A wonderful visualization of tide cycles at the Exploratorium in San Francisco.
Each acrylic slice is a hanging record of tide levels for one day, so you can easily pick out the peak of high tide and the valley of low tide. These peaks and valleys shift from day to day and month to month, as influenced by the moon's gravity (and, to a lesser extent, by the sun's gravity). So the timing of high and low tides reflects cycles in the motion of the moon and sun. The highest and lowest tides occur each month at the time of the new moon and the full moon.
The Exploratorium exhibit, titled "Tidal Ribbon," represents the tidal record for one year (2011), as measured at the NOAA tide station near the Golden Gate Bridge.
Located in the National Gallery of Art's Sculpture Garden, Tony Smith's Moondog is based on a lattice of tetrahedral and octahedral components (15 stretched octahedra and 10 tetrahedra). As described by George Hart, you can think of the structure as part of a diamond crystal lattice, with the smaller tetrahedral faces (visible as equilateral triangles) representing carbon atoms and the remaining "struts" as carbon-carbon bonds.
Ivars Peterson is a freelance writer and editor. He was Director of Publications at the Mathematical Association of America from 2007 to 2014. As an award-winning mathematics writer, he previously worked at Science News for more than 25 years and served as editor of Science News Online and Science News for Kids. His books include The Mathematical Tourist, Islands of Truth, Newton's Clock, and Fragments of Infinity: A Kaleidoscope of Math and Art.