Telescope, Transit of Venus

This object is not part of the Cooper Hewitt's permanent collection. It was able to spend time at the museum on loan from National Museum of American History as part of Tools: Extending Our Reach.

In the eighteenth and nineteenth centuries, ascertaining the solar system’s size was seemingly impossible. Relative distance of each planet from the Sun was known, but not actual distance. The most promising solution involved measuring the "Transit of Venus"—the passage of the planet Venus across the Sun’s face. Plans called for observers at two different points to register the time transit began. The two would therefore record slightly different times. In theory, knowing that time difference and distance between locations would make it possible to calculate distance to the Sun. However, these measurements were almost impossible to make. In 1874 the U.S. government sent eight expeditions to observe the transit, stationing them across the globe with identical equipment, including eight of these telescopes, made by the American telescope maker Alvan Clark. Although not completely successful, the expeditions were a bold assertion that American science and scientific-instrument making had come of age.

This object was previously on display as a part of the exhibition Tools: Extending Our Reach.