Last week, in a blog post titled "Astronomy 101" I discussed the visual marvels available to boaters who watch the night sky with only the naked eye.

But as you begin to master stargazing, you'll likely want to know a little more about what you're seeing. When that happens, there's some gear that you should consider acquiring to make the experience even more satisfying.

Start with a red flashlight with adjustable brightness. Once you've got your night vision, you don't want to ruin it using a bright white light to glance at your star chart (or to find your drink, for that matter).

My favorite all-purpose flashlight is the little white-LED Petzl Tactikka Plus headlamp with a red flip-up filter and three brightness settings. A set of AAAs seems to power it forever, and the red filter and adjustable intensity make it useful for all kinds of tasks around the boat or house. In fact, since I moved mine to the boat, I really missed it at home, so I bought a second one.

PETZLA favored flashlight is the little white-LED Petzl Tactikka Plus. You'll need a pair of good-quality 7×50 binoculars. The reason I recommend 7×50s is that many cruisers already have a pair. The qualities that make this size so useful aboard a boat are precisely the same qualities that make them a good choice for astronomical work: they offer a wide field of view so that you can find what you're looking for and keep it in sight. They also have reasonably large objective lenses, which gather a lot of light, allowing you to see more astronomical targets. They're also not too heavy, so you can use them long enough to really see what there is to see. Finally, despite what you might think, 7x magnification is enough to provide enormously enhanced views, compared to the naked eye.

BINOCULARS AND CHARTS

I'm extremely pleased by my twelve-year-old Fujinon Mariners. They're lightweight, plastic-bodied, fairly rugged and contain good optics, particularly for the price. Fujinon makes a more expensive metal-bodied binocular called the Polaris, but if I've got a $700 pair of binoculars, all of a sudden I'll feel like I have to be extra careful with them. The Mariners are about $200, and if I accidentally damage or lose them, it's OK – not great, but OK. Because of this, I use them. I take them on trips when there is risk of theft. I allow the kids to use them. Here's an old astronomy adage: "What's the best telescope? The one you have with you." My beloved Fujinon Mariners have a permanent spot aboard the boat.

FUJINONThe Fujinon Mariners are lightweight, plastic-bodied binoculars. Of course you need a star chart, or something similar. You wouldn't go cruising without the proper charts, right? While it's OK to stargaze without a chart, sooner or later you'll probably want one. There are lots of options, from free to very expensive. I suggest the free option, to start with: Heavens Above is a great site. You can generate star charts for any location, for any date/time. You can generate a table of "fly-by" opportunities to view the International Space Station or the Space Shuttle, for any location. Here's a view that helped me spot an ISS pass over Seattle on May 24. It rose in Gemini and passed near Saturn, fairly high in the southwestern sky.

Honestly, free online star charts are so useful that it's difficult to recommend anything else, unless you don't have access to the internet. In that case, consider printing out some star charts ahead of time for the locations and dates you'll be cruising. Just choose a time about an hour after sunset, when you're most likely to be outside. If you're an early riser, generate charts for an hour prior to sunrise. For the basic stars and planets, you won't need to generate separate charts for every single day. A single chart will help you identify what you can see for about a week. For fast-moving objects such as comets, it's best to have a chart for every evening or morning you're likely to be out observing. Artificial satellites pass overhead so quickly that you need a chart for that specific time.

This view helped me spot an ISS pass over Seattle on May 24 as it rose in Gemini and passed near Saturn.

If you just want to start learning the names of the stars and constellations, and you don't think you'll remember to print out online star charts before your trip, consider one of those round plastic star charts that you rotate to index the date and time (these are called "planispheres"). If you've got a Blackberry, Palm, Pocket PC or Smart Phone, you can find inexpensive applications that generate tiny but usable star charts on the fly.

Get a tutorial of some kind. Although there are plenty of wonderful books for beginning astronomers, I'm fond of Tom Trusock's "Small Wonders" series at Cloudy Nights. Each of the 30 or so articles takes you on a tour of a specific area of the night sky. The articles start with easy targets you should be able to spot with the naked eye, and then move on to more difficult targets that require binoculars or a telescope to find. They're northern-hemisphere-centric, and you need to select an article you can actually use during the time of year you're observing.

Trusock wrote the first set of Small Wonders articles about once a month, and they tended to focus on whatever constellation would be directly overhead during the hour or two after sunset that month, when most observers would be out viewing. Now that these articles are archives, you might have to do your own homework to figure out which article is most appropriate for your next voyage.

ADVANCED EQUIPMENT

These simple, inexpensive tools ought to get you started, and could keep you occupied for years. While you might think that all the "real" astronomy buffs own enormous telescopes, many experienced observers actually spend the majority of their time behind a pair of binoculars; they like the convenience, the like using both eyes, and they're able to see what they want to see.

But if you get hooked on stargazing, you'll eventually want to see more, and you might get to the point where you're willing to spend a little cash to accomplish this. You want to optimize the utility and value of any astronomy gear you take cruising, and so far, that's been easy: the binoculars serve a valuable marine/terrestrial role aboard, and none of the other items cost much or take up much space. But if that's going to change, you'll want to give it some thought.

