First, a reminder: The biggest full moon since 1993 rises Friday evening at 4:13 or so. It will stand highest up around midnight, but will appear largest just when it's coming up. It'll be well worth a look. For more details, and Hudson tide information, see last week's Night Sky. Saturday night the moon will be nearly as big and almost as full, and will rise just before 5:30 p.m.

The sky has been eventful lately. Our conjunction-watching night at Mohonk Mountain House brought a nice crowd, and I know that many people saw the get-together of Moon, Jupiter and Venus throughout our area. I apologize to readers here for not getting it into this newspaper in time. No excuse; I'd been planning for it for two years, and did feature it in the Old Farmer's Almanac, on Public Radio and in Astronomy magazine.

I noticed that some exuberant media sources were calling it "once in a lifetime" or "once every 60 years," and that's just silly. The December 1 event was indeed 2008's best conjunction; but almost every year brings a great one, and we'll have an even-better event on February 27, just ten weeks from now.

Four ingredients go into creating a truly memorable conjunction. The first is simply the brightness of the participants. The second is the number of objects that come together. The third is how closely they meet: The greater the spacing, the less eye-catching it appears. The final factor is the altitude. Does it happen so low that horizon haze or bright twilight diminishes its impact, or even limits its very visibility? To my mind, the conjunction is newsworthy when a fifth condition is met as well: It must happen in the convenient evening hours, not in the pre-dawn sky at 4 or 5 a.m.

The great conjunction this February 27 excels at four of the five conditions: The Moon meets Venus when the Evening Star has reached maximum brilliance. At magnitude -4.8, Venus will be scorching. Next, the two will sit very close to each other. Finally, they'll be higher up than this recent December conjunction.

That will be 2009's only superb conjunction. The following year offers only one as well: on August 12, 2010, when the Moon meets Venus, Mars and Saturn all at once. The following year hasn't a single worthy conjunction. But 2012 offers four fabulous events, and 2013 has two. We'll get none in 2014 and three in 2015.

A bright but somewhat large triangle like we had the other week is quite striking, but the other frequent excellent conjunction of a dazzling star closely meeting the crescent Moon is sensed as familiar, perhaps even on a genetic level. That particular natural sky-motif gets repeated every couple of years - except rarely does it happen when Venus rivetingly shines at maximum brilliance. That's what's so special about the conjunction coming up on February 27. So if you missed last Monday night's conjunction, stand by; the best is yet to come.