datetime - Calculating Summer/Winter Solstice in PHP? -

php allows me check sunrise , sunset times day @ specific latitude & longitude.

is there simple way calculate day solstice? mean - @ specific location, day has hours of sunlight , has least?

i wouldn't call "simple", thought calculating time differences between sunrise , sunset in each day, storing data in array, , finding min/max value. iv'e made quick, hope useful:

(i used random long/lat)

function solstice() {      // set timezone     date_default_timezone_set('utc');     $date='2014/01/01';      $end_date='2014/12/31';     $i = 0;     //loop through year     while(strtotime($date)<=strtotime($end_date)) {          $sunrise=date_sunrise(strtotime($date),sunfuncs_ret_double,31.47,35.13,90,3);         $sunset=date_sunset(strtotime($date),sunfuncs_ret_double,31.47,35.13,90,3);         //calculate time difference         $delta = $sunset-$sunrise;         //store time difference         $delta_array[$i] = $delta;         //store date         $dates_array[$i] = $date;         $i++;         //next day         $date=date("y-m-d",strtotime("+1 day",strtotime($date)));     }      $shortest_key = array_search(min($delta_array), $delta_array);     $longest_key = array_search(max($delta_array), $delta_array);      echo "the longest day is:".$dates_array[$longest_key]. "<br />";     echo "the shortest day is:".$dates_array[$shortest_key]. "<br />"; }