Johannes Kepler
Posted: Mon May 04, 2020 1:45 am
(Responding to a question about Kepler's accurate birth time.)
I haven't had a Kepler chart in my files since I put the physical (paper) files in storage, but I do recall that he gave his own chart. Let's see what we can find.
Solar Fire has a B-rated chart for December 27, 1571, 2:30 PM LMT, Weil der Stadt, Germany. It claims that the data was taken from a horoscope Kepler himself drew at age 26 "as transcribed in Éric Lindemann's book, Mécanique: Une introduction par l'histoire de l'astronomie which said, "Johannes Kepler, conçu le 16 mai 1571 à 4 heures 37 du matin, est né le 27 décembre à 2 heures 30 de l'après-midi." Quite an astonishing entry, as it gives his conception date and time and then his birth date and time.
The LMT would be wrong. If this is the correct chart, then it would be 2:30 PM LAT, or Sun 37°30' in RA west of (earlier than) MC. With Sun at 286°47', this gives RAMC 324°17', or 1°47' later than the RAMC for 2:30 PM LMT. That would put the time (to the nearest minute on the clock) 7 minutes later or 2:37 PM LMT.
Why this doesn't count as an A record, I don't know (if, indeed, it was data from Kepler himself as seems to be alleged). Let's look at the Astro.com page: They give the same date, time, and rating and then give an "alternative birthtime." of 1:07 PM, which leads to the long Source Notes section.
The claim is that a different biographer quoted Kepler discussing his own chart and saying he had 25° (Tropical) Gemini rising and 22° Aquarius culminating. This is exactly what we get for the 2:37 PM LMT (2:30 PM LAT) I calculated above. Another author quotes a different chart allegedly drawn by Kepler for 1:00 PM LAT. The argument they give does make sense (though I can't say it's true), that Kepler started with a 1:00 PM time and then rectified it by prenatal epoch (otherwise, it's strange he would have given a conception time so carefully in the other entry).
So it depends on whether you want to go with Kepler's originally stated birth time (1:00 PM LAT = 1:07 PM LMT) or his rectified time (2:30 PM LAT = 2:37 PM LMT). The chart they quote matches this 1:07 PM time (to within about a minute).
The strangest thing to me is that the planet positions given in the chart allegedly drawn by him have planet positions not quite right. For example, Moon is about a degree off, even though the time is confirmed by the angles and house cusps matching. And this was the man who derived the formulae for calculating the planets! I suspect the explanation is that it was an early drafting of a horoscope before he worked out all that stuff.
The charts aren't all that different. I suppose I'd go with 1:07 PM LMT on the premise that it was the originally stated time and that a 90-minute rectification is absurd. It might be tempting to have the somewhat mystical Kepler have Neptune rising and Moon exactly conjunct Aldebaran, but that doesn't seem to be the birthtime given for him. Instead he has Moon rising and (most angular) Saturn just past Descendant, consistent with scientists; and also Pluto in the rising foreground.
I haven't had a Kepler chart in my files since I put the physical (paper) files in storage, but I do recall that he gave his own chart. Let's see what we can find.
Solar Fire has a B-rated chart for December 27, 1571, 2:30 PM LMT, Weil der Stadt, Germany. It claims that the data was taken from a horoscope Kepler himself drew at age 26 "as transcribed in Éric Lindemann's book, Mécanique: Une introduction par l'histoire de l'astronomie which said, "Johannes Kepler, conçu le 16 mai 1571 à 4 heures 37 du matin, est né le 27 décembre à 2 heures 30 de l'après-midi." Quite an astonishing entry, as it gives his conception date and time and then his birth date and time.
The LMT would be wrong. If this is the correct chart, then it would be 2:30 PM LAT, or Sun 37°30' in RA west of (earlier than) MC. With Sun at 286°47', this gives RAMC 324°17', or 1°47' later than the RAMC for 2:30 PM LMT. That would put the time (to the nearest minute on the clock) 7 minutes later or 2:37 PM LMT.
Why this doesn't count as an A record, I don't know (if, indeed, it was data from Kepler himself as seems to be alleged). Let's look at the Astro.com page: They give the same date, time, and rating and then give an "alternative birthtime." of 1:07 PM, which leads to the long Source Notes section.
The claim is that a different biographer quoted Kepler discussing his own chart and saying he had 25° (Tropical) Gemini rising and 22° Aquarius culminating. This is exactly what we get for the 2:37 PM LMT (2:30 PM LAT) I calculated above. Another author quotes a different chart allegedly drawn by Kepler for 1:00 PM LAT. The argument they give does make sense (though I can't say it's true), that Kepler started with a 1:00 PM time and then rectified it by prenatal epoch (otherwise, it's strange he would have given a conception time so carefully in the other entry).
So it depends on whether you want to go with Kepler's originally stated birth time (1:00 PM LAT = 1:07 PM LMT) or his rectified time (2:30 PM LAT = 2:37 PM LMT). The chart they quote matches this 1:07 PM time (to within about a minute).
The strangest thing to me is that the planet positions given in the chart allegedly drawn by him have planet positions not quite right. For example, Moon is about a degree off, even though the time is confirmed by the angles and house cusps matching. And this was the man who derived the formulae for calculating the planets! I suspect the explanation is that it was an early drafting of a horoscope before he worked out all that stuff.
The charts aren't all that different. I suppose I'd go with 1:07 PM LMT on the premise that it was the originally stated time and that a 90-minute rectification is absurd. It might be tempting to have the somewhat mystical Kepler have Neptune rising and Moon exactly conjunct Aldebaran, but that doesn't seem to be the birthtime given for him. Instead he has Moon rising and (most angular) Saturn just past Descendant, consistent with scientists; and also Pluto in the rising foreground.