Use date of brith to show zodiac sign

I am trying to show Zodiac sign next to birthday on user profile.
Well, the following code shows the birthday of the user

<?php echo $this->render( 'fields' , 'user' , 'profile' , 'profileHeaderA' , array('BIRTHDAY' , $user ) ); ?>

I am going to use the following code to calculate zodiac sign:

if     ( ( $month == 3 && $day > 20 ) || ( $month == 4 && $day < 20 ) ) { $zodiac = "Aries"; } 

   elseif ( ( $month == 4 && $day > 19 ) || ( $month == 5 && $day < 21 ) ) { $zodiac = "Taurus"; } 

   elseif ( ( $month == 5 && $day > 20 ) || ( $month == 6 && $day < 21 ) ) { $zodiac = "Gemini"; } 

   elseif ( ( $month == 6 && $day > 20 ) || ( $month == 7 && $day < 23 ) ) { $zodiac = "Cancer"; } 

   elseif ( ( $month == 7 && $day > 22 ) || ( $month == 8 && $day < 23 ) ) { $zodiac = "Leo"; } 

   elseif ( ( $month == 8 && $day > 22 ) || ( $month == 9 && $day < 23 ) ) { $zodiac = "Virgo"; } 

   elseif ( ( $month == 9 && $day > 22 ) || ( $month == 10 && $day < 23 ) ) { $zodiac = "Libra"; } 

   elseif ( ( $month == 10 && $day > 22 ) || ( $month == 11 && $day < 22 ) ) { $zodiac = "Scorpio"; } 

   elseif ( ( $month == 11 && $day > 21 ) || ( $month == 12 && $day < 22 ) ) { $zodiac = "Sagittarius"; } 

   elseif ( ( $month == 12 && $day > 21 ) || ( $month == 1 && $day < 20 ) ) { $zodiac = "Capricorn"; } 

   elseif ( ( $month == 1 && $day > 19 ) || ( $month == 2 && $day < 19 ) ) { $zodiac = "Aquarius"; } 

   elseif ( ( $month == 2 && $day > 18 ) || ( $month == 3 && $day < 21 ) ) { $zodiac = "Pisces"; }

How do I extract month and day from

array( 'BIRTHDAY'' , $user )