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If March equinox is on 20th March (see the table in the link), according to it, when is the time that the sun enters Taurus? Is it on April 19 or April 20?

Reckless Glacier
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  • Looking at Stellarium: Looks like the Sun crosses into Taurus this year around May 13-14. – notovny Apr 09 '20 at 18:49
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    And from Guide9, about 18.00 UT on 13 May is when its leading edge hits the boundary between Aries and Taurus - at least for the astronomical constellations. – Dr Chuck Apr 09 '20 at 19:16
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    I'm voting to close this question as off-topic because astrology – James K Apr 09 '20 at 21:08
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    @James K What astrology in that? It is pure astronomy! It is the second time you call my question astrology while I'm interested in astrology at all, but I'm interested in the history of the astronomy. – Reckless Glacier Apr 09 '20 at 21:36
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    James K has a point, the Sun's λ=30° date is of little interest outside astrology. If there's an astronomical purpose, you need to show what it is, not just claim that there is one. – Mike G Apr 09 '20 at 22:21
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    My purpose is to understand the differences between the 'previous' astronomy to the current one. Data of astronomy out of date is still astronomy and still studied in astronomy departments at any respected university. – Reckless Glacier Apr 09 '20 at 22:31
  • Sorry, "it's about history" is not very convincing when the question is about the present year. – Mike G Apr 09 '20 at 23:10
  • Sorry, what's wrong if I want to learn the history of the astronomy according the present? I compare the methods. It's pure astronomy, nothing with astrology. If you suspect me that it isn't my purpose, so then what it can be? If you insist that I'm astrologist or believe in this nonsense, I give up. – Reckless Glacier Apr 09 '20 at 23:22
  • I want to learn the history of the astronomy according the present I have no idea what that means, but asking for a future date for something to happen seems quite unconnected to history. There is, BTW, a History of Science and Mathematics SE. – StephenG - Help Ukraine Apr 10 '20 at 21:52
  • If you learnt about something that it's out of date, and you are going to make an experiment about it next month, in order to understand it historically what was wrong with that, so to your opinion it is unconnected to history? Thank you for the useful site that I didn't know. – Reckless Glacier Apr 10 '20 at 23:35
  • You could use stellarium to figure this kind of thing out. – usernumber Apr 11 '20 at 08:45

1 Answers1

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Guy Ottewell makes a comprehensive Astronomical Calendar each year. From the 2020 edition:

8959.117 Apr 19 SUN 15    Sun enters the astrological sign Taurus, i.e. its
                          longitude is 30°

That's 2020-04-19 ~15h UT, which falls on April 20 in far eastern terrestrial longitudes and April 19 everywhere else. The next such event is 1 tropical year (365d 5h 49m) later.

8983.315 May 13 Wed 20    Sun enters Taurus, at longitude 53.48° on the eclip-
                          tic

The Sun enters the constellation at 2020-05-13 ~20h UT, which falls on May 14 in Asia, Australia, etc., and May 13 everywhere else. This event recurs 1 sidereal year (365d 6h 9m) later. In that time, the ecliptic longitude of the constellation boundary increases by 0.014°.

Mike G
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