Due to space constraints aboard a boat, we almost never carry any accessory that only serves one purpose. We also avoid bulky gear, and gear that is fragile or easily damaged by moisture. With regard to astronomy, where does that leave us? In my opinion, the first item to consider is a tripod, and the second is a telescope.

TRIPOD AND TELESCOPE

While ashore (or aboard, I suppose, if your boat is extremely stable), you'll appreciate a tripod with a sturdy binocular mount. While you can see a lot just holding those 7×50s up to your eyes, you can see even more if they're not wobbling around. Even while holding them, just using some stable object such as a tree or a picnic table to steady them can reveal, for instance, the four "Galilean moons" orbiting Jupiter. Mount them on a tripod, though, and you'll have no doubt about what you're seeing. The Galilean moons will be obvious. The Pleiades star cluster will resolve into more than 20 individual stars, not just the seven or so you can see with the naked eye.

I use a photographic tripod from Bogen-Manfrotto (model 3401B), with a fluid-motion video head on top (model 3130). This is pretty stable for a pair of 7×50 binoculars, and the fluid head allows you to pan and tilt smoothly, which is important when you're navigating from one astronomical target to another. It also makes spotting ships, birds, and aircraft a lot more fun, since you can track moving objects and keep them in view. You can't do that with the typical still-camera mount on most photography tripods; the fluid motion of the video head is critical.

If you really get into it, you might consider a telescope. You can learn more than you'll ever want to know about amateur astronomy by browsing the forums at Cloudy Nights. I encourage you to spend some time over there, if you're at all interested in astronomy.

ZEISSThe Zeiss Diascope mounted on a tripod. But here's my heartfelt advice: for cruising, get a high-end "terrestrial" spotting scope, not an astronomy scope. The brand names you'll consistently find at the top of the heap are Leica, Swarovski, and Zeiss. This isn't to say that other manufacturers, including Nikon, Kowa, and Fujinon, don't make great spotting scopes, by any means.

I own an 85mm Zeiss Diascope with the variable-magnification eyepiece, and it's absolutely wonderful. Spotting scopes, designed primarily for bird-watchers, are lightweight, compact, durable, and waterproof – precisely the features we look for in cruising gear. Also, they display an erect image, not an upside-down and reversed image as dedicated astronomy scopes do. For myself, I want a telescope I can use for informal astronomical work and for terrestrial spotting. The erecting prism degrades the image a little, which is why astronomy purists will steer you away from them. Ignore that advice, for the time being. If you jump into astronomy with both feet, you'll form your own opinions about what you want anyway.

SPOTTING SCOPE

To be fair, my little spotting scope does not produce the expansive, full-color views you see on the cover of National Geographic magazine. To give you an idea what you might see through a top-quality spotting scope, here's an image of Jupiter that is very similar to views I see through my Zeiss through light-polluted Seattle skies.

As in this image, I see a disc, not merely a point of light. The disc has two major dark bands across it, corresponding more or less to the latitude of our own tropic lines on Earth. Saturn resolves as a ringed disk, but no color variations are visible on the face of the planet or the rings.

Here's an image of Jupiter that is very similar to views I see through my Zeiss through light-polluted Seattle skies.I own two telescopes: The Zeiss and a nine-inch Dobsonian reflector, which is about four feet long. All things being equal, a bigger telescope is better. Views of Saturn through my big telescope are very slightly better than with the Zeiss: I can see the Cassini Division in Saturn's rings, for instance, and slight variations in the surface of Mars. However, the fact is that I almost never use the bigger telescope: I find it too cumbersome to haul outside, I don't enjoy fiddling with the eyepieces, and it's much more difficult for my children to use. The Zeiss is dead simple: Adjust the tripod to a good height, point the telescope where you want it by sighting along the tube, look through it on lowest magnification and find your target, and adjust zoom and focus until you're seeing as much as you can.

MONFROTTOFor astronomical use, I change to a Manfrotto 410 geared head, which allows for very fine adjustments. I use the same tripod with both my binoculars and my spotting scope, but for astronomical use, I change to a Manfrotto 410 geared head, which allows for very fine adjustments in two axes. I'll be honest: this tripod, even with the geared head, is just barely adequate for the spotting scope. It's a bit wobbly at 20x magnification, and you really can't touch the tripod or telescope at all when zoomed in at 60x. Get it pointed in the right direction, remove your hand, make a focus adjustment, remove your hand, re-center the image (which is drifting out of view as the earth rotates), remove your hand. This photographic tripod is the weak link in my portable astronomy kit, right now. If I were to spend more on gear, my next purchase would be a dedicated astronomy tripod with a motorized equatorial mount that keeps the telescope pointed in the same direction while the earth rotates beneath it.

Dedicated amateur astronomers may scoff at this discussion of "advanced gear," which is really pretty basic. If you want more, I suggest you head over to Cloudy Nights. I'll remind those astronomy über-geeks that I'm writing for a crowd that, like myself, might best be described as "incidental astronomers." We're not out there to do astronomy, we're out there cruising on our boats. Once in a while, we'll glance up and realize that it's a lovely, still, clear night, and we'll go grab the binoculars and have a look.

So good luck with your astronomical adventures. In case you haven't watched The Thing From Another World recently, I'll leave you with this: "Watch the skies, everywhere! Keep looking. Keep watching the skies!"