Science
Related: About this forumThink 12 or 24 hour watches are a little short-sighted?
The Midnight Planétarium timepiece tracks the position of the six planets visible from Earth. Each of them are independently controlled for precise tracking at any given time and their true orbital speeds are represented. Aside from keeping you updated on planetary positioning, it also functions as a regular watch with the shooting star indicating the time in hours and minutes.
Designed by Van Cleef & Arpels
Callmecrazy
(3,065 posts)kcass1954
(1,819 posts)for the next 6 or 8 years.
roguevalley
(40,656 posts)I want to know when its dinner time on Mars.
Jim Lane
(11,175 posts)It supposedly "tracks the position of the six planets visible from Earth." If they mean visible to the naked eye, there are five -- Mercury, Venus, Mars, Jupiter, and Saturn. If they allow use of a telescope, that adds Neptune and Uranus for seven. If they count the Moon as a sixth planet (which it isn't) just because it's visible, then they'd have to count the Sun for seven.
It seems contorted to say that the Earth is visible from the Earth, but that's the only way I can see to get to six.
defacto7
(13,485 posts)muriel_volestrangler
(101,405 posts)It has a close-up: http://www.vancleefarpels.com/us/en/article/10935/midnight-planetarium-timepiece
I'm interested in "their true orbital speeds are represented". Does this mean they've successfully replicated the varying angular velocity of an elliptical orbit - even though the watch clearly uses circles for the path? This is non-trivial - on Mercury, the angular velocity varies so much that you would see the Sun move backwards in the sky for a few days each 'year': https://en.wikipedia.org/wiki/Mercury_%28planet%29#Orbit_and_rotation . Since Kepler's 2nd law says equal areas are swept out in equal time in an orbit, and the area is proportional to the square of the distance from the Sun, then the angular velocity is equal to the inverse square of the distance - and the distance varies by over 50%, so the angular velocity varies by over 100%.
Jim Lane
(11,175 posts)The biggest revelation from your post was the Sun's retrograde motion to a Mercurian observer. When I was in school, back when Pluto was a planet, we were taught that Mercury was tidally locked to the Sun, so there was no apparent solar motion at all. I didn't know that, since then, it had started rotating. (I did know that Jupiter had somehow picked up more than 50 extra moons. I wish the Solar System would quit changing like this!)
As for the watch, I agree with your criticism. Representing the Earth as a perfect sphere is no big deal, because the difference is so tiny, but the diagram in the Wikipedia article shows that the difference between Mercury's orbit and a perfect circle would be visible to the naked eye even at the scale of that watch face.
Also, I wonder -- if the thing happened to stop for some reason, how would you accurately reset it after the repair?
muriel_volestrangler
(101,405 posts)will be able to pass on the expense of the firm telling them the position to reset it in. I think someone could also produce an electronic version with a colour LCD screen that accurately plotted the planets' paths far cheaper, and have other options too.
Yeah, I do find the "sun goes backwards for a few days, seen from Mercury" factoid slightly mind-blowing.