How to determine the phase of the moon?

Question

PHP

Who can help with solving the problem from the point of view of programming in php (well, or at least in javascript)

Essence of the task: determination of the phase of the moon
1. Minimum task - determination of the current phase of the moon
2. Required task - determination of the phase of the moon for any date The

function only needs to return the results:
1. New Moon
2. Growing Moon - First quarter.
3. Growing Moon - Second quarter.
4. Full Moon
5. Waning Moon - Third Phase
6. Waning Moon - Fourth Phase.

How is this determined mathematically? Who can tell, can anyone come across a similar problem?

Answer 1

Take the exact date and exact time when the full moon was, in 29.5305882 days there will be a full moon again, etc., and count the phases of the moon.

Answer 2

bit.ly/YkwjXH Tons
of solutions.