In the famous eight-year cycle of Venus, 2017 repeats almost exactly the phenomena of 2009.
The eight years of the cycle have their quite widely differing characters. The character of the 2009-2017-2025 type of year centers on an inferior conjunction (passage between Earth and Sun)
at which Venus misses the Sun high on the northern side. This gives – for north-hemisphere observers – exciting opportunities to see Venus surprisingly close to the date of conjunction, which is tomorrow, March 25.
Moments after sunset, Venus is below ground. But with care you may be able to see it down to moments before sunset.
South-hemisphere people miss out, but they have their similar opportunity during years of the 2007-2015-2023 type, when, conversely, Venus passes as far as possible south of the Sun.
At the start of 2017, Venus was the conspicuous “evening star,” out at its easternmost from the Sun on Jan. 12. Then it rushed at increasing apparent speed on its curve inward to overtake us on the inside, its shape in the telescope becoming an ever larger but thinner crescent.
Part of the chart for Venus in the evening sky, from Astronomical Calendar 2017.The planet’s disk is vastly exaggerated in size; the real size would be more like the dot.
This swoop down the sunset skies was as in the prelude to every inferior conjunction – with the difference, in this year of the cycle, of what happens at the end, which was determined by what happened at the beginning. Only five days after the Jan. 12 extreme of elongation, Venus ascended northward across the ecliptic plane. Therefore it curved northernmost above the plane on March 14, and on March 25 will pass as much as 8.29° north of the Sun. All parameters slowly change, and the amount of this clearance is increasing from cycle to cycle as the dates of northernmost latitude and inferior conjunction get closer together:
2009 Mar 27 8.16°
2017 Mar 25 8.29°
2025 Mar 23 8.41°
2033 Mar 20 8.52°
2041 Mar 18 8.61°
2049 Mar 15 8.68°
It would have been better if I had had these proclamations about Venus ready at an earlier stage in her dive to the sunset, but she herself held me up. That is, I became involved in working on my program to draw a compound illustration for the whole eight-year cycle, and ran into puzzles that had me using hot language for at least three days. (Not to mention other distractions such as a mistaken journey on equinox day.) Please look – tomorrow – at the growing “Astronomical Calendar 2017”, accessible through the link above. In the section for Venus, I shall have put this illustration and more about the cycle of Venus.
(Not the Girdle of Venus. This was the secret of her allure, and when lent to or stolen by other females made them irresistible too. But now it is also the name of a species of comb jelly, and in palmistry it means a line from between your index and middle fingers to between your ring finger and pinkie.)
Due to cloudy and rainy weather, hilly topography, other commitments, and a bit of fatigue, I didn’t manage to see Venus on the same morning and evening. As matter of fact, I didn’t see Venus at all for a week. But this morning, ten minutes before sunrise, from the back stairs of my home, I saw Venus about three degrees above the trees on the ridgeline of Potrero Hill in San Francisco. Two days after inferior conjunction. She was a breathtakingly thin crescent through 8×42 binoculars. I was somewhat morose until I saw Venus, and I’ve been happy and energized since.
Guy, thanks for calling attention to what is, for me, one of the most exciting planetary skywatching experiences, a Venusian inferior conjunction. Thanks to good weather and some perfectly flat horizons along the Rappahannock River here near Fredericksburg, Virginia, I’ve been able to see Venus for several days now both just before sunset and a few minutes before sunrise. I’m hoping we have clear skies tomorrow so I can attempt something Fred Schaaf once challenged observers to do, which is observe Venus at the *moment* of inferior conjunction. I better consult your table of events to see exactly when that is!
I’ve never before heard of the Girdle of Venus, but I have read about the “Belt of Venus”, which supposedly is the pink-blue-gray color belt in the eastern sky after sunset, rising up from the horizon as the Earth’s shadow is cast on the atmosphere. A captivating sight in its own right . . .