Stupid Observing Trick

David Copperfield (the illusionist, *not* the Charles Dickens character)
is known for such stunts as making the Statue of Liberty disappear. You
can upstage him for a short while this week: The solar system's most
massive planet, Jupiter, can be made to vanish with a mere -- though
measuredly deliberate -- glance of your eye!

Here's how to do it:

1. Over the next couple days, step outside during late dusk or early
evening; locate Venus and Jupiter, both gleaming low in the
western sky.

2. Stare directly at Venus, then tilt your head so that an imaginary
line connecting your eyes is roughly parallel with a line defined
by Venus and Jupiter.

3. Now utter the magic incantation: "Oh, great Jove, swirling orb of
hydrogen and methane -- begone!" (If pinched for time, this step
may be skipped with no loss of effectiveness, though you won't earn
as many style points...)

4. Cover (or close) your *right* eye. Poof! -- Jupiter will disappear
from your left eye's field of view, so long as your gaze stays
fixed on Venus and your head maintains the required tilt.


This trick is nothing more than a celestial analog of the ol' two-dots-
on-paper blind-spot demonstration, of course. The fovea (the central
region of the retina) and blind spot are some 17 degrees apart. Likewise
the separation of Venus and Jupiter for a short spell early this week,
hence the stunt's restricted time period.

I've wondered whether there might be a practical observational use for
knowing the location of my blind spot. For instance, when trying to
detect a faint fuzzy in my telescope's field of view, which happens also
to contain an annoyingly bright and distracting star, might it be feasible
to fudge the magnification, the centering, or my head's orientation to
position that bright star onto my blind spot, effectively squelching it
from view?

Then again, perhaps the reason why this idea hasn't been exploited is
because of a far simpler alternative: If you've got an annoyingly bright
star in the field of view, then move the telescope a smidgen to position
that offending star just outside the FoV!

--
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
Mark Gingrich San Leandro, California

Good post Mark! I've done this with Jupiter in the past by just finding=20
a star the right distance away. Clever to have noticed that Venus is the =

correct distance away. I suppose you could also make Venus vanish if you =

covered your left eye. ;-)

-Florian

Florian wrote:

I suppose you could also make Venus vanish if you covered your
left eye. ;-)

Yes, that also works, but I think causing the more massive -- by a
factor of nearly 400 -- planet to vanish is a flashier stunt.

And once you've mastered the art of making planets disappear, you can
then test your prowess on still larger objects -- stars. Two meeting the
angular-separation criterion are Sirius and 2nd-magnitude Saiph. (Saiph
being Kappa Orionis, the hunter's right kneecap; I unabashedly suggest
the name "knee-kappa" as a corny mnemonic aid...)

Step 1. With both Sirius and Orion well above the horizon, tilt your
head so that a line connecting your eyes is roughly parallel
with the line between Sirius and Kappa Orionis.

Step 2. Now stare intently at Kappa.

Step 3. To those well north of the equator (for whom Orion appears "right
side up"), cover your right eye; to observers well south of the
equator (for whom Orion appears "upside down"), cover your left
eye. Sirius will then vanish from view -- an averted view, mind
you -- so long as you maintain the proper head tilt and keep
fixated on Kappa.


At this time of year you must go out under the pre-dawn sky to view
Sirius and Kappa Orionis. However, the two don't shift their relative
positions noticeably over our lifetimes, which makes them a fine pair for
this stunt whenever fast-moving planets don't cut it, angular-wise.

--
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
Mark Gingrich San Leandro, California

While walking the dog this evening i made both Jupiter and Venus vanish! =

(Not at the same time of course.) I tried to make the moon vanish but=20
couldn't really. Just too big and bright.

-Florian

I tried to make the moon vanish but
couldn't really. Just too big and bright.

Try closing both eyes. The moon will vanish.

Neat idea Mark! I will use this with some kids. It will teach two ideas as
well as get them looking up.

Clear Skies

Chuck Taylor
Do you observe the moon?
Try http://groups.yahoo.com/group/lunar-observing/

To reply, remove Delete and change period com to period net
************************************************** ************


"Mark Gingrich" wrote in message
...

