This illustration from the Lunar and Planetary Laboratory shows the approximate sizes of the planets relative to each other. Note that the planets are not shown at appropriate distances from the Sun.

Explore the mythology, structure, observational history, gravitational force, and orbit of Earth's Moon.

Learn some of the characteristics of Mars. These characteristics lead some people to believe that life forms may be found on the fourth planet from the Sun.

Kids learn about astronomy, the study of outer space including the stars, planets, comets, black holes, and the Solar System. History and astronomers in this astronomy for teachers and kids section.

An article explaining how the Greeks were able to use their science and mathematics to predict where astronomical objects such as the Planets could be found in the nighttime sky even though their underlying premise was that the earth did...

This site is astronomy for kids and teachers! Here students can learn about the planet Earth of the Solar System including fun facts, mass, day, year, and distance from the Sun.

This site from the University of Arizona provides a background of Ptolemy's profound influence in the areas of astronomy, geography, and cartography. Includes good pictures and related links.

While astronomers and philosophers have long mused on the possibility of other solar systems, the first planets confirmed to orbit a star other than our Sun weren't found until 1992. The reason it took so long is that it's really hard!...

How do astronomers collect stardust? They design and build satellites that are launched into space to collect particles on specially designed panels. Satellites can be sent to orbit around an object of interest: a planet, moon, or comet....

This site from NASA states Kepler's third law of motion and extends it to develop an equation for the velocity of an orbiting planet.

Simple discussion of plate tectonics and Pangaea. Includes maps and interactives.

Find out why the oceans are blue and what causes waves by clicking here. There is a table of information about the four oceans as well as interesting facts on waves, salinity, and tides.