Design

 Techniques and Strategies to Imitate the Moon

1.The Color of the Moon

Sunlight is a mixture of colors that produce what we perceive to be white light. If you bounce sunlight off a reflective white surface, the reflected light will be identical in color to the sunlight. If you bounce sunlight off the surface of a red balloon, the balloon will absorb all colors except red – only red light hits your eye and the balloon appears red.

It turns out that the moon absorbs twice as much violet as it does red. For this reason, the moon is slightly reddish. A full moon when it appears directly overhead has a color temperature of about 4,150°K. Compared to incandescent lighting (around 3,000°K), moonlight is slightly blue but not nearly as blue as a bright sunny day (as much as 10,000°K)

Even though the moon is more red than blue, common belief tells us otherwise. There are songs about the blue moon and filmmakers use blue filters to simulate the moon.

2.Heights and Angles

To simulate the light of the moon, we mount fixtures as close to the moon as we can (just kidding). Ideally, we mount fixtures at least 25 ft. high and project the light through lower branches. This illuminates the ground with the kind of dappled light that suggests the moon.

The ideal mounting height is set to minimize potential direct glare while attaining the maximum area of illumination. Direct glare results when light from the bare lamp enters an observer’s pupil at a low-enough angle so the bright light projects onto the retina. This angle is estimated to be about 45 degrees (halfway between horizontal and vertical).

3.Conclusions

Moonlight evokes certain positive feelings and impressions that we strive to imitate in our landscape lighting designs. But it is not that we try to exactly match the moon’s color or brightness. Rather, we set our own rules for placement and projection based on plans that satisfy the various goals of the lighting design.