note 83903 added to function.date-sun-info

It should be noted that for extreme geographical locations date_sun_info() might return unexpected values. Values of 1 or empty may be returned. If you are expecting a unix timestamp this will default to the epoch, or epoch+1, which is not what you would expect. After researching official almanac records for these locations it appears likely that for sunrise and sunset return values of 1 relate to a situation where the sun is above the horizon for the entire 24 hour day. It is also possible that empty return values relate to a situation where the sun is below the horizon for the entire 24 hour day. In the case of twilight data a 1 probably means that the sun never dips below that zenith, and an empty value means the sun never rises above said zenith for that given day. The following code exhibits unique dates from the northernmost city Ny-Ålesund, Svalbard, and the southernmost city McMurdo Research Station, Antarctica. <?php $northernmost_city_latitude = 78.92; // Ny-Ålesund, Svalbard $northernmost_city_longitude = 11.93; $southernmost_city_latitude = -77.88; // McMurdo Research Station, Antarctica $southernmost_city_longitude = 166.73; print_r( date_sun_info( strtotime("2008-01-01") , $northernmost_city_latitude, $northernmost_city_longitude) ); print_r( date_sun_info( strtotime("2008-04-01") , $northernmost_city_latitude, $northernmost_city_longitude) ); print_r( date_sun_info( strtotime("2008-01-01") , $southernmost_city_latitude, $southernmost_city_longitude) ); print_r( date_sun_info( strtotime("2008-06-01") , $southernmost_city_latitude, $southernmost_city_longitude) ); ?> This will return the following. Observe that sometimes a value of 1 or empty is returned. Array ( [sunrise] => [sunset] => [transit] => 1199186158 [civil_twilight_begin] => [civil_twilight_end] => [nautical_twilight_begin] => 1199184075 [nautical_twilight_end] => 1199188241 [astronomical_twilight_begin] => 1199170475 [astronomical_twilight_end] => 1199201840 ) Array ( [sunrise] => 1207019232 [sunset] => 1207077865 [transit] => 1207048548 [civil_twilight_begin] => 1 [civil_twilight_end] => 1 [nautical_twilight_begin] => 1 [nautical_twilight_end] => 1 [astronomical_twilight_begin] => 1 [astronomical_twilight_end] => 1 ) Array ( [sunrise] => 1 [sunset] => 1 [transit] => 1199148994 [civil_twilight_begin] => 1 [civil_twilight_end] => 1 [nautical_twilight_begin] => 1 [nautical_twilight_end] => 1 [astronomical_twilight_begin] => 1 [astronomical_twilight_end] => 1 ) Array ( [sunrise] => [sunset] => [transit] => 1212281461 [civil_twilight_begin] => [civil_twilight_end] => [nautical_twilight_begin] => 1212273312 [nautical_twilight_end] => 1212289609 [astronomical_twilight_begin] => 1212264187 [astronomical_twilight_end] => 1212298734 ) ---- Server IP: 64.71.164.2 Probable Submitter: 66.114.157.237 ---- Manual Page -- http://www.php.net/manual/en/function.date-sun-info.php Edit -- https://master.php.net/note/edit/83903 Del: integrated -- https://master.php.net/note/delete/83903/integrated Del: useless -- https://master.php.net/note/delete/83903/useless Del: bad code -- https://master.php.net/note/delete/83903/bad+code Del: spam -- https://master.php.net/note/delete/83903/spam Del: non-english -- https://master.php.net/note/delete/83903/non-english Del: in docs -- https://master.php.net/note/delete/83903/in+docs Del: other reasons-- https://master.php.net/note/delete/83903 Reject -- https://master.php.net/note/reject/83903 Search -- https://master.php.net/manage/user-notes.php