Subject: Venus Pix
From: adamod <[email-masked]>
Date: Fri, 20 Mar 2009 17:14:06 -0500

ATIG Members-

As illustrated in the attached GIF's J2000.0 ecliptic plane plot of Earth
and Venus motion about the Sun, a line of sight from Earth to the Sun is in
the +X direction today, and Spring is here.  This line also passes very
close to Venus, making it dangerous for me to continue taking daytime images
of our sister planet without frying my telescope's optics.  Venus will "lap"
Earth (in the heliocentric sense) on March 24, an event known as inferior
conjunction.

The attached JPEG is a montage of 4 daytime Venus images obtained at an
effective magnification of 62x during the GIF plot's time span.  Each image
is cropped to 615 px in horizontal dimension and 397 px in vertical
dimension to maintain a consistent scale illustrating progressively smaller
Venus geocentric distance during the sequence.  To state image scale in more
absolute terms, Venus apparent angular diameter in the March 20 image is 58
arc-sec, approaching resolution capability of the unaided human eye.  Of
course, don't even think about looking for Venus in the daytime with a line
of sight this close to the Sun!

Each image in the JPEG is oriented with celestial north upward to
demonstrate rotation of the Venus morning terminator as its phase evolves
from "quarter Moon" to crescent.  The "horns" of this crescent clearly
become biased in a northerly direction as inferior conjunction approaches.
This is because Venus lies more than 3 deg north of the ecliptic plane on
March 20.  Currently, the orbit of Venus has a descending node on the
ecliptic at a heliocentric longitude occupied by Earth in early June each
year.  In 2012, Venus descending nodal passage will occur near enough to
inferior conjunction to produce a transit of Venus across the Sun as
observed from Earth.

If the attached files won't download in your copy of Outlook, they will in
NASA WebMail.

-Dan