This is the best site to spend hours and hours on. Be sure to click on things you want to learn more about and turn on the sound. Enjoy.
http://htwins.net/scale2/
This is the best place to get stunning, vivd images from the Hubble Telescope, Kepler Telescope, and to track comets, asteroids, and what's going on here on Earth.
http://apod.nasa.gov/apod/
http://apod.nasa.gov/apod/
Hands down, one of the best TV shows. This site offers full length episodes plus interviews with scientists from all fields.http://www.pbs.org/wgbh/nova/
If I could talk to one person everyday for the rest of my life, it would probably be this guy, Dr. Neil DeGrasse Tyson. Astro Physicist, brilliant scientist and a very funny man. See for yourself on his videos. He makes learning science fun and engaging.
http://www.haydenplanetarium.org/tyson/
Possibly one of the most comprehensive science shows available. This is on the radio and each show offers a wide range of topics from renewable energy to fractals.
http://sciencefriday.com/