Seems odd that they go from not being near one another at all (to partially cover) to suddenly being perfectly lined up.
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The sun moves across the sky by it’s own diameter from our point-of-view in about 15 minutes, and the Moon moves a bit faster (again from our POV). If the Moon orbited more slowly, and the Earth turned more slowly, eclipses would last longer even to the extent of lasting days. And if they moved more quickly, the opposite would be true.
As it is, the Moon is directly opposite the Sun as seen from Earth two weeks prior to a Solar eclipse (the Moon rises at about the same time as the Sun sets), then as the Moon orbits it appears to be “catching up” with the Sun getting closer each day, if you go out and watch the sunrise or sunset you might see the “toenail” Moon in the last day or two before the eclipse, after which it approaches too close the Sun (from our POV) and is lost in the glare. The eclipse is only the two or so hours that it takes the Moon to completely pass the Sun in the sky, but it has been “lining up” for a couple of weeks at that point…lining up, but not covering. The covering only lasts a couple of hours. Then, the next day (or maybe two days) you’ll see the toenail Moon again around sunrise and sunset but it will be way off to the side. If you have a local landmark which is between you and the sunset, like a building or a hill, you can watch and see that both the Moon and Sun will set at the identical spot relative to that landmark in the few days both before and after the eclipse, but a month before or a month after they will set at different spots compared to the same landmark.
This is because the Moon and the Sun trace off-set paths in the sky as seen from Earth. If you imagine a race track with steeply banked corners, the cars sometimes take the curve very high on the bank and sometimes very low. The perspective from Earth is that the Moon and Sun take similar paths high or low, and only occasionally line up — most of the time one is high and the other is low, or vice-versa but every once in a while both take the same course as seen by observers on Earth. On a race track, a car overtaking on a curve would cause a crash if it followed the same line as the one ahead and fortunately that part of the analogy doesn’t translate into orbital mechanics, the Sun and Moon are far enough apart that they only *appear* to be following the same line through the sky and they don’t actually collide; but hopefully the analogy is at least a little bit useful.
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