How do astronomers predict a solar eclipse time and location at such precise accuracy?

by brunosan
Question by Freezing Temperature: How do astronomers predict a solar eclipse time and location at such precise accuracy?
What instruments do they use? How do they calculate it, roughly speaking?


Best answer:
Answer by Randy PBecause we have knowledge of the exact positions of the sun, moon and earth to very high precision going out many decades. These orbits are perturbed by the existence of the other planets, but computer models can easily account for all that and calculate the orbit to high precision.

It helps that these things are kind of far away from each other. The same kinds of computer models can predict the positions of satellites orbiting close to the earth, which are perturbed not only by the sun and moon (and a tiny bit by the planets), but also by irregularities in the earth's gravitational field caused by the earth being non-spherical and having mass concentrations like mountain ranges.

These perturbations are big enough that the agencies that track stuff in orbit around the earth send out orbital updates EVERY SINGLE DAY to keep everybody's models up to date with enough precision (frequently we're interested in knowing where satellites are down to small fractions of a meter. We don't need that much precision on the moon's position to predict an eclipse).

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