In having a satellite that is almost exactly the right apparent size to block the sun leading to total eclipses.
Why? Is it just coincedence (which is incredible) or something deeper?
Thanks
Coincidence. And in fact the apparent size of the Moon is inconstant as the Moon is sometimes farther away than at other times in its orbit. Add to that the fact that millions of years ago, the Moon was much closer to the Earth, and hence would have appeared larger. Since it’s moving away by about 4 cm per year, eventually it will appear too small to completely cover the sun.
As Q.E.D. said.
We are fortunate the human race evolved when it did. I imagine that this cosmic coincidence would have been wasted on T.Rex.
Well, distance from the Sun is something, too.
If it’s in the proper plane, I’ll bet that Charon blocks the Sun from Pluto, since the Sun is so tiny that far away.
It’s possible that if you could stand on the surface of some of the outer planets (if they had a solid surface), that one or more of their moons would block the sun at times.
We went through this pretty thoroughly in this thread:
The Moon, Venus, and Probability
It’s easy enough to verify that. If you have a small telescope, you can take it out in your back yard and point it at Jupiter, and if you’re looking at the right time (several times per month), you can see the little shadows cast by the Galilean satellites onto the disk of Jupiter. A person on Jupiter, floating inside one of those shadows, would see a total eclipse of the Sun.
And yes, Charon casts a shadow onto Pluto–but only for a few years out of each 248-year orbit when the alignment is correct. One such period just occurred between 1985 and 1990. Charon is so close to Pluto, and the Sun is so far away, that the shadow covered a significant fraction of Pluto’s surface.
The unique aspect of the Earth-Moon situation, then, isn’t that the Moon causes total eclipses, but that it’s just barely big enough to do so. The apparent size of the Moon is sometimes bigger than the Sun, and sometimes smaller. I don’t know if that’s true of any other planet/satellite combination in the Solar System.