Answer:
   
   The night ends at "Alot haShachar", the "rising of the morning". It
   has two halachic definitions: Most rule it is 72 minutes before dawn,
   some use the solar equivalent--16.1o (degrees) below the horizon. The
   latter would come dawn+72 min if the sun were up for exactly 12 hours
   that day. In the summer it would be longer, in the winter, later.
   Others use 90 solar minutes.
   
   The earliest you can say the morning blessings is Alot. The earliest
   one can wear tzitzit is at "Misheyaqir", when "one can recognize"
   which of the tzitzit strings are uncolored, and which are blue. (When
   the proper blue dye used for tzitzit was / will be available.)
   Misheyaqir also has two definitions: 11 degrees below the horizon or
   50 standard minutes. The first is the norm.
   
   Since you are supposed to wear tzitzit and tefillin for Shema, Shema
   must be said after Misheyaqir as well. The Amidah must be said at or
   after Haneitz haChamah, the sparkling of the sun, i.e., sunrise. This
   is when the leading edge of the sun is at the horizon.
   
   If you're checking your newspaper, you should find out if they're
   publishing the time the leading edge of the center of the sun crosses
   the horizon. If you say Shema well before Haneitz, you will have to
   say it again as a lead-in to the Amidah. However, this may mean that
   you can say it with tallit and tefillin at Haneitz, and then say it
   again with the Amidah without equipment.
   
   There are a number of packages out there that show you these times for
   various locales. At the Aishdash site
   ([5]http://www.aishdas.org/kaluach), there is a front end to Kaluach's
   JavaScript sunrise calculator. It's kind of unweildy, but it is
   accurate within a couple of minutes for locations well below the
   arctic circle.