Image description: This animated GIF shows the dance sequence from Odori Hitori Geiko (Dance Instruction Manual) by Katsushika Hokusai (1760–1849). It’s featured in the exhibition “Hand-Held: Gerhard Pulverer’s Japanese Illustrated Books” at the Smithsonian’s Arthur M. Sackler Gallery.

Learn more about the book and exhibit.

Images from the Freer Gallery of Art and Arthur M. Sackler Gallery.

Read this post in Spanish.

Image description: An animated gif that creates a three dimensional illusion by alternating between two photographs of the White House from the late 19th century.

Did you know that many libraries have 3D images that are over 100 years old? These images are called stereographs. The Library of Congress explains that “stereographs consist of two nearly identical photographs or photomechanical prints, paired to produce the illusion of a single three-dimensional image, usually when viewed through a stereoscope.”

Browse over 8,000 stereographs from the Library of Congress.

Or use the New York Public Library’s Stereogranimator to make your own animated gifs from stereographs.

Image courtesy of the New York Public Library.

From the National Oceanic and Atmospheric Administration (NOAA):

The moon is a major influence on the Earth’s tides, but the sun also generates considerable tidal forces. Solar tides are about half as large as lunar tides and are expressed as a variation of lunar tidal patterns, not as a separate set of tides.

Learn more about the science of tides.