For the past 400 years, astronomers have explored the universe with telescopes. Telescopes gather light from distant objects and funnel the light into our eyes, or into a camera. But, Earth’s atmosphere absorbs some of the light coming from those distant objects. Space telescopes, positioned above the atmosphere, have become extremely valuable tools for exploration, and the Hubble Space Telescope is arguably at the top of the list.

This Reading provides background information on the underlying concepts in the Activities included in the book, Project Earth Science: Astronomy, Revised 2nd Edition. The Readings go beyond what is found in the background information in the Activities. They can be used as supplementary information for the teacher, or to enhance classroom discussions.