|image from WikiCommons|
7:09 pm Eastern Daylight Saving Time, 20 June 2012 marks the summer solstice- the longest day of the year.
This means that the sun appears furthest north in the sky and the time between sunrise and sunset is the greatest providing the most daylight hours for the whole year. For example, sunrise was 6:12 am this morning and sunset will be 9:15 pm. On 22 September, the autmunal equinox three months from now, sunrise will be 7:30 am and sunset will be 7:38 pm (do your own calculations at the US Naval Observatory)- almost 3 hours more daylight (2 hours, 55 minutes, to be exact).
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" and "Shall I compare thee to a summer's solstice?" from Phil Plait's Bad Astronomy
"The Longest Day", GreenwichMeanTime.com
"Summer Solstice" from Wolfram Research
SkyTonight Almanac from Sky & Telescope
Earth's Seasons: Equinoxes, Solstices, Perihelion, and Aphelion from the US Naval Observatory
First Day of Summer, Old Farmer's Almanac