This site explains what tides are and the difference between Proxigean Spring Tides, spring tides, and neap tides, and how these are formed. Graphic illustrations are provided.

This FYI for Kids (Volume 5, Issue 3) focuses on the tides. It explains the pull on the earth by the sun and moon and how the tides go in and out.

In this online textbook produced by the Smithsonian, students explore the phases of the moon, the moon's orbit, the origin of the moon, and the tides. Includes numerous inquiry-based activities.

Provides a brief overview of Ariel, one of Uranus's moons. Details how its deep valleys were formed. A NASA astronomy picture of the day.

Even great scientists make mistakes! This illustrated essay from the NOVA Web site looks at Galileo's theory of the tides, which, while well thought out, was wrong.