Comment Re:Hmm (Score 1) 104
First, water vapour is opaque at visible frequencies, but the sun emits over a very wide band, most of which will totally ignore clouds. For something like this, you'd use radio astronomy. The sun is a superb radio source, easily strong enough to compete with terrestrial sources, especially if you pick the right frequency.
Second, no it wouldn't. It wouldn't be triggered by the presence of detecting light on the optical spectrum, but the presence of a specific alignment. So you only ever synchronise when you hit exactly the correct point.
You then want an interferometer to observe the sun, where the centre of your virtual dish is precisely the meridian. When the centre of the sun is precisely midway across your telescope's field of view, you transmit a synchronisation pulse.
Thirdly, a leap second is introduced every 21 months or so. If we assume a month of 30 days, that means you have clock drift of 1/630th of a second per day. You could miss a lot of days before the maximum possible error exceeded the minimum error in the clocks used. The risk of time travel would be zero.