Use Credo Reference to search across 422 reference books including dictionaries, encyclopedias, and subject-specific resources.

Full-text access to dozens of encyclopedias in all subject areas.

Be sure to use this link for an ad-free, full content experience!

Use succinct search terms. For example, "black holes" - NOT "how big is a black hole?"

Here you CAN search for a phrase. Be strategic, though!

Contains articles from hundreds of magazines and reference books.

Contains newspaper articles from the U.S. and around the world. Put multi-word search terms in quotes to get better results!

Searches magazine and journal articles from thousands of periodicals. Draws on more scholarly sources than MAS Ultra.

SweetSearch is a Google-powered custom search engine that only searches 35,000 Web sites that a staff of research experts deems credible. Be sure to put quotes around your search terms!

This site is intended for students age 14 and up, and for anyone interested in learning about our universe.

HubbleSite is produced by the Space Telescope Science Institute's Office of Public Outreach. The site is used to to share Hubble's remarkable discoveries with the public.