Of course, it's still a watch, so it has standard hour, minute and seconds hands. The hands do not have lume, unfortunately, but they have a nice teal blue color that shows up clearly on the gold dial. The blue dial version has white-tipped hands, I do not know if they have lume on their tips.
The uppermost portion of the dial is a fixed chapter ring around the outside edge, with squares marking the 12 hours, and small hatches for minutes, above the names and numbers for the twelve months. At the lower edge of this ring is a very finely divided track which marks the days of each month.
Slightly thicker lines mark the days numbered 1,11, Inside of the horizon ring marks the visible sky, and outside of this ring marks the stars that are hidden behind the horizon. It turns once every 23 hours, 56 minutes, 3. It moves counterclockwise because it shows the relative apparent motion of the sky opposite to the earth's clockwise rotation. This main dial has a huge amount of information packed onto it, including major constellations, visible objects 4.
It also shows the solar mean disk marked with the numbers of the month. I found this solar display to be the easiest way to set the watch. Because it doesn't turn at the same rate as the 12 hour hands, it soon becomes clear that we need a calibrated start point, so the dates make sense along the edge as sidereal time slips earlier by 4 minutes each day.
That gets really complicated. I found a little gem hidden away in the technical manual for the Citizen watch caliber. It explains a short cut using the date markers on the Solar Mean disk and published sunrise information for your current location. Here are simple steps: 1 look up the sunrise time for your city, for today's date. Websites will show this, as will the weather page of a newspaper remember those?
In my example below I use July 11, , with sunrise at AM. Rotate the disk counterclockwise until today's date on the Solar Mean lines up to the Eastern horizon line, corresponding to sunrise. Repeat the above procedure if it did slip. Once satisfied, move the time ahead to the current time on the same day. You can see from the pictures below that once I set the correct sunrise time for my date, I can track the position of the sun from the watch dial by tracking the motion of today's date, on the Solar Mean disk, as the watch face turns.
At noon, you can see that July 11 crosses the meridian line close to the zenith. Later, at around in the afternoon, it has moved towards the southwest horizon, and it should cross the sunset line around PM. As the seasons progress, I will see these times change as the earth's position changes relative to the sun. In the meantime I can locate today's date on the outer chapter ring, and learn what the current sidereal time is relative to UTC.
That would be useful if I wanted to calibrate a telescope, for example, or decide when to send a satellite into space. I hope this didn't completely bore you. I thought a resource like this might prove helpful for those nutters like me who enjoy these sorts of toys. A solar day is, therefore, nearly 4 minutes longer than a sidereal day: Because the Earth orbits the Sun once a year, the sidereal time at any one place at midnight will be about four minutes later each night, until, after a year has passed, one additional sidereal day has transpired compared to the number of solar days that have gone by.
Maps of the stars in the night sky usually make use of declination and right ascension as coordinates. These correspond to latitude and longitude respectively. While declination is measured in degrees, right ascension is measured in units of hours and minutes. In the sky, the meridian is an imaginary line going from north to south that goes through the point directly overhead, or the zenith.
Right ascension of any object currently crossing the meridian is equal to the current local apparent sidereal time. But although I am a very serious amateur astronomer and thus attracted to this device, I had to admit to myself that I would not find its functionality attractive for astronomy. Here's why. The planisphere, while beautiful, is simply too small. Perhaps the 10x magnifier will ease that problem.
And XX:XX o'clock is almost never the current time. Rather it's next Friday night at PM, or some other time in the future.
Obviously telling the time of day is a bit of a challenge. Genuinely sorry indeed to be negative. Once again, it's truly beautiful. When Robert first told me it was inbound I wanted one too. I wrote to him, "Looks like something I should be interested in". Your comments are well directed. Indeed the Astrodea has much more "cool factor" than it does practicality to an astronomer. But then, most could argue that dive watches were made obsolete by the dive computer, yet dive watches seem more popular than ever.
To address your 3 points: 1 Totally agree - the dial is very small for any practical use, although the loupe does help.
In part, I think it's the miniaturization that makes the whole thing so cool. You look up the sidereal time for the date you wish to view the sky, pull the crown out to the first step and rotate the sphere until the sidereal time lines up to the date of interest. Then, when done, you turn the disk back to the spot where it was before, corresponding to "now"; 3 It's actually quite easy to read the time. The hands are narrow, but show up very clearly on the dial, and the hour and minute markers are rather clear on the outside edge Plus, using the date display assumes that you already know the date, and you use that info to line up the other functions.
So, it's a different approach, certainly. Thanks for contributing such thoughtful commentary! Updated Sep 4, at PM by skywatch Tags: astrodea , astronomy , citizen , planisphere. That is a complicated watch! But it's beautiful and interesting, at the same time. Thank you very much for the - very informative - review.
I plan to write some new blogs after I get a deadline out of my way. Dan R - Sep 7, PM. With my poor eye-sight, I could not use it. But thanks for the wonderful post and explanation. Latitude Northern Hemisphere. A Warranty and English instruction manual. Secrets to successful science fair projects. At xUmp. We sell everything from educational toys, teacher supplies for science classroom, lab equipment, science toys, science fair supplies, classroom equipment, chemistry glassware, chemistry lab equipment, physics demos, electronics supplies, robots, science kits to geeky science gifts.
Toggle navigation. Share this product:. Astrodea Moon Celestial Watch. Contact us for product availability update. We have 0 pcs in stock. Weight: 1 lb 2 oz 0. Not for children under 3 yrs. Customer Reviews There are no customer reviews for this product.
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