# How often is Venus this high? **URL:** \ **Category:** Factual Questions\ **Created:** [December 11, 2002, 1:54pm UTC](https://boards.straightdope.com/t/how-often-is-venus-this-high/141995 "2002-12-11T13:54:24Z")\ **Posts on this page:** 10\ **Page:** 2
**Author:** ![Podkayne](https://avatars.discourse-cdn.com/v4/letter/p/edb3f5/32.png) [@Podkayne](https://boards.straightdope.com/u/Podkayne)\ **Post date:** [December 11, 2002, 5:03pm UTC](https://boards.straightdope.com/t/how-often-is-venus-this-high/141995/21 "2002-12-11T17:03:31Z")
> [@](#): > > \*Originally posted by Jerevan Somerville \* > But I suppose the elliptical nature of planetary orbits might mean the maximum observable elongation is somewhat larger (~48 degrees). Yes? \*\* Correct. NB: What I calculated before was the Earth-Sun-Venus angle. The separation of Venus from the Sun is the Venus-Earth-Sun angle, asin(0.723/1)=46.4 degrees (=90-43.7) Sorry for any confusion. Earth’s eccentricity is 0.017 and Venus’ is 0.007. To maximize the separation, you’d want Earth to be at perihelion (its closest approach to the Sun) at (1-0.017)_1AU=.983AU and Venus to be at aphelion, at (1+0.007)_.723=0.728 AU, yeilding a separation angle of 47.8 degrees. ---
**Author:** ![scotth](https://avatars.discourse-cdn.com/v4/letter/s/b9e5f3/32.png) [@scotth](https://boards.straightdope.com/u/scotth)\ **Post date:** [December 11, 2002, 5:21pm UTC](https://boards.straightdope.com/t/how-often-is-venus-this-high/141995/22 "2002-12-11T17:21:30Z")
> [@](#): > > \*Originally posted by Algernon \* > \*\*Thanks **Podkayne** for resolving my somewhat inane question (and supplying the trig that has disappeared irretrievably into the black hole of my memory). > > **scotth** , is Venus typically visible to the _naked eye_ all day? (if you know where to look, and if it’s not too angularly close to the sun) \*\* I have seen it during the day with naked eye. You just have to know exactly where it is. It isn’t real easy. But, if you have a telescope already pointing at it, you can do it. ---
**Author:** ![ftg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ftg/32/2801_2.png) [@ftg](https://boards.straightdope.com/u/ftg)\ **Post date:** [December 11, 2002, 5:55pm UTC](https://boards.straightdope.com/t/how-often-is-venus-this-high/141995/23 "2002-12-11T17:55:05Z")
Back to the OP, the cycle of Venus-Earth positions cycles about every 584 days. (Yes, that’s close to the sum of the length of their years but it’s just a coincidence.) That is, conjunctions, etc. occur every 584 days. The maximum elongation in the evening occurs that often as well. So that 584 days from now it will be about where it is now in the sky (from our perspective). The Mayans were supposedly very keen on this cycle. ---
**Author:** ![Algernon](https://avatars.discourse-cdn.com/v4/letter/a/a183cd/32.png) [@Algernon](https://boards.straightdope.com/u/Algernon)\ **Post date:** [December 11, 2002, 6:15pm UTC](https://boards.straightdope.com/t/how-often-is-venus-this-high/141995/24 "2002-12-11T18:15:58Z")
Thanks **ftg**. That coincides with my estimate from the graph of about 20 months. Did you just _know_ this obscure fact? My amazement of the facts that you Dopers know (or know how to find) is boundless. ---
**Author:** ![scotth](https://avatars.discourse-cdn.com/v4/letter/s/b9e5f3/32.png) [@scotth](https://boards.straightdope.com/u/scotth)\ **Post date:** [December 11, 2002, 6:20pm UTC](https://boards.straightdope.com/t/how-often-is-venus-this-high/141995/25 "2002-12-11T18:20:47Z")
> [@](#): > > \*Originally posted by Algernon \* > \*\*My amazement of the facts that you Dopers know (or know how to find) is boundless. \*\* Stick around, you’ll get good at too. For my part, I looked up the distance of each planet to the Sun. For the geometric drawing, I just created that in my head. I didn’t even draw it for myself. ---
