The SETI Institute
http://www.seti.org/
The SETI League
http://www.setileague.org/
SETI at UC-Berkeley
http://seti.ssl.berkeley.edu/
SETI UNIVERSE
http://www.setiuniverse.com/
The California Planet Survey
http://exoplanets.org/
Other Worlds, Distant Suns Catalog
http://astronautica.com/owds.html
The Extrasolar Planets Encyclopaedia
http://exoplanet.eu/
The Geneva Extrasolar Planet Search Program
http://www.unige.ch/sciences/astro/an/
American Astronomical Society
http://www.aas.org/
Astronomical Society of the Pacific
http://www.astrosociety.org/
Astronomy Magazine
http://www.astronomy.com/
Sky & Telescope Magazine
http://skyandtelescope.com/
Jet Propulsion Laboratory
http://www.jpl.nasa.gov/
NASA
http://www.nasa.gov/
Space Telescope Science Institute
http://www.stsci.edu/
Gemini Observatory
http://www.gemini.edu/
California Academy of Sciences
http://www.calacademy.org/
Downing Planetarium
http://downing-planetarium.org/
Morrison Planetarium
http://www.calacademy.org/academy/exhibits/planetarium/
Lick Observatory
http://ucowww.ucsc.edu/
Very Large Array
http://www.vla.nrao.edu/
Science Photo Library
http://www.sciencephoto.com/
International Association of Astronomical Artists
http://iaaa.org/
SpaceArt.org - Astronomical & Space Artist Hosting
https://spaceart.org/
Imperial Earth - The Space Art of B.E.Johnson
https://imperialearth.com/
Glass Nebula - The Reverse Glass Art of Joy Alyssa Day
https://glassnebula.com/
John Whatmough's Extrasolar Visions
http://www.extrasolar.net/
Mark A. Garlick's Space Art
http://www.space-art.co.uk/
The Space Art of Kevin Davies
http://www.kevindaviesspaceart.com/
Novaspace Galleries
http://www.novaspace.com/
Slawek's Ultimate Guide
http://www.slawcio.com/artsf.html
YAHOO'S Astronomy Listings
http://www.yahoo.com/Science/Astronomy/
Universe Today
http://www.universetoday.com/
Astronomy Picture of the Day
http://antwrp.gsfc.nasa.gov/apod/
Bad Astronomy
http://badastronomy.com/
JACO Aerospace
http://www.e-aircraftsupply.com/space-education/