Abstract
This study examined the scientific understanding of astronomical pictures by experts and non-experts. It explored how both groups perceive astronomical images, and their understanding of both what they are seeing and the science that underlies the images. Data comprised n = 8866 responses from a survey linked to the NASA Astronomical Picture of the Day web site and 4 focus groups held at the Harvard-Smithsonian Center for Astrophysics. Results indicated that variations in presentation of color, explanation, and scale affect comprehension of astronomical imagery. With those who are more expert, shorter, more technical explanations are effective; however, scales are still necessary for complete comprehension. Experts tend to look at the images from a more scientific, data-oriented perspective while non-experts are more likely to focus, especially initially, on the aesthetic or emotional values of the images. Results provide suggestions for educational outreach to the public.