 Two great nights with the Moon and planets. We've had some wonderfully clear, autumnal nights over the past week, with Jupiter and Saturn riding high in the evening sky and the Moon waxing and waning nearby. I'm teaching what may be my favorite course at the moment - about the human history of nearby celestial bodies (what I call "neighboring worlds"), and a special highlight is taking my students out for a night with a telescope. I have now accumulated some very fine refractors, however, and I worried about how they'd fare after being handled by twenty students. To that end, I drew on my research funds to buy a William Optics Zenithstar 81. It's a beautiful little refractor, and I figured that it would be more than adequate to give my students an impressive view of the Moon. For their first assignment, they need to find a feature on the Moon and then write a history of how people have understood, imagined, explored, or planned to exploit that feature.  William Optics certainly makes some beautiful telescopes. A few things immediately struck me about the Zenithstar. First, it costs about a third as much as the TeleVue 85 I used to own - less than a third, when you consider it comes with its own mounting rings, dovetail, Bahtinov mask, and carrying case - despite giving up only four millimeters in aperture. Second, its build quality looks to be on par with the very best telescopes I own and have owned, with the possible exception of my TEC 140. Third, it seems to weigh less than the FS-60Q I once owned, and much less than the TV 85, and its sliding dew shield makes it much more compact than either telescope. It was really easy to carry the telescope to a darker corner of campus, and there set it up on my DM-4 mount and Berlebach Report tripod. Almost immediately, the Plossl eyepieces I'd decided to use provided beautifully crisp views of the nearly fully illuminated Moon. The students who had started to gather were predictably impressed. When we found we had a few minutes to spare at the end of the evening, I decided to try showing them Jupiter and Saturn. At about 56x, the planets were small, but beautifully sharp and clear. Many of my students were awestruck; they had a hard time believing that they could really see the major cloud belts of Jupiter and the rings of Saturn from downtown DC.  A magical evening near the Potomac. Experiential learning is always special; it makes the otherwise abstract concepts we discuss in class come alive for my students, and it can provide lifelong memories. I for one was stunned by the performance of the little refractor. It is, by far, the most portable telescope I've owned, and when it comes to performance it really doesn't give up much to the TV 85. I loved my TV 85, but I would have a hard time recommending that telescope as a go-to instrument when the Zenithstar seems to provide so much more value for the cost.  It's quite a place to set up. Last night conditions were even better, and now I resolved to head out with my biggest telescope: the TEC 140. The weight of the telescope, tripod, and mount means that I really can't haul everything to my favorite field. I targeted the little alcove next to a church that I've used over the past year, yet when I arrived as I was dismayed to find that the church had installed a new streetlight that completely ruled out observing there. I wandered about, dragging my heavy gear, until I decided to head down to a little amphitheater near the National Cathedral. There I found a perch that, if I moved around a bit, afforded me a view of Jupiter, Saturn, and the Moon through the canopies of nearby trees.  It's a goofy picture, but still: it proves I was there, with the TEC. When I swung the TEC to Saturn, I was mesmerized. This was only the second time I'd used the TEC, and the first time in good seeing. In those conditions, Saturn looked absolutely stunning, like a beautiful jewel set in a velvet background. Its many moons were brilliant and sharp, and the shadow of the planet on its rings gave me the rare sense that I was actually seeing a world in three dimensions (often, objects in the eyepiece look flat, and therefore two dimensional). Cloud details were obvious on the planet's yellow-white disk. Switching over to Jupiter provided an even more spectacular revelation. The TEC provided what may have been my best-ever view of the planet, with more cloud belts and zones than I could count, delicate, feathery structures within those belts and zones, and a perfectly obvious, brown "barge" - an elongated, oval cloud feature - near the planet's equator. There was a contrast and vibrance to the planet's colors that you just don't get with a smaller refractor, and all four Galilean moons were visible as clear disks, rather than points of light. Jupiter and Saturn soon wheeled behind the trees, so it was time for the waning gibbous Moon. Once again, I was dumbstruck. The Moon wasn't that far above the horizon, but at 163x there was just such a wealth of subtle, perfectly sharp detail, from jumbled crater peaks to winding rilles and delicate scarps. The terminator was perfectly positioned to throw mountain after mountain in sharp relief, and in exploring them I eventually lost track of time. Then a giant cricket jumped on my pants, I realized in shaking it off that it was past midnight, and I began packing up for the painful trek home.
The TEC 140, I have to say, is noticeably better than the APM 140 I've also raved about in these pages. I'm not sure it's worth the extra cost; certainly I could never have afforded the difference if I didn't use the telescope for my research and writing (which means I could draw from my research funds to buy it). I realize how lucky I am, and I hope I can keep using the telescope for a lifetime. It won't be that often, however, until I manage to own a backyard; as wonderful as the telescope may be, it's also hard to transport more than a few minutes from our home.
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