Rim of Emission around Venus
Please tell me cresent
phase of venus will visible
during second and third contact of venus transit though telescope?
Rajiv Srivastav
Rajiv, on the day of the
transit Venus will be in the New phase, analogous to the New Moon of an eclipse.
In the last week or so, of May, if at all you have a clear view of the horizon -
you could see Venus as a crescent. It will be continously decresing in phase all
the way from now of course, it is not far from full phase now.
You may also be referring to a rim of emission that is seen around Venus
at the time of transit, which could also be visible as a crescent depending on
the extent of immersion of Venus - this arises from the atmosphere of Venus -
and I suppose this should be visible - one would have to look for it halfway
between first and second contact, probably.
Rathnasree
Rajiv, I have been wondering about this rim of emission - in historical transits - there are
mentions of it in some places and times but, not all. What factors would its
visibility depend on? I am trying to compile together all historical mentions of
it and compare observing equipment used - I will post about what I do find.
Sorry, about my misunderstanding what you said.
Rathnasree
I read few articles on rim of emission in
historical venus transits, which
stared very bright few seconds before first contact with moving position
when it toches sceonds contact.
Rajiv Srivastav
This is described in the observations at Hudson Bay, by Wales and Dummond, in Philosophical Transactions, 1769, as follows -
"Soon after Venus was half immerged, a bright crescent or rim of light, encompassed all that part of her circumference which was off the Sun, thereby rendering her whole periphery visible. This continued very bright until within a few minutes of the internal contact, and then vanished away gradually."
There would be a connection, I suppose, between the Venus
atmospheric
contribution to the Black Drop and this bright rim that is usually seen.
Rathnasree
Compiled from the Venus Transit Group