The 12-inch gold-plated records contain greetings in 59 languages, samples of music from different cultures and eras, and natural and human-made sounds from Earth. One record is currently 16.89 billion km from Earth, the other is over 13 billion km away. NASA Center: Jet Propulsion Laboratory hide caption

itoggle caption NASA Center: Jet Propulsion Laboratory

In this illustration, new viruses emerge from an infected human throat cell. When you get the flu, viruses turn your cells into tiny virus factories that help spread the disease. Courtesy XVIVO/Zirus hide caption

itoggle caption Courtesy XVIVO/Zirus