For more information on this in Ball State's University Libraries and online:
Do keyword searches in CardCat for "vernal," "spring," "autumnal," or "fall" "equinox," or "soltices." You can also type in terms such as "astronomy" or "seasons" for more general information.
You can also find books on this subject and astronomy in general on the shelves under call numbers beginning with Q14 (encyclopedia, dictionaries, glossaries, etc.) or QB63-65 (field guides, star charts, manuals, etc.).
"The Egg and the Equinox" from Phil Plait's Bad Astronomy
Seasons Calculator for Indianapolis IN, years 2000-2049 from timeandate.com
SkyTonight Almanac from Sky & Telescope
"Everything you need to know: Vernal spring equinox 2012." from EarthSky
Earth's Seasons: Equinoxes, Solstices, Perihelion, and Aphelion from the US Naval Observatory