David Copperfield (the illusionist, *not* the Charles Dickens character)
is known for such stunts as making the Statue of Liberty disappear. You
can upstage him for a short while this week: The solar system's most
massive planet, Jupiter, can be made to vanish with a mere -- though
measuredly deliberate -- glance of your eye!

Here's how to do it:

1. Over the next couple days, step outside during late dusk or early
evening; locate Venus and Jupiter, both gleaming low in the
western sky.

2. Stare directly at Venus, then tilt your head so that an imaginary
line connecting your eyes is roughly parallel with a line defined
by Venus and Jupiter.

3. Now utter the magic incantation: "Oh, great Jove, swirling orb of
hydrogen and methane -- begone!" (If pinched for time, this step
may be skipped with no loss of effectiveness, though you won't earn
as many style points...)

4. Cover (or close) your *right* eye. Poof! -- Jupiter will disappear
from your left eye's field of view, so long as your gaze stays
fixed on Venus and your head maintains the required tilt.


This trick is nothing more than a celestial analog of the ol' two-dots-
on-paper blind-spot demonstration, of course. The fovea (the central
region of the retina) and blind spot are some 17 degrees apart. Likewise
the separation of Venus and Jupiter for a short spell early this week,
hence the stunt's restricted time period.

I've wondered whether there might be a practical observational use for
knowing the location of my blind spot. For instance, when trying to
detect a faint fuzzy in my telescope's field of view, which happens also
to contain an annoyingly bright and distracting star, might it be feasible
to fudge the magnification, the centering, or my head's orientation to
position that bright star onto my blind spot, effectively squelching it
from view?

Then again, perhaps the reason why this idea hasn't been exploited is
because of a far simpler alternative: If you've got an annoyingly bright
star in the field of view, then move the telescope a smidgen to position
that offending star just outside the FoV!

--
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
Mark Gingrich San Leandro, California

Does it work if the other eye is dominatnt.?

D
"Mark Gingrich" wrote in message
...

David Copperfield (the illusionist, *not* the Charles Dickens character)
is known for such stunts as making the Statue of Liberty disappear. You
can upstage him for a short while this week: The solar system's most
massive planet, Jupiter, can be made to vanish with a mere -- though
measuredly deliberate -- glance of your eye!

Here's how to do it:

1. Over the next couple days, step outside during late dusk or early
evening; locate Venus and Jupiter, both gleaming low in the
western sky.

2. Stare directly at Venus, then tilt your head so that an imaginary
line connecting your eyes is roughly parallel with a line defined
by Venus and Jupiter.

3. Now utter the magic incantation: "Oh, great Jove, swirling orb of
hydrogen and methane -- begone!" (If pinched for time, this step
may be skipped with no loss of effectiveness, though you won't earn
as many style points...)

4. Cover (or close) your *right* eye. Poof! -- Jupiter will disappear
from your left eye's field of view, so long as your gaze stays
fixed on Venus and your head maintains the required tilt.


This trick is nothing more than a celestial analog of the ol' two-dots-
on-paper blind-spot demonstration, of course. The fovea (the central
region of the retina) and blind spot are some 17 degrees apart. Likewise
the separation of Venus and Jupiter for a short spell early this week,
hence the stunt's restricted time period.

I've wondered whether there might be a practical observational use for
knowing the location of my blind spot. For instance, when trying to
detect a faint fuzzy in my telescope's field of view, which happens also
to contain an annoyingly bright and distracting star, might it be feasible
to fudge the magnification, the centering, or my head's orientation to
position that bright star onto my blind spot, effectively squelching it
from view?

Then again, perhaps the reason why this idea hasn't been exploited is
because of a far simpler alternative: If you've got an annoyingly bright
star in the field of view, then move the telescope a smidgen to position
that offending star just outside the FoV!

--
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
Mark Gingrich San Leandro, California

"david" asked:

Does it work if the other eye is dominatnt.?


Yes, it does. I have a dominant right eye, yet I can perform an
"eye-clipse" of Sirius by staring at Kappa Orionis with just my
left eye.

