Most astronomy neophytes might say the best time is when the moon is at full phase, but that's probably the worst time. When the moon is full, it tends to be dazzlingly bright as well as flat and one-dimensional in appearance.

In contrast, the interval when the moon is at or just past first quarter phase, or at or just before last quarter phase, is when we get the best views of the lunar landscape right along the sunrise-sunset line, or terminator. (The terminator can also be defined as that variable line between the illuminated portion and the part of the moon in shadow.)

Along with the fact that a half moon offers more viewing comfort to the eye than a full moon does, using a telescope with just small optical power (magnifications of 20- to 40-power) or even good binoculars allows us to see a wealth of detail on the surface. Around those times when the moon is half-lit or in its gibbous phase, those features lying close to the terminator stand out in sharp, clear relief. [Photos: Full Moon Captivates Skywatchers in February 2012]

Next chance

The moon next arrives at first quarter phase on Leap Day: Wednesday (Feb. 29) at 8:21 p.m. EST. That will be the moment when its disk is exactly 50 percent illuminated. Lunar mountains will be visible as the sun lights them from the right.

How does the moon's brightness compare now with full phase? Most would probably think it's half as bright, but in reality astronomers tell us that the first quarter moon is only one-eleventh as bright as full. This is due to the fact that a half moon is heavily shadowed, even on its illuminated half. And believe it or not, it isn't until just 2.4 days before full that the moon actually becomes half as bright as full.

In contrast to a half moon, a full moon is almost completely illuminated, especially right around its center, where the sun shines straight down into all the microscopic crevices. Except for perhaps around the moon's immediate edges, you will find no shadows at all.