The Bronx Blogger

Thursday, August 25, 2005

The moon and Mars

I just got back from the roof with my son.

Earlier this evening we were at the Costco store in Yonkers where we noticed a new shipment of telescopes, the Meade DS-2090-AT-TC Refracting Telescope. The telescope comes equipped with a 90mm lens, an Autostar computer-guided slewing motor, a 26mm and a 9.7mm eyepiece, a light but sturdy aluminum tripod, and several other odds and ends.

The price for the telescope is $199. Since the Autostar control device is worth about $80 or $100 just by itself, $100 or $120 seemed like a very good price for a 90mm refractor, and I decided to buy it. And since Costco has an excellent return policy, there was no risk of wasting money by making the purchase.

Once back at home, I assembled the telescope. Telescope assembly was pretty straightforward, except that the instructions provided were more confusing then they had to be. My son and I took the elevator to the top floor of our building and carried the scope up to the roof.

It is clear out, but a little hazy, with a three-quarters waning moon, and Mars shone brightly only a few degrees or so from the moon. I tried to get the moon in position, but for some reason it just wouldn't focus. I was just getting a featureless white smudgy blur.

After fifteen minutes of frustration, I tried switching from the 26mm eyepiece to the 9.7mm eyepiece, but that didn't help. And then I noticed that the eyepieces weren't even staying in place properly. It turned out the 26mm had unscrewed into two pieces, with the silvery metal end lodged in the eyepiece slot. When I reassembled the eyepiece, I trained the telescope on the moon, and there it was! With a little bit of focusing, it looked clear as a bell (with a thin false orange band around the perimeter). The 26mm eyepiece, combined with the optical tube's 880mm focal length, yielded a 34x magnification, which meant the moon looked as if were looming only 7,000 miles away, with mares, mountains, craters in plain view, and the long shadows along the sunset twilight line adding dramatic depth to everything. My son was thrilled and delighted. He was actually pretty pleased just to have seen the bright white smudge before, so seeing a real live sharp image was very special indeed.

The scope has a small red-dot finder mounted on the optical tube. I used the moon to align the finder properly, and used the finder to get the telescope to point at Mars. There were a few faint stars in the field of vision which provided a nice pinpoint contrast to the small but perceptible disk of Mars.

When I switched to the 9.7mm eyepiece in order to get the 91x magnification, the image quality was actually worse. Mars was bigger, but more wobbly and distorted, due to poor weather conditions for viewing.

But when I used 91x enlargement on the moon, the view was great. The moon was hanging out only 2600 miles away! We could move the telescope over the surface of the moon as if we were standing in front of a large window and turning to look this way and that. My son was very impressed with that, even though he was now tired enough to want to call it a night. Perhaps he'll have dreams of touring the solar system tonight.

[The 9.7mm eyepiece view of the moon didn't have the band of false orange color, but it did have a very slender, faint band of purple instead.]

Some of you out there have probably heard that Mars is very close to the earth right now, closed than it has been in hundreds of years. So if you want to take advantage of that, the Meade refracting telescope at Costco seems to be a quick and easy way to go for it. I didn't use the Autostar computer-guided thingie tonight, but I'm looking forward to it. They've upgraded the catalogue of trackable celestial objects from an old total of 1,400 objects to a new total of 30,000 objects.