Astrobiology Primer

Astrobiology: The Study of the Living Universe (Chyba & Hand)

Astrobiology at NASA

NASA's Astrobiology Roadmap

NASA Astrobiology Graphic Novels

Recorded talks from NASA Astrobiology Science Conference 2012

Habitability of Our Earth and Other Earths

NASA's Mars Program

NASA's Martian MeteoritesPage

The Mars Society

The USGS's Astrogeology Program

Extrasolar Planet Interactive Intro

California & Carnegie Planet Search

An Extrasolar Planet Encyclopaedia

NASA Exoplanet Archive

Kepler Spacecraft's search for Earth-Size Planets

Seager Perimeter talk: "Exoplanets and the Search for Habitable Worlds"

Astrobio Conference talk

The SETI Institute

SETI at Harvard

Columbus Optical SETI Program

SETI at Berkeley

Big Ear Radio Observatory

Delano TEDx talk: "Is Anyone Out There?"

The Sagan-Mayr Debate (1995)

Here's an Asteroid Impact Calculator.

Here's the JPL NEO site.

Beware of Potentially Hazardous Asteroids!

NASA's Comet and Asteroid Impact Hazard site.