Instead of telescope, how about a planetarium?

As part of an ambitious plan to establish a science museum in Northwest Arkansas, a non-profit group called Supporting STEM and Space Inc. plans to build an astronomical observatory for public viewing sessions. The telescope for this observatory is a 106-year old refractor (using a 24-inch diameter lens as its main focusing element) which the Sproul Observatory at Swarthmore College is only too happy to give away. This telescope, which was de-commissioned 13 years ago, is a dinosaur. Large refractors (this one is the sixth largest ever built) have not been built in a century. All telescopes, from professional to amateur, are now reflectors (using a mirror as the main focusing element), except for the smallest beginner scopes. Refractors require a long tube — the one in question here is 36 feet long — whereas a comparable reflector would need a tube only a few feet long.

The telescope must be housed under a dome that has shutters to open to the sky and can rotate through 360 degrees. Because of the extreme length of the tube, this dome would have to be about 60 to 70 feet in diameter. Swarthmore’s new telescope is a 24-inch reflector, which needs only an 18-foot diameter dome. Moreover, new telescopes have sophisticated electronic controls, so that to view, say, Saturn. you just have to say “Find Saturn” and there it is. And a new reflector telescope would not cost much more than the $20,000 estimated cost of moving the ancient telescope.

Finally, while having an observatory for public viewing would be a nice feature, it is useful only at night, and on clear nights at that. More useful would be a planetarium that could accommodate school groups during the daytime hours.

I strongly support the goal of having a science museum in Northwest Arkansas, but caution the Supporting STEM and Space group from acquiring the Sproul telescope.

MICHAEL LIEBER

Fayetteville Professor of physics, emeritus

University of Arkansas