A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Position-Finding
From: Frank Reed
Date: 2017 Dec 7, 11:35 -0800
In nine days the small asteroid Phaethon will be zipping across the night sky at an angular rate approximately triple the rate of the Moon. You can determine GMT and thus longitude by observing its position among the stars. And potentially, it works better than the Moon! As with lunars, in theory, you'll have to correct for parallax if you want to do this right, but since Phaethon will be about 36 times further away than the Moon's mean distance, the correction is only about 1.5' of arc which is about the same as the motion in one minute's time. That means that even if you ignore parallax completely, your GMT estimate would be wrong by only about a minute. You can't see this event with your sextant. You'll need a medium-sized backyard telescope. Details here.
Phaethon is also the source of the Geminid meteor shower which peaks next Wednesday, and this is one worth spending some time out in the cold. As Bob King says in his enthusiastic article, "This is it, the shower we've been waiting for." More here.
My advice to you all as fellow astronomy advice-gvers: if you suggest to family and friends that they go outside to watch for Geminids, you can't emphasize enough that they have to spend their time looking up. Obvious? No, not really. We're all so accustomed now to doing other things that feel "productive" --reading text messages, checking tomorrow's weather, looking at news headlines, updating calendars and to-do lists-- that it's hard to remember some activities actually benefit from inactivity. Meteors don't announce themselves with a whoosh, and all but the very brightets will not catch your attention "out of the corner of your eye". You have to be actively looking up, observing as much of the sky as you can, continuously, for as many minutes as you can stand it. Apart from that, there's no need to know "where" to look (generally east before midnight, west after midnight). If you're out anytime from about 9pm onward and you can see a substantial fraction of the sky without clouds, then you will see Geminid meteors. It's guaranteed. ....oh but there is that little problem of light pollution. Remind any prospective observers that they need to get as far away from lights as possible. And that includes those little internetful lights we carry around in our pockets that demand so much of our attention. In fact, screw it: just confiscate everybody's cell phones before they go outside! And then lock the door for at least twenty minutes. No one gets back in without a Geminid count! :)
Hey, speaking of asteroids, and veering off-topic, what the heck is up with hat interstellar asteroid -- ten times longer than it is wide?! Paraphrasing Alec Guinness, that's no asteroid... it's a space station. And that's a reference with a connection to Pub.229. They both callback to 1977 nostalgia. ;)
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