The Sun progresses on November 22 from Scorpio into Sagittarius, according to the ancient system of “signs.”
Detail from the Sun chart in Astronomical Calendar 2015. The smaller circles are true to the Sun’s apparent width of half a degree.
But in the actual sky, if we could see the Sun, we’d see it one constellation back, moving, at almost the same date, not out of Scorpius but into it.
This is very clear in a chart. You can see the scale of ecliptic longitudes, by which the 30-degree-wide astrological signs are defined (“Sagittarius” begins at 240). And you can see the irregular shapes of the actual constellations, defined with choppy lines to fit around the stars in the traditional pictures.
But a chart is sort of abstract. What you see when you go outside isn’t a chart, it’s your surroundings and the horizon and the tilted and revolving sky. Here is the view if you go out tomorrow evening, Sunday, Nov. 22.
Fit the chart mentally onto the twilight sky by means of that well-known teapot shape of Sagittarius, and that imaginary line traveled by the Sun, the ecliptic.
In the bright twilight you won’t be able to make out the stars of Sagittarius, and all too soon they will set (as you can tell from the motion-arrow on the celestial equator), so you’ll have to trust me that that’s where they are. The arrow through the Sun shows its motion over five days, centered on the time of the picture. Clearly, it has many days of journeying – a month, in fact – before it will enter the actual Sagittarius.
It has only one day to the moment when it enters actual Scorpius. (Nov. 22 15 UT into sign Sagittarius; Nov. 23 17 UT into constellation Scorpius.) You can’t see the stars of Scorpius, either, for an even better reason – they are, like the Sun, below the horizon. Them, too, you have to see in imagination, and an assist to that is that Saturn (marked though underground, like the Sun) is in Scorpius, where it has spent much of this year. It isn’t easy for a planet to be in Scorpius, because, as astronomically defined, that constellation possesses only a short piece of the ecliptic.
(To tell the truth, I’m rather tired of apologizing for that bit of pedantic irregularity. I feel that Messrs. Gould and Delporte could have brought themselves to draw Ophiuchus with shorter legs.)
– At this moment (well, half an hour ago, but while I was writing this) I receive the program of a conference that seems to be mainly about astrology, with its relation to astronomy and other sciences. I read the abstracts of the lectures and found them interesting.
I’m on the mailing list because I had expressed interest in an earlier conference on “Skyscape Archaeology.”