Any Near misses with Venus transits that may be visible in Ha.

[Tropo-Bob]

At the end of the transit of Venus in 2012, I could see Venus in front of prominences with my solar scope, after Venus had finished the transit in visible light.

I am seeking to find if anybody is aware of any modelling of near misses in the future, inferior conjunctions of Venus (or Mercury) to see if there is any chance of this been seen again before the next sheduled transit?

[OzEclipse]

Hi Bob,

Venus, not before 2030. Closest approaches 2017-2030 are

1.10 deg on 1 June 2028
1.25 deg on 3 June 2020

The parallax of Venus is 1' arc across 1 Earth diameter. If it were that close to be seen Ha, silhouetted against prominences, a large latitudinal shift should result in a transit somewhere else on Earth which would have been predicted.

Mercury - sorry can't be bothered crunching the numbers for a 10" dot :-)

Joe

[N1]

Note the 8-year gap. A good article here:

http://articles.adsabs.harvard.edu//full/1971JBAA...81..114M/0000114.000.html

I note a half-degree separation from the Sun's centre for the 2020 event; that one will be close shave indeed. A Hα observation is still all but impossible. You're going to need a huge prominence. Or find a way to view the Corona - she'll be close enough to be seen against it. ;)

What makes these events so interesting to me is the fact that the usual crescent phase changes into a very obvious annular phase. There appear to be few accounts from people who have actually seen it so I consider myself extremely lucky to be one of them (7 June 2012, 1.5° separation between the centres of the discs). It is a stunning sight and one of the best views I have ever had, of any target, through any telescope.

I'll hazard a guess that the next close one after 2028 won't happen until 2036.

[N1]

Here ya go. Courtesy of Calsky (http://www.calsky.com)

Some fun facts can be derived from it (I used the quick pdf search function):

- It appears separations during "good" inferior conjunctions will increase to about 2 degrees until about halfway between the last Transit pair and the next one (May 2068), then decrease until the next actual Transit. That kinda makes sense even without much thinking about it.

- From that halfway point onwards, it's the December pairs (separated 8 years) that make the closer approaches (Decembers 2069 and 2077 being the first one)

- The 2020 event (given here at 29.2 arc minutes) is the closest inferior conjunction until - wait for it - the next Transit of Venus in 2117. The December 2109 conjunction comes close at 36.8', but not quite..)

- After this year, it's less than 100 years until the next Transit of Venus

[Tinderboxsky]

I have put the dates in my diary. 🤞😄

[N1]

Same excercise for Mercury. The next conjunctions to watch (besides proper Transits, which are more frequent than Venus ones) are:

5 November 2026 at 22.4' separation
13 May 2029 at 23.2'
4 May 2036 at 25.7'
and
7 November 2039 at 13.9'

(assuming a solar radius being about 16' so the closer to that the better)

That last one should be pretty cool as it's an actual Transit happening really close to the limb. Shallow angles like that benefit most from H alpha observing, as they can be extended more than steep angle events, relatively speaking.

Edit: Hα observation with very large prominences that happen to be in the right place at the right time (extremely unlilkely), will really be the only way to see any of these conjunctions except for the 2039 event as Mercury has no brilliant atmosphere that could make it visible this close to the Sun. I'm guessing Mercury has to be several degrees out from the Sun to be visible at all.

[Tropo-Bob]

Thanks for the info guys. I do not know how U found it, but it saved me a lot of brain-strain. :thanx: