Thursday, December 29, 2005

Naked Eye Attempt: Crescent Venus


Click image for U.S. Naval Observatory's ‘Apparent Disk of Solar System Object’. The image was created for the time of the sighting. Click here for a full list of ‘Data Services’ from the USNO.

On Tuesday (27-Dec) during lunch break I attempted to see if Venus' crescent would be visible naked eye. It's close to 55 arc seconds across! A few minutes were spent searching. It was found but it was a few degrees higher than expected. This goes to show how critical it is to be looking in the right spot.

Seeing Venus in full daylight is not as difficult as you would think. My latest sightings were made as Venus transited the meridian (azimuth = 180° — due south). Viewing Venus when it is at its highest point during the day may make or break sighting the crescent.

The attempt was made around 1:40pm. The crescent was not spotted and I would like to meet the person that can distinguish Venus' crescent naked eye. This would seem to require a rare level of visual acuity or one may need to view Venus when it is higher than a mere 30+ degrees above the horizon. This would place the planet above the haze.

Click the image below to view a chart of the Pleiades along with a depiction of the relative size of Venus compared to the distance of Pleiades members Pleione and Atlas — separation 5'04" (304 arc seconds). This distance is equivalent to stacking Venus five and a half times end to end. With Venus at nearly 55 arc seconds this works out to ~302 arc seconds.