Ten minutes of doubt

A birth chart is really ten numbers: where the sun, the moon, five planets and two calculated points sit around a circle of 360 degrees, plus one more for the point of that circle rising over the eastern horizon at the moment of birth. Everything else on the chart is those ten numbers sorted into boxes.

Birth times are usually rounded. Studies of hospital records find written-down minutes piling up on the zeros and fives, far beyond what chance would give. So the essay puts the true moment anywhere in a ten-minute band, five minutes either side of the register entry, and asks what each number does across it.

Eight of them do almost nothing. The sun moves 25 arcseconds, less than half of one arcminute, and charts are printed to the arcminute. Mercury, the fastest planet from our point of view, manages 55 arcseconds. Those eight would be printed identically at 8:55 and at 9:05.

The moon moves about five and a half arcminutes, still tiny beside a 30 degree sign. But the moon's position also sets where a 120-year cycle of planetary periods begins, and there the same small arc stands for years. Ten minutes slides that whole schedule by two to seven weeks, depending on which planet rules the moon's star, and it slides as one piece: a date forty years out is off by the same amount as the first one.

The rising point moves about two and a half degrees, which is why it matters. How far exactly depends on your latitude, because the tilt of the zodiac against the horizon changes as you go north. The average is fixed at 2 degrees 30 minutes 25 seconds, but at Delhi a particular ten minutes can be anything from 2° 08′ to 3° 35′.

Then the essay prices the boxes. Cut a sign into nine and ten minutes changes which ninth the rising point is in three times out of four. Cut a sign into sixty and the answer changes every time, by about five cells.