<?php
/* $Id: moon_phases.php,v 1.9.2.2 2007/08/06 02:28:32 cknudsen Exp $
*
* Calculate the moonphases for a given year and month.
*
* Code borrowed from http://www.zend.com/codex.php?id=830&single=1
* Modified to accept month parameter and return 1 month of moon phases
* and return array in Ymd format.
* Converted from Basic by Roger W. Sinnot, Sky & Telescope, March 1985.
* Converted from javascript by Are Pedersen 2002
* Javascript found at http://www.stellafane.com/moon_phase/moon_phase.htm
*
* Required gif images to be present in the images folder.
* newmoon.gif, fullmoon.gif, firstmoon.gif, lastmoon.gif
*
* @param int $year Year in YYYY format
* @param int $month Month in m format Jan =1
*
* #returns array $key = phase name, $val = Ymd value
*/
function calculateMoonPhases ( $year, $month = 1 ) {
$s = ''; // Formatted Output String.
$U = false;
$K0 = intval ( ( $year - 1900 ) * 12.3685 ) + ( $month - 1 );
$R1 = 3.14159265 / 180;
$T = ( $year - 1899.5 ) / 100;
$T2 = $T * $T;
$T3 = $T * $T * $T;
$J0 = 2415020 + 29 * $K0;
$F0 = ( ( 0.0001178 * $T2 - 0.000000155 * $T3 ) +
( 0.75933 + 0.53058868 * $K0 ) -
( 0.000837 * $T + 0.000335 * $T2 ) );
$M0 = $K0 * 0.08084821133;
$M0 = ( ( 360 * ( $M0 - intval ( $M0 ) ) + 359.2242 ) -
( 0.0000333 * $T2 ) -
( 0.00000347 * $T3 ) );
$M1 = $K0 * 0.07171366128;
$M1 = ( ( 360 * ( $M1 - intval ( $M1 ) ) + 306.0253 ) +
( 0.0107306 * $T2 ) +
( 0.00001236 * $T3 ) );
$B1 = $K0 * 0.08519585128;
$B1 = ( ( 360 * ( $B1 - intval ( $B1 ) ) + 21.2964 ) -
( 0.0016528 * $T2 ) -
( 0.00000239 * $T3 ) );
for ( $K9 = 0; $K9 < 7; $K9 += 0.5 ) {
$J = $J0 + 14 * $K9;
$K = $K9 / 2;
$B6 = ( $B1 + $K * 390.67050646 ) * $R1;
$M5 = ( $M0 + $K * 29.10535608 ) * $R1;
$M6 = ( $M1 + $K * 385.81691806 ) * $R1;
$F = ( ( $F0 + 0.765294 * $K9 ) -
( 0.4068 * sin ( $M6 ) ) +
( ( 0.1734 - 0.000393 * $T ) * sin ( $M5 ) ) +
( 0.0161 * sin ( 2 * $M6 ) ) +
( 0.0104 * sin ( 2 * $B6 ) ) -
( 0.0074 * sin ( $M5 - $M6 ) ) -
( 0.0051 * sin ( $M5 + $M6 ) ) +
( 0.0021 * sin ( 2 * $M5 ) ) +
( 0.0010 * sin ( 2 * $B6 - $M6 ) ) +
( 0.5 / 1440 ) );
$J += intval ( $F );
$F -= intval ( $F );
//.
// Convert from JD to Calendar Date.
$julian = $J + round ( $F );
$s = ( function_exists ( 'jdtogregorian' )
? date ( 'Ymd', strtotime ( jdtogregorian ( $julian ) ) )
: jd_to_greg ( $julian ) );
// .
// half K
if ( ( $K9 - floor ( $K9 ) ) > 0 )
$phases[$s] = ( $U ? 'first' : 'last' );
else {
$phases[$s] = ( $U ? 'full' : 'new' );
$U = ! $U;
}
} // Next
return $phases;
} //End MoonPhase
// .
// Function borrowed from http://us3.php.net/manual/en/function.jdtogregorian.php
// Used if calendar functions are not compiled in php.
function jd_to_greg ( $julian ) {
$julian -= 1721119;
$calc1 = 4 * $julian - 1;
$year = floor ( $calc1 / 146097 );
$julian = floor ( $calc1 - 146097 * $year );
$day = floor ( $julian / 4 );
$calc2 = 4 * $day + 3;
$julian = floor ( $calc2 / 1461 );
$day = $calc2 - 1461 * $julian;
$day = floor ( ( $day + 4 ) / 4 );
$calc3 = 5 * $day - 3;
$month = floor ( $calc3 / 153 );
$day = $calc3 - 153 * $month;
$day = floor ( ( $day + 5 ) / 5 );
$year = 100 * $year + $julian;
if ( $month < 10 )
$month += 3;
else {
$month -= 9;
$year++;
}
return sprintf ( "%04d%02d%02d", $year, $month, $day );
}
?>