in reply to Question about Astro::Coord::ECI::Moon and "phase"

Would this be clearer as the first two paragraphs of the phase() documentation?

This method calculates the current phase of the moon and its illuminated fraction. If the time is omitted, the current time of the $moon object is used.

The phase is returned as a number from 0 to 2 * PI radians, with 0 being New Moon, PI / 2 being First Quarter, and so on. The illuminated fraction is a number from 0 (New Moon) to 1 (Full Moon).

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Re^2: Question about Astro::Coord::ECI::Moon and "phase"
by Cody Fendant (Hermit) on May 12, 2014 at 00:43 UTC

    That is sensible. But the "aha!" moment for me was when I realised that if the moon was 50% illuminated, I didn't know which 50% unless I knew the phase number.

    If the phase was smaller than 3.141, then the moon was lit from the left, so to speak, and if it was bigger, the moon was lit from the right.

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