sun.