**Author:** ![David\_Simmons](https://avatars.discourse-cdn.com/v4/letter/d/9de053/32.png) [@David\_Simmons](https://boards.straightdope.com/u/David_Simmons)\ **Post date:** [December 11, 2002, 6:23pm UTC](https://boards.straightdope.com/t/how-often-is-venus-this-high/141995/26 "2002-12-11T18:23:31Z")
> [@](#): > > \*Originally posted by Algernon \* > \*\ ***David** , that is interesting. _All_ day? Or just a few hours after sunrise? (or a few hours before sunset when it’s visible after sunset) > > Is it more a function of where you live? Or that you know where to look? \*\* All day. I have seen it morning noon and night. It has been difficult lately because there has been a lot of forest fire smoke hanging around. I live on the desert where horizontal visibilities of 100 miles are common. In fact you can visually navigate by air from here clear over past Albuquerque without using a map. From here, when you get airborne a ways, you can see Charlston Peak just west of Las Vegas, NV. Then before you lose sight of that peak behind you, you can see Humphries Peak at Flagstaff, AZ coming up. And before losing sight of that you can see the Sangre de Cristos in New Mexico. It’s a good idea to have maps though because you cross the Continental Divide where there can be clouds which restricti visibility even on the desert. ---
**Author:** ![ftg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ftg/32/2801_2.png) [@ftg](https://boards.straightdope.com/u/ftg)\ **Post date:** [December 11, 2002, 7:14pm UTC](https://boards.straightdope.com/t/how-often-is-venus-this-high/141995/27 "2002-12-11T19:14:55Z")
> [@](#): > > \*Originally posted by Algernon \* > Thanks **ftg**. That coincides with my estimate from the graph of about 20 months. > > Did you just _know_ this obscure fact? My memory was actually 484 but I decided to check to be sure. I did a Google on “Venus Conjunction” and probably another word I’ve forgotten. I noticed the similarity to the sum of the years so I checked it: 365x = 224(x+1) gives the fraction of an Earth orbit for Venus to go around that plus 1 orbit. Multiply by 365, tada. It’s a little off from 584 but since the Earth’s year is really 365.254 (which I do remember), etc., close enough. I also remember that Venus’s orbit is a little over .7 A.U., so I could have roughed out the other calc. in my head too. Not an Astronomer. I just remember stuff. ---
**Author:** ![Algernon](https://avatars.discourse-cdn.com/v4/letter/a/a183cd/32.png) [@Algernon](https://boards.straightdope.com/u/Algernon)\ **Post date:** [December 11, 2002, 7:44pm UTC](https://boards.straightdope.com/t/how-often-is-venus-this-high/141995/28 "2002-12-11T19:44:17Z")
> [@](#): > > I just remember stuff. Now _there_ is an understatement. Heck, I can’t even remember stuff from _yesterday_. I’m impressed. (and that goes for all of you) ---
**Author:** ![Jerevan\_Somerville](https://avatars.discourse-cdn.com/v4/letter/j/c37758/32.png) [@Jerevan\_Somerville](https://boards.straightdope.com/u/Jerevan_Somerville)\ **Post date:** [December 11, 2002, 8:51pm UTC](https://boards.straightdope.com/t/how-often-is-venus-this-high/141995/29 "2002-12-11T20:51:59Z")
I happened to know the maximum elongation of Venus – though I did not know to call it that – from my astrological work, where the _aspects_ (elongations) between any two planets can have a specific significance, particular those in multiples of 30 or 45 degrees. In my table of interpretations for Sun-Venus aspects, it tells me that the maximum separation is 48 degrees, and therefore most major aspects (60, 90, 120, 135, 180 degress) will never occur between these two. Incidentally the maximum elongation of Mercury, according to the same table, in 28 degrees, not 36 as I stated earlier from memory. For some reason I _always_ get it wrong that way. At least I’m consistent! ---
**Author:** ![scotth](https://avatars.discourse-cdn.com/v4/letter/s/b9e5f3/32.png) [@scotth](https://boards.straightdope.com/u/scotth)\ **Post date:** [December 11, 2002, 9:37pm UTC](https://boards.straightdope.com/t/how-often-is-venus-this-high/141995/30 "2002-12-11T21:37:47Z")
> [@](#): > > \*Originally posted by Jerevan Somerville \* > \*\*from my astrological work \*\* There’s the problem. [Previous page](https://boards.straightdope.com/t/how-often-is-venus-this-high/141995.md?page=1)