This site, created by the National Aeronautics and Space Administration, offers user-friendly, continuously-updated access to approximately 2,000 images from various solar system exploration programs. Users can select...

Authored and curated by David P. Stern, this is a lesson plan for teaching Newton's formulation of gravity. It is linked to textual reference materials about the theory and history of gravity. The motion of astronomical...

This website from NASA is a photo gallery that contains images of planets, nebulae, galaxies, globular clusters, stars, compact objects, and spacecraft.

This Photojournal from NASA provides the first image of Earth captured from the outer solar system since Voyager 1 went to Neptune. In a magnified view, the moon is seen as a small protrusion. The article provides...

This exercise has students use a simple physical model of the Earth, sun, and moon to understand why the moon changes phases from the perspective of Earthly observers. Students hold up balls representing the moon in a...