Google Sky is a fascinating resource to explore. Just start scrolling in or out and you will be amazed at the details. It's like you have access to all the worlds best telescopes at one time. The simulation includes constellations and distant galaxies.
This website is a massive collection of Simulations and resources for almost every science topic. There is an almost overwhelming amount to browse through and explore.
" SimBucket has created a large number of original HTML5 physics, chemistry, and biology simulations. This curated group contains some of the most popular simulations from www.simbucket.com. "