Astronomy Online 1996

Österreichischer Astronomischer Verein
Vienna, Austria

Daylight observation of Venus

A common rule of thumb says that Venus is visible if the magnitude is -4.2 or brighter. This year (1996), I found that observing the planet Venus in bright daylight was not as difficult as I had always imagined before. I am shortsighted with about 3.5 dioptries, and I had thought it was immensely difficult to focus into a plain blue sky. I could find the tiny dot of Venus a few times in spring in the afternoon, when Venus was the Evening Star. I found it with 10x50 binoculars and then with my eyeglasses on, and it was not at all difficult! A big help were some clouds nearby which helped focusing the eye.

After inferior conjunction, Venus reappeared as Morning Star. I once saw the planet rise in the morning and remembered a sentence read long ago about her shining so bright that a shadow is easily seen, and - I saw it! My attention grew bigger and in mid-August 1996 I started to observe Venus in the daylight sky again. I found that it might be visible even when dimmer than mag -4.2, especially if the sky is clear and free of haze. And I could observe Venus a few times at the end of August, when the magnitude was down to -3.9! Unfortunately, this September was the worst in the history of weather statistics of Austria (since about 1880), so I could not observe more than once, around the 10th of September. Rapidly moving thick clouds made it impossible for me to keep my eyes focussed in cloud distance and fixed on the assumed location of the tiny dot, so I cannot confirm having really seen it. Just when I thought I had the right spot, the next cloud covered the blue. :-(

At last, the day after the lunar eclipse (Sept. 28., 1996) was clear again, but when I wanted to try, I saw it was no use, the sky was too misty then (carrying the remnants of the classical Great Fog Of Eclipse Night :-(. Monday, the 30th of September greeted with the first really friendly weather since August. And I saw that the sky was extremely dry and free of haze! I asked my calculator (see Urania/48) for azimuth, altitude and magnitude, grabbed my binoculars with solar filters and went into the garden. I focussed on the Sun, then removed the filters and searched the sky where Venus should be... no, was - perfect! Right then, a small thin cloud passed Venus, and I put down the binoculars and focussed my eyes into this cloud. YES! There it was! And it was still easy!

So, I can tell you: I have seen Venus on the 30th of Septenber, 1996, with a magnitude of -3.6 (calculated), in elongation 41.8 degrees. I think, if the sky is clear enough, Venus might be still observable with a magnitude of -3.4 and elongation of 30 degrees or so.

Update Nov.2nd, 1996:

Today, the sky was again clear enough with some clouds, and also today I could see Venus with just my eyeglasses on, at mag -3.5, in 35.5 degrees eastern elongation.

Update Dec.4th, 1996:

Even today, with Venus at mag. -3.4 and elongation of 28.5°, I could identify the small point with my naked eye after finding it with my 10x50 binoculars. Admittedly, it was very hard to see. Weather forecast is bad, so this could have been the last opportunity at this apparition.

If you want to try the same, there is only so little to remember.

If you can find Venus or have similar or even more experience, please email me at the address given below.

Good Luck!

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© Georg ZOTTI, 1996 - 11 - 02