Piano notes made visible for the first time
Shannon Novak, a New Zealand-born fine artist, commissioned us to image 12 piano notes as inspiration for a series of 12 musical canvases. We decided to image the notes in video mode because when we observed the ‘A1’ note we discovered, surprisingly, that the energy envelope changes over time as the string’s harmonics mix in the piano’s wooden bridge. Instead of the envelope being fairly stable, as we had imagined, the harmonics actually cause the CymaGlyphs to be wonderfully dynamic. Our ears can easily detect the changes in the harmonics and the CymaScope now reveals them—probably a first in acoustic physics.
Capturing the dynamics was only possible with HD video but taming the dynamics of the piano’s first strike, followed by the short plateau and long decay phase, was tricky. We achieved the result with the help of a professional audio compressor operating in real time.
En el enlace a la noticia hay una animación flash donde puedes tocar cada nota viendo el desarrollo que produce.
Why can we see the Moon during the day?
Our natural satellite the Moon takes 27.3 days to orbit the Earth, and we only ever see one side of it because it’s tidally locked, meaning that for every orbit, it spins on its own axis exactly once. But the Moon is not luminous in its own right—we can only see it due to sunlight reflecting off its dusty surface: the side of the Moon facing the sun is fully illuminated, while the other half is in shadow. Because the Moon is constantly moving, sunlight hits it at different angles each day, and these changing angles create the lunar phases we see on Earth. A new moon occurs when the Moon slides between the Earth and sun, so the sun illuminates the side facing away from us and casts our side into shadow. A full moon is the opposite—the Moon, sun and Earth are in approximate alignment again except this time Earth is between the other two, so sunlight hits the side of the Moon facing us. Since the Moon’s orbit is about 5 degrees off the Earth-sun orbital plane, the Earth doesn’t block the sunlight. All the other phases are gradual transitions between, since from our perspective on Earth we can see both the part of the Moon in sunlight and the part in shadow. But the Moon is not exclusively a creature of the night—in the weeks before and after the new moon, the Moon is on the sunward side of Earth. This means it can be seen in the sky at the same time as the sun, i.e., in daylight hours. After all, it’s just another object in the sky lit by the sun.
(Image Credit: Southern Skies, Dr Doug Welch, 2008)