The MESSENGER orbiter's January 2008 flyby of the planet Mercury was historic. The last time a spacecraft visited was 1975, and it only mapped half the planet. MESSENGER is now sending back a complete picture of Mercury, shedding light on its geological history. But the ongoing mission will return much more than images. Its data on the planet's core, magnetic field, composition, and other attributes will help scientists answer pressing questions about the evolution of the terrestrial planets and even the Solar System itself. In the feature video, watch the MESSENGER science team react as the orbiter's first images of Mercury roll in. To explore the images in detail, click on the slide show at left. Find out more on the mission by clicking on the essay "First Planet Finishes Last."
How much can you reduce your carbon dioxide emissions? Is it worth it? Learn how simple choices multiplied by everyone in your community can make a big difference.
Bolivia’s diversity of animal and plant life is among the greatest in the world. Learn why the country has designated more than 17 percent of its land as protected areas.
Follow mermaids around the world and throughout history to see first-hand how cultures share and reinterpret mythic creatures.
The elusive giant squid was first described 500 years ago by Scandinavian sailors. Investigate what we've learned--and what still remains unknown--about this mysterious deep-ocean creature.
Continue tracking mythic creatures through the art they've inspired and the science they've helped shape with this collection of related Web sites.
After having students conduct a simple solar energy experiment, challenge them to build a better water heater with this classroom competition.
Explore your ancestral past and the 22nd-century possibilities of DNA research with this collection of kid-friendly titles selected for the Hall of Human Origins.