Shortcut Navigation:
Telling time precisely_HERO

Telling time precisely

Telling time precisely

  • Exhibition Text

    • The discovery of radioactivity in 1896 made it possible to determine the precise ages of rocks. Radioactive elements transform, or decay, into new elements by emission of particles from their nuclei. Because they decay at constant rates, radioactive elements can be used as clocks. For example, the radioactive form of carbon, carbon-14, has a half-life — the time required for half of the carbon atoms to decay into nitrogen — of 5,730 years. Radiocarbon dating is used to establish the age of wood and other organic materials younger than about 50,000 years.

      Show more
  • For Educators

    • Topic: Earth Science

      Subtopic: Geologic Time

      Keywords: Radioactivity, Chemistry, Radiocarbon dating

      Audience: General

American Museum of Natural History

Central Park West at 79th Street
New York, NY 10024-5192
Phone: 212-769-5100

Open daily from 10 am-5:45 pm
except on Thanksgiving and Christmas
Maps and Directions

Enlighten Your Inbox

Stay informed about Museum news and research, events, and more!