The brightest planet will on October 26 rush between us and the Sun.
I’m early in getting this to you, because I shall be away on a journey – rushing, indeed, closer to the Sun – from tomorrow until October 25.
The phenomenon is called the planet’s inferior (“lower”) conjunction. It happens each 19 and a half months (5 times in each of the famous Venus 8-year cycles). And each of these 5 recurring occasions has its sharply different character, because of happening at a different position in the orbits of Venus and Earth around the Sun.
Here are pictures of the scene just before sunset at the previous passage (2017 March 25), the present one, and the next (2020 June 3).
The planet is shown over a span of 20 days around the time of the conjunction with the Sun. Its slender Sun-illuminated crescent is exaggerated 150 times in size; the dot at the center of the crescent is the planet’s actual position (and nearer to its real size). The Sun is exaggerated only twice in size. You won’t see the details other than the Sun and – hopefully – Venus, but they tell you the way you’re looking into the solar system and the universe. Enlarge the pictures if you can.
In 2017-like years, Venus hurdles 8° north of the Sun, so that careful observers (masking out the Sun) get a chance to spot it around sunset near to or even on the day of conunction.
In 2018-like years, Venus sneaks by, 6° south of the Sun, so that the best opportunities are for southern-henisphere observers.
In 2020-like years, Venus comes close to passing exactly in front of the Sun, as it last did – a transit of Venus – in 2012
I have long contended that even though Venus’ inferior conjunctions of late October (1986, 1994, 2002, 2010, 2018 are the ones I’ve observed) are the worst “on paper” in terms of favorability of position with respect to the Sun, for us in the eastern U.S., they are among the easiest to observe, with our high probability of clear, transparent skies this time of year. I have been able to see Venus for several days in a row now in the middle of the day with 10×50 binoculars, and hope to be able to see it up to the 26th. All that’s needed is a porch to block out the Sun above, and look below it to see Venus in the blue sky.
And just to throw in a random comment, on a completely different topic: has anyone else noticed the huge misshapen X pattern in the sky that is being made by Vega, Deneb, Altair (at the center of the X), Saturn, and Mars? It looks like a vast version of the five star X pattern at the head end of Serpens (Caput). I only noticed it the other night under a bright Moon when only the brightest stars were visible.
This has been a difficult year to observe retrograde Venus before her inferior conjunction with the Sun. Last Saturday afternoon, October 6, I walked up Bernal Hill, where higher Twin Peaks to the west would hide the Sun before nominal sunset but the south-southwestern horizon would be unobstructed. Fifteen minutes before sunset I started looking for Venus through 10×42 image-stabilized binoculars. No luck until right around sunset, when she showed up as a dramatically thin crescent. Ten minutes after sunset Venus was still visible but atmospheric turbulence blurred her shape, and less than half an hour after sunset she disappeared into a bank of low clouds over the Pacific. I knew that would be my last view before inferior conjunction, so I bade her fare well during her journey through the underworld.
I’m looking forward to seeing morning-star Venus leap up from the eastern horizon after inferior conjunction!
P.S. — Bon voyage to you too, Guy.
Not sure if the colors used on the sky charts are new or not. They are new to me and I like them over the darker ones. My old eyes can make out the detail much better. Thanks.
Ohh, I see, so to speak the color reflects the sun being up. Duh.
Steve, the sky color is different because it’s a daytime scene – the Sun is above te horizon. I haven’t shown such scenes before. For night-time scenes, the sky will have to continue to be black or nearly so. Do you mean that this makes them difficult to read? I have elaborate wat=ys to try to make labels etc. contrast with their varying backgrounds.