Ok gang. Moon puzzle:

We just were treated to a nice total eclipse of the sun, the moon magically covers up the sun at times. That is an extraordinary kind of event and we happen to be in the part of the cycle of history of the earth-moon system that that can happen. Here's the puzzle:
What year is destined to be the last year there will be a total eclipse?
The moon is receeding from the earth at the rate of about 2 CM
per year and you have a certain sized path of totality. So that totality will clearly get narrower and narrower as the centuries cringe on. So at some point the totality will be say, one inch wide, then its never to be seen again. What year is that?

Originally posted by sonhouse
The moon is receeding from the earth at the rate of about 2 CM
per year and you have a certain sized path of totality.

i hope you're not serious.

Originally posted by eldragonfly
i hope you're not serious.

Of course I am serious, total eclipses aren't forever. We are in a very special time where it can happen but some time in the future there will be no more totality.

Originally posted by sonhouse
Of course I am serious, total eclipses aren't forever. We are in a very special time where it can happen but some time in the future there will be no more totality.

If you mean a total eclipse and not only a ring-formed eclipse, you are absolutely right, there is a last eclipse coming, sooner or later.

But we are *not* in a very special time where it can happen - the very last true total eclips lies in the far future, long after man (as we know her) walks on the ground.

It is quite easy to calculate (with a rough approximation) when the last total eclipse will happen, with the aid of some trigonometry and the knowledge how fast moons orbital radius grows.

Originally posted by FabianFnas
If you mean a total eclipse and not only a ring-formed eclipse, you are absolutely right, there is a last eclipse coming, sooner or later.

But we are *not* in a very special time where it can happen - the very last true total eclips lies in the far future, long after man (as we know her) walks on the ground.

It is quite easy to calculate (with a ro ...[text shortened]... happen, with the aid of some trigonometry and the knowledge how fast moons orbital radius grows.

You are correct in that. It has to go out 14600 miles and it receeds at 3.8 Cm/Yr. That adds up to about the year 607 million CE. Here is one little trick I figured out, maybe you heard it first here! (Sometimes I get the feeling I never actually invent stuff but am just a good plucker out of the air of ideas already floating around)
Disclaimers aside, we all know about sundials or sunclocks.
Well knowing the date of the last total, you can see a continuum of
time and if you measure the size of the footprint you can see what year you are in if you happen to be a lost timetraveler. A simple land based Lunar clock. Going back in time from now, the footprint gets larger by a tiny amount per year so when it goes that when it is in 14600 miles the footprint will presumably be twice as large as it is now,
so that defines 600 million years in the past. That can work farther back in time than that, I imagine the first few total eclipses were whoppers in terms of footprint size.
So there you have it, a LUNAR clock. We'll see if anyone comes back with a rebuttal of my claim to this idea, no way of telling if other people though about it till they talk about it, eh!

Originally posted by sofar55
IT'S NOT MACICAL IT'S SCIENCE

Science IS magical - poethical speaking.
People calling others for morons are not.

Originally posted by FabianFnas
Science IS magical - poethical speaking.
People calling others for morons are not.

Nobody going to comment on my apparent discovery here? Anyone else noticed this, the lunar clock idea?
Imagine time travelers lost in time, they have no idea what time they are in, all they have are radios which can talk across a few thousand kilometers reliably and some binoculars and some transport, cars, airplanes, horses, snowmobiles, whatever. They wait till they see an approaching eclipse, prepare themselves by going to what they hope to be the edges of the footprint and with filtered binoculars they establish both edges with usable accuracy, then use those figures to find out approximately what era they are in.
See, the problem for them is, in order for them to get back home they have to know as close as they can, what year it is. When they get a decent estimate of that by the lunar clock method they can use the binoculars to maybe see if there are noticiable star patterns that can pin it down further. If you are in some unknown time, it could be 300 million years in the past, say before even dino's or 300 million years in the future where probably all traces of humanity will have disappeared. You could maybe use biological data for the past but how would they know what is to evolve in the future? If they went say 700 million years into the past, they might end up before even the Cambrian so they would be SOL there and even the continents wouldn't tell them a whole lot since there can be a couple of crashes of the landmasses and separations in that time.

What a looney.

Originally posted by sonhouse
Nobody going to comment on my apparent discovery here? Anyone else noticed this, the lunar clock idea?
Imagine time travelers lost in time, they have no idea what time they are in, all they have are radios which can talk across a few thousand kilometers reliably and some binoculars and some transport, cars, airplanes, horses, snowmobiles, whatever. They wa ...[text shortened]... ole lot since there can be a couple of crashes of the landmasses and separations in that time.

err-right.
That explains everything then.
What times last orders,want to be around for that.😀😏

Originally posted by Bowmann
What a looney.

Well coming from you I'll take that as a compliment.

Originally posted by sonhouse
Nobody going to comment on my apparent discovery here? Anyone else noticed this, the lunar clock idea?

There are better and easier ways, not to mention safer ways, to discover the time at hand. Including pre-lunar and post-lunar eras.

Originally posted by FabianFnas
There are better and easier ways, not to mention safer ways, to discover the time at hand. Including pre-lunar and post-lunar eras.

I'm all ear.

Originally posted by sonhouse
I'm all ear.

Now, this is kind of a hypothetical problem. There is no time travel possible.

And if it is possible and you would like to tell the time, from Big Bang and forward to the End of Time – you only have to look at your hypothetical wrist watch and tell the time from it.

If you're traveling in time, then you have a lot of more difficult problems to deal with than just knowing when you are, like where you are, even in what universe you are in.

But in a hypothetical question with a hypothetical problem you can only try it with a hypothetical solution and hope it will work.

Time travel does not work. That has my grand grand grand son already told me from the 22rd century.

Originally posted by sonhouse
I'm all ear.

What happened to your other?