3D - 2

What is 4d when referring to moon phases?

I have installed an add on for firefox for moon phases and it says that next full moon will take place on 4d 16th - what does it mean?

Public Comments

1. I have no idea. The next Full Moon is on March 11 02h38m UT, which bears absolutely no resemblance to "4d 16th."
2. I've never seen it written quite that way (4d without a space, unless the "d" is shown as a tiny character, like an exponent to the right of the number 4). It could be the age of the Moon, since that refers directly to the phase. The "age" of the Moon, in its monthly cycle, is often given in days; the count begins at New Moon (day zero). For example, the last New Moon was on Feb. 25 (Universal Time). So that tonight (March 7 in U.T.), the age of the Moon will be 10 days (10 d). This gives a slightly more accurate description of the phase of the Moon than just saying "Waxing Gibbous" (which could apply from day 9 to day 13). In the old days, they used an ordinal counting system (no zero), so that the day of the New Moon would be the "first day". If the weather is fine, most people will notice the crescent Moon as early as the third day (when the age of the Moon is greater than 2.0).