Moon can occult Venus. Venus can transit across the solar disc. Moon can elipse Sun. Can all three celestial events occur at the same time - Moon is at front of Sun (partial eclipse is fine) and Venus is behind Moon (ideally part of the planets is seen at lunar limb)? Observer is at Earth.

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    $\begingroup$ Now you've got me wondering if/when Venus and Mercury will transit simultaneously! $\endgroup$ – Carl Witthoft Apr 27 at 17:51

Yes, but such an event would be very rare. Venusian transits last only about 7 hours, and there are only two in 113 years, So Venus is in transit for about 0.0015% of the time.

So as a back-of-the-envelope calculation, you would need to see about 70000 eclipses before you had a combined transit/eclipse. There are about 2 solar eclipses a year, so you might hope to get this unusual syzygy once every 35000 years or so.

None are forecast.

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  • $\begingroup$ Thanks. Just a note - your estimate assumes that every position is possible. In fact, Venus and Moon must be at the nodes of their respective orbits, but since nodes of the Moon orbit moves along ecliptic in the 19 year cycle, everything is ok. $\endgroup$ – Leos Ondra Apr 27 at 9:11
  • $\begingroup$ I got closer to 8 hours in this answer was I wrong? $\endgroup$ – uhoh Apr 28 at 11:33
  • $\begingroup$ The assumption there is that Venus will cross the middle of the sun's disk (assumption of coplanaity) in fact Venus will usually cross in a shorter secant, so the time will be less. The last transit was rather less than 7 hours. The general idea though isn't worked out accurately enough for 7 or 8 to matter, the principle is that there is nothing preventing a combination of a transit and an eclipse, but such events would be very rare. $\endgroup$ – James K Apr 28 at 12:17

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