Astronomy

This image taken at about 18:24 Arizona time, is the approximate mid point in the transit of Venus. I adjusted the image such that ecliptic north is up. Venus moved from left to right across the northern hemisphere of the solar disc.

Image: Venus at Mid-Transit. Camera: Canon SX-40, Rainbow Symphony Solar Filter, Shutter Speed: 1/2000′, Aperture: F 5.0, Film Speed: ISO 3200

We will not be able to watch or photograph much more today since the terrain rises to the west and apparent sunset is about forty minutes before actual. Regardless, we wouldn’t see Venus exit the disc since that will occur well after sundown here in the 48 contiguous states. We feel lucky that we got to see the midpoint of the transit.

We also feel lucky to have witnessed two solar events in just a little over three weeks, the first semi-rare event being the annular eclipse and this extremely rare Venus transit. The next transit of Venus will be 105 years hence in the year 2117.

Sebastian posted a bleg yesterday asking about observing the 2012 transit of Venus across the solar disk.Since I have been preparing for the annular eclipse, I posted a comment there pointing to my recent experiences with solar photography. His post got me to look up some information about the transit since we wanted to observe it here, too.

I found the NASA map of global visibility (Image courtesy of NASA) Going to the link helps you to decode the map elements (I,II,III,IV). Click on the map to enlarge.

There is a listing of transit contact events for US cities (and another for international). The closest city listed to our location is Phoenix, AZ. The first event is when the disc of Venus first touches the solar disc occurs at 15:05:55 (Arizona Time); the sun will be 54° above the horizon. The second event is when the other edge of Venus crosses the edge of the sun and occurs at 15:23:32; the sun will be at 50° of elevation. The last transit contact listed is greatest transit which, I assume, is when Venus is halfway across its path over the sun; that occurs at 19:25:24 when the sun is at 13° of elevation.

Nobody in the 48 contiguous states can witness the entire transit because it will not be over until after sundown. It will be entirely visible in Alaska and Hawaii, however.

So, I guess we will keep the eclipse shades and solar filters handy for another three weeks or so. We wouldn’t want to miss this transit since the next one will not be until December of 2117.