A Question and Answer Guide to AstronomyWritten by Carol Christian & Jean Rene Roy, 358 pages, paperback, 2nd Edition Are we alone in the Universe? Was there anything before the Big Bang? Are there other universes? What makes stars shine? Where does Earth's water come from? Why is the night sky dark? Was there ever life on Mars? How do telescopes work? This engaging guide book answers all these questions and hundreds more, making it a practical reference for anyone who has ever wondered

25" HD Optical Tube Assembly

Focal Length of Eyepiece 2 (mm): 10 mm (0

25 and 31mm Filters is certainly one of the smallest 5-position filter wheels in the world

These tube assemblies are equipped with the same dovetail mounting bar used on the CGE and Advanced Series for easy attachment to a variety of popular mounts

Tracking Rate: Lunar

Advanced VX 9

All these different anti-reflection coatings on each lens surface have then been optimized to be most effective where the human eye has its highest sensitivity at night - at about 520 nm - in the green region of the spectrum

Clear aperture: 60 mm clear aperture lens optimized for a 42 mm image circle for use with large CCD sensors

it reduces exposure time by a factor of 3

The exciting new lightweight and highly portable Sky-Watcher AZ-GTiX Dual Saddle Alt-Azimuth Mount

Plastic spiral binding lets star charts lay flat

so you can focus on astronomy