--
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
Mark Gingrich San Leandro, California

I can do this trick without all that hassle - it's called cloud :-)

Regards

Colin Dawson.

"david" wrote in message
...
Does it work if the other eye is dominatnt.?

D
"Mark Gingrich" wrote in message
...

David Copperfield (the illusionist, *not* the Charles Dickens character)
is known for such stunts as making the Statue of Liberty disappear. You
can upstage him for a short while this week: The solar system's most
massive planet, Jupiter, can be made to vanish with a mere -- though
measuredly deliberate -- glance of your eye!

Here's how to do it:

1. Over the next couple days, step outside during late dusk or early
evening; locate Venus and Jupiter, both gleaming low in the
western sky.

2. Stare directly at Venus, then tilt your head so that an imaginary
line connecting your eyes is roughly parallel with a line defined
by Venus and Jupiter.

3. Now utter the magic incantation: "Oh, great Jove, swirling orb of
hydrogen and methane -- begone!" (If pinched for time, this step
may be skipped with no loss of effectiveness, though you won't earn
as many style points...)

4. Cover (or close) your *right* eye. Poof! -- Jupiter will disappear
from your left eye's field of view, so long as your gaze stays
fixed on Venus and your head maintains the required tilt.


This trick is nothing more than a celestial analog of the ol' two-dots-
on-paper blind-spot demonstration, of course. The fovea (the central
region of the retina) and blind spot are some 17 degrees apart. Likewise
the separation of Venus and Jupiter for a short spell early this week,
hence the stunt's restricted time period.

I've wondered whether there might be a practical observational use for
knowing the location of my blind spot. For instance, when trying to
detect a faint fuzzy in my telescope's field of view, which happens also
to contain an annoyingly bright and distracting star, might it be
feasible
to fudge the magnification, the centering, or my head's orientation to
position that bright star onto my blind spot, effectively squelching it
from view?

Then again, perhaps the reason why this idea hasn't been exploited is
because of a far simpler alternative: If you've got an annoyingly bright
star in the field of view, then move the telescope a smidgen to position
that offending star just outside the FoV!

--
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
Mark Gingrich San Leandro, California

I had a dog that could do this and not write about it!.


Mark Gingrich wrote:

David Copperfield (the illusionist, *not* the Charles Dickens character)
is known for such stunts as making the Statue of Liberty disappear. You
can upstage him for a short while this week: The solar system's most
massive planet, Jupiter, can be made to vanish with a mere -- though
measuredly deliberate -- glance of your eye!

Here's how to do it:

1. Over the next couple days, step outside during late dusk or early
evening; locate Venus and Jupiter, both gleaming low in the
western sky.

2. Stare directly at Venus, then tilt your head so that an imaginary
line connecting your eyes is roughly parallel with a line defined
by Venus and Jupiter.

3. Now utter the magic incantation: "Oh, great Jove, swirling orb of
hydrogen and methane -- begone!" (If pinched for time, this step
may be skipped with no loss of effectiveness, though you won't earn
as many style points...)

4. Cover (or close) your *right* eye. Poof! -- Jupiter will disappear
from your left eye's field of view, so long as your gaze stays
fixed on Venus and your head maintains the required tilt.

This trick is nothing more than a celestial analog of the ol' two-dots-
on-paper blind-spot demonstration, of course. The fovea (the central
region of the retina) and blind spot are some 17 degrees apart. Likewise
the separation of Venus and Jupiter for a short spell early this week,
hence the stunt's restricted time period.

I've wondered whether there might be a practical observational use for
knowing the location of my blind spot. For instance, when trying to
detect a faint fuzzy in my telescope's field of view, which happens also
to contain an annoyingly bright and distracting star, might it be feasible
to fudge the magnification, the centering, or my head's orientation to
position that bright star onto my blind spot, effectively squelching it
from view?

Then again, perhaps the reason why this idea hasn't been exploited is
because of a far simpler alternative: If you've got an annoyingly bright
star in the field of view, then move the telescope a smidgen to position
that offending star just outside the FoV!

--
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
Mark Gingrich San Leandro, California