Saturday, December 10, 2005

Venus' Phase Naked Eye?


Yesterday (9-Dec) I went to Bryant Park (near the New York Public Library) after a ‘half-day Friday’ at the office, to spot Venus naked eye after the storm. Blue skies predominated.

I've kept notes on the location of various azimuths (locations along the horizon in degrees) from my personal Uraniborg around the Bryant Park lawn so I knew approximately where to look for the planet. After searching for about a minute I spotted Venus fairly easily. Easier than usual for some reason. It was steadily seen and easily recovered when I looked back after taking notes.

The planet was spotted as it was southing (crossing the meridian) so it was considerably higher than the Sun.

Screen Shots from Planetarium for the Palm

PftP_Venus_20051209_Pos_320p.bmp PftP_Venus_20051209_Stats_320p.bmp

I remember reading about seeing Venus' crescent naked eye only after viewing the planet. All I've ever remembered was that Venus appeared starlike but I never thought to check out if the crescent were visible.

Below are a few articles from ‘The NASA Astrophysics Data System’ on seeing the phase of Venus naked eye. These appear to be some of the first published reports of sighting the crescent naked eye.

One of the articles mentions that when Venus is 40 arc seconds it is equivalent to seeing a 1" object approximately 430 feet away. If you've seen this could you let us know when this happened and the circumstances surrounding the sighting?

Is the Crescent Form of Venus Visible to the Naked Eye?’ by Campbell, W. W. (Apr./1916)
Publ. of the Astronomical Society of the Pacific, Vol. 28, No. 163, p.86
Notes & Queries: Phase of Venus seen w/the Naked Eye’ by Chant, C. A. (Jan./1929)
Journal of the Royal Astronomical Society of Canada, Vol. 23, p.48
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Notes & Queries: Crescent Venus seen w/the Naked Eye’ by Chant, C. A. (Mar./1929)
Journal of the Royal Astronomical Society of Canada, Vol. 23, p.144
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Notes & Queries: Venus as a Crescent w/the Naked Eye’ by Chant, C. A. (Jan./1935)
Journal of the Royal Astronomical Society of Canada, Vol. 29, p.30
>>> Scroll to page 31:
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Other references to phase sightings of Venus naked eye:

Inferential Evidence for the Pre-telescopic Sighting of the Crescent Venus’ by David Lance Goines
(Berkeley, California, 1992; version of Oct. 18, 1995)

Naked-eye detection of the phase of Venus
By Jay Reynolds Freeman (28 May 1996)

Web Searches:

Wikipedia: Phases of Venus
Usenet '*astro*' [405]: venus crescent naked-eye
Google [260]: venus-crescent or crescent-venus naked-eye
NASA ADS Search [4]: venus and crescent and 'naked eye'

Image from ‘New York Public Library: N.Y. Architecture Images - Midtown’


Kim said...

That's an interesting experiment. In theory, if Jupiter's disk weren't so bright, you could see the four Galilean moons naked eye also.

Ben C. said...


True about the Galilean satellites. When I was first starting out in astronomy I observed with a few of my fellow teenage friends and their younger brothers. There was one day where one of the younger ones asked if the moons of Jupiter were aligned in a certain way. I asked whey and he told me he could could see something close to Jupiter. He was describing the orientation of the plane of the moons without using optical aid. At the time I was observing with a 6" reflector so the image in the scope would not have matched his description. I haven't read much about seeing this but since I couldn't *prove* it I wrote it off as something to keep an eye out for in the literature.

Today I tried for Venus again at Bryant park around 2:30p but the clouds were hugging the horizon a bit too tightly.

All the best.


P.S. - glad to see you are into both astronomy and birding. They go well together.