Comets:
Definition by Wikipedia The Age of Comets
Catching a Comet Death on Camera Comet Death Observed for First Time (July, 2011)
Comet Lovejoy Plunges into the Sun and Survives
Evidence that comets could have seeded life on Earth
Asteroids:
Definition by Wikipedia After Chelyabinsk: European experts assess asteroid options
Asteroids: The New 'It Mission' for Space Exploration NASA survey counts potentially hazardous asteroids
List of Potentially Hazardous Asteroids (PHAs) NASA/JPL's Near Earth Object Program Busting Armageddon
Identification of origin of particles brought back by Hayabusa NASA scientist figures way to weigh space rock
Asteroid nudged by sunlight: most precise measurement of Yarkovsky Effect
Asteroid Served Up "Custom Orders" of Life's Ingredients Trojan Asteroid Shares Orbit with Earth
Asteroid 2011 AGS: a reality check Small asteroid to whiz past Earth safely
Stanford professor wants to find asteroids that threaten Earth
NASA Telescope finds fewer Asteroids Near Earth Explained: Near-miss asteroids
Rosetta flyby uncovers the complex history of asteroid Lutetia
NASA's NEOWISE Completes Scan for Asteroids and Comets Fireballs that Produce Meteorites
Soar Over Asteroid Vesta in 3-D NASA's Swift Observatory Catches Asteroid Flyby
New NASA Dawn Visuals Show Vesta's 'Color Palette' Is Vesta the "Smallest Terrestrial Planet?"
Dawn sees new surface features on giant asteroid Vesta in Dawn's rear view mirror
Experimental evidence that an asteroid impact led to the extinction of many species 65 million years ago
Near Earth Object media/risk communications working group report
Villain in disguise: Jupiter's role in impacts on Earth Nukes to save the Earth
Defending planet Earth: Near-Earth object surveys and hazard mitigation strategies
Engineers set their sights on asteroid deflection Near Earth Asteroids
UCLA space scientists find ways to monitor elusive collisions in space
Meteorites:
Definition by Wikipedia
Meteorites: toolkits for creating life on Earth Meteorite from Mars fell in Morocco: scientists
Meteorites reveal warm water existed on Mars Studying meteorites may reveal Mars' secrets of life
NASA Ames helps search for and study of Sutter's Mill meteorites
Rare meteorites created in violent celestial collision Russian meteor million of years old
Discovery of probably Tunguska meteorites at the bottom of Khushmo river's shoal