Space Forum / Space Science / December 2008

Maybe the partial magnetic occlusion of Jupiter, by inclined Venus,
will provide an interesting observation for any properly configured
detection devices.

kk

-> Maybe the partial magnetic occlusion of Jupiter, by inclined Venus,
 
Huh?
 
                        dow

Whatever you silly folks do, might as well not bother taking any
pictures of our moon along with other planets, because according to
everything NASA/Apollo that’s just technically impossible, especially
if you and your unfiltered camera were situated upon our physically
dark Selene/noon..

We're told that not even with far better than film dynamic range (such
as the HDTV via JAXA) simply can not possibly include the solar
illuminated Selene/moon along with anything else other than Earth.
Therefore, pay no attention to all the others as having obtained such
pictures of our physically dark Selene/moon and other planets in the
same FOV.

How about we play God, and bring that big and bright looking moon down
to the same dot size of Venus, whereas lo and behold, there's no
contest as to which one has the greater albedo.

Even a 100% coal and carbon lampblack dusted surface the size and area
of Selene might be nearly as bright as viewed from Earth.  However, I
wonder how bright that terrain is while walking on that physically
dark surface, and especially if using a polarized optical filter?

BTW,  I’ve got lots of other examples of our physically dark but
otherwise perfectly solar illuminated Selene/moon along with the likes
of Jupiter or Saturn, and perhaps ten fold more of those including
Venus.  Of course these were all terrestrial obtained and thus had the
optical and dynamic range benefits of having to look through our
polluted atmosphere, that which must have nicely filtered and thereby
done the trick that anything via NASA/Apollo simply couldn’t muster.

~ Brad Guth Brad_Guth Brad.Guth BradGuth BG / “Guth Usenet”

-> Think about the geometry of the situation -- the directions pointing
-> away from the sun from Venus and from Jupiter ought to be rather close
-> to perpendicular to each other when they are in conjunction as seen
-> from Earth.
 
That depends on where the planets are on their orbits. Suppose, for
example, that they are both close to (superior) conjunction with the
sun as seen from the earth. Obviously, they will also be in
conjunction with each other. But the directions pointing away from the
sun from Venus and Jupiter would be pretty well parallel. Almost the
same line, in fact.
 
Bus suppose Jupiter is close to superior conjunction with the sun and
Venus to *inferior* conjunction, as seen from the earth. In this case,
the two directions away from the sun from Jupiter and Venus would be
pretty well in opposite directions, 180 degrees from each other.
 
Any intermediate angle is also possible. The two directions can be
anywhere from zero to 180 degrees apart.
 
In the case of the conjunction that happened a few days ago, Venus and
Jupiter were both further from the earth than the sun is, but not close
to superior conjunction. I'd guess that the angle between the two
directions from the sun past the two planets was something like 40
degrees.
 
                         dow

-> On Dec 8, 11:39 pm, david.willi...@bayman.org (David Williams) wrote:
-> > That depends on where the planets are on their orbits.

-> Agreed.  I was already implicitly taking into account their position
-> relative to the sun as seen in the earth's sky, which rules out the
-> almost-parallel cases.
 
How is their position relevant to the sun significant in determining
when a Venus-Jupiter conjunction occurs? Venus can be at any angle of
up to about 46 degrees relative to the sun in our sky, and a
conjunction with Jupiter can occur if Jupiter is within that 92-degree
arc. The directions from the sun past the two planets will be
perpendicular, as you said, only if Venus is a bit closer to the earth
than it is at maximum elongation, which certainly was not the case
during the recent conjunction.
 
                          dow

-> Will there ever -- or have there ever -- been Venusian transits across
-> the sun, from the perspective of Jupiter?
 
Certainly. They must occur quite often. The orbital plane of Venus is
inclined a few degrees relative to that of Jupiter. But if Venus
happens to be close to one of the crossing points, where the two planes
intersect, at the same time as Jupiter is in the same direction as seen
from the sun, then an observer on (or near) Jupiter would see Venus
transiting the sun's disk.
 
                         dow