ANSWER:
Solar and lunar eclipses always come in pairs, with one following the other in a period of one fortnight (approximately two weeks).
STEP-BY-STEP EXPLANATION:
A lunar eclipse happens when the Earth, sun and moon align in space, with Earth between the sun and moon. At such times, Earth’s shadow falls on the full moon, darkening the moon’s face and – at mid-eclipse – usually turning it a coppery red.
A solar eclipse happens at the opposite phase of the moon – new moon – when the moon passes between the sun and Earth.
The moon takes about a month to orbit around the Earth. If the moon orbited in the same plane as the ecliptic – Earth’s orbital plane – we would have a minimum of two eclipses every month. There’d be an eclipse of the moon at every full moon. And, one fortnight (approximately two weeks) later there’d be an eclipse of the sun at new moon for a total of at least 24 eclipses every year. But the moon’s orbit is inclined to Earth’s orbit by about five degrees. Twice a month the moon intersects the ecliptic – Earth’s orbital plane – at points called nodes. If the moon is going from south to north in its orbit, it’s called an ascending node. If the moon is going from north to south, it’s a descending node. If the full moon or new moon is appreciably close to one of these nodes, then an eclipse is not only possible – but inevitable.
