How are solar and lunar eclipses predicted?

Answer 1

The ancients were aware of relationships like the Saros, which give rough predictions. Now eclipses are predicted by computing the locations of the Sun, Moon and Earth, then looking for times when they line up.

There are two common ways to compute the locations. One is by numerical integration (e.g. Solex by Aldo Vitagliano), the other is through analytical solutions like VSOP87 and ELP2000.

Once the eclipses are found the information about them may be communicated with maps and tables, or by parameters called Besselian Elements. These allow you to compute the path and local circumstances yourself.

You can chew up a lot of computer time playing with this stuff! :-)

Answer 2

The motions of the earth and moon are very well known and easy to predict. Lunar eclipses, where the earth's shadow obscures the moon, are fairly common. Solar eclipses, where the moon obscures the sun, are less common, but still easily predicted.

Answer 3

The duration of the revolution of the moon around the earth and the duration of the revolution of these two around the sun is different.This causes peculiar positioning of these celestial bodies in such ways that the moon can block the sunlight(solar eclipse) or the earth can cast its shadow on the moon(lunar eclipse).Since we can now calculate where these celestial bodies will be at a particular time,eclipes can be predicted easily.

Answer 4

The positions and motions of the earth, sun and moon have been measured very precisely. Computer models use the laws of motion and gravity to calculate when these bodies are aligned in such a way to produce an eclipse.