Home > Math Lint Archive Detail

<< Prev 11/4/2012 Next >>

Loony Lunar Fractions Where 1/2 is 1/4

One is never too old to learn things, or is correct past learnings.

For example, when you hear the term "half-Moon," what do you think of? Or see?

Is this the "half-Moon"?....No, it actually is the "quarter-Moon"?

I just learned (i.e. relearned or unlearned) that the key is not "seeing" a half of the Moon. That is the wrong mathematics or geometry...and it gets quite confusing.

Lunar fractions do not refer to geometric view of the Moon. Rather, the reference is the fraction of the orbiting cycle of the Moon.

Expert Alan MacRobert, editor for Sky & Telescope, writes: "The Moon is half lit when it is a quarter of the way around its orbit. ... The Moon is full when it is halfway around the sky...."

Does this make sense...yes and no! Regardless, when I see a "half-Moon" I will still not think "one-quarter"!

Source: Adapted from D. Feldman's A World of Imponderables, 1992, p. 646