Today is the 400th Anniversary of Galileo Discovering Ganymede

The other three Galilean moons of Jupiter - Io, Callisto and Europa -
he discoverd last Friday (400 years ago).

Let's go!

http://1mmph.yolasite.com/

On Jan 12, 9:36*pm, giveitawhirl2008
wrote:
The other three Galilean moons of Jupiter - Io, Callisto and Europa -
he discoverd last Friday (400 years ago).

Let's go!

http://1mmph.yolasite.com/

The amazing thing is that he used a telescope that had less
magnification (20x) and smaller aperture than a cheap chinese $10 set
of chinese binoculars.
www.wwnorton.com/.../images/18thc/telescope.jp

No wonder he had red-rimmed eys:
http://en.wikipedia.org/wiki/File:Ga...arp.300pix.jpg

"Pat Flannery" wrote in message
. ..
lorad wrote:
The amazing thing is that he used a telescope that had less
magnification (20x) and smaller aperture than a cheap chinese $10 set
of chinese binoculars.

Most binoculars have either 7X or 10X magnification; but the four moons of
Jupiter are visible through both magnifications.
Heck, I saw them once with my naked eye on a very clear, cold, and still
night by positioning myself so that Jupiter itself was occulted by a thin
twig on a tree around fifty feet from me.
All four have enough magnitude to be naked-eye visible, it's just that the
glare of Jupiter itself hides them from view.
My favorite was Galileo trying to figure out why Saturn looked so odd
through his telescope:
http://galileo.rice.edu/sci/observations/saturn.html



Pat
http://galileo.rice.edu/images/thing...ns_phases1.gif
Now why would the name "Huygens" be in that URL?
http://galileo.rice.edu/images/thing...ius_phases.gif
Now why would the name "Hevelius" be in that URL?

My favourite was Flannery trying to figure out why Galileo looked so
Huygens through his URL.

lorad wrote:
The amazing thing is that he used a telescope that had less
magnification (20x) and smaller aperture than a cheap chinese $10 set
of chinese binoculars.

Most binoculars have either 7X or 10X magnification; but the four moons
of Jupiter are visible through both magnifications.
Heck, I saw them once with my naked eye on a very clear, cold, and still
night by positioning myself so that Jupiter itself was occulted by a
thin twig on a tree around fifty feet from me.
All four have enough magnitude to be naked-eye visible, it's just that
the glare of Jupiter itself hides them from view.
My favorite was Galileo trying to figure out why Saturn looked so odd
through his telescope: http://galileo.rice.edu/sci/observations/saturn.html



Pat

"Pat Flannery" wrote in message
. ..
lorad wrote:
The amazing thing is that he used a telescope that had less
magnification (20x) and smaller aperture than a cheap chinese $10 set
of chinese binoculars.

Most binoculars have either 7X or 10X magnification; but the four moons of
Jupiter are visible through both magnifications.

I still recall the firs time I saw the moons of Jupiter. I used a pare of
binoculars.

VERY cool.

Heck, I saw them once with my naked eye on a very clear, cold, and still
night by positioning myself so that Jupiter itself was occulted by a thin
twig on a tree around fifty feet from me.
All four have enough magnitude to be naked-eye visible, it's just that the
glare of Jupiter itself hides them from view.
My favorite was Galileo trying to figure out why Saturn looked so odd
through his telescope:
http://galileo.rice.edu/sci/observations/saturn.html



Pat



--
Greg Moore
Ask me about lily, an RPI based CMC.

Pat Flannery wrote in
:

lorad wrote:
The amazing thing is that he used a telescope that had less
magnification (20x) and smaller aperture than a cheap chinese $10 set
of chinese binoculars.

Most binoculars have either 7X or 10X magnification; but the four
moons of Jupiter are visible through both magnifications.
Heck, I saw them once with my naked eye on a very clear, cold, and
still night by positioning myself so that Jupiter itself was occulted
by a thin twig on a tree around fifty feet from me.

You need pretty acute vision to see it though.

"Pat Flannery" wrote in message
...
Greg D. Moore (Strider) wrote:

I still recall the firs time I saw the moons of Jupiter. I used a pare of
binoculars.

VERY cool.

Jupiter, the Moon, and Saturn are about the three most fun objects to look
at with a small telescope.
What amazed me was how fast the moons rotate around Jupiter, so that their
positions noticeably change in just a few hours.
At one time it was proposed that telescopic observations of them could be
used to determine a ship's longitude without carrying a chronometer by
carefully determining their positions relative to the planet and each
other and comparing that to drawings in a book that would show at what
exact time a certain alignment would occur.
Unfortunately, the pitching of the ship in the waves made the idea
impractical in a pre-gyro-stabilized era.

Pat

Good grief! A remote clock that anyone can see from anywhere!
Doesn't that upset the "genius" Einstein's time dilation?

"If we assume that the result proved for a polygonal line is also valid for
a continuously curved line, we arrive at this result: If one of two
synchronous clocks at A is moved in a closed curve with constant velocity
until it returns to A, the journey lasting t seconds, then by the clock
which has remained at rest the travelled clock on its arrival at A will be
1/2 tv^2/c^2 second slow. Thence we conclude that a balance-clock at the
equator must go more slowly, by a very small amount, than a precisely
similar clock situated at one of the poles under otherwise identical
conditions." -- Albert ****wit Einstein.

Greg D. Moore (Strider) wrote:

I still recall the firs time I saw the moons of Jupiter. I used a pare of
binoculars.

VERY cool.

Jupiter, the Moon, and Saturn are about the three most fun objects to
look at with a small telescope.
What amazed me was how fast the moons rotate around Jupiter, so that
their positions noticeably change in just a few hours.
At one time it was proposed that telescopic observations of them could
be used to determine a ship's longitude without carrying a chronometer
by carefully determining their positions relative to the planet and each
other and comparing that to drawings in a book that would show at what
exact time a certain alignment would occur.
Unfortunately, the pitching of the ship in the waves made the idea
impractical in a pre-gyro-stabilized era.

Pat

Rich wrote:

You need pretty acute vision to see it though.

Although I tried it on several occasions (I read about the trick in a
book) it only worked once on a incredibly cold and still winter night
after a powerful cold front had gone through.
Those kind of conditions sometimes allowed up to nine stars to be
visible in the Pleiades if your eyes were dark-adapted enough.
That would usually occur around the time the frostbite was beginning to
set in. :-)

Pat

"Greg D. Moore (Strider)" wrote in message
m...
"Pat Flannery" wrote in message
. ..
lorad wrote:
The amazing thing is that he used a telescope that had less
magnification (20x) and smaller aperture than a cheap chinese $10 set
of chinese binoculars.

Most binoculars have either 7X or 10X magnification; but the four moons of
Jupiter are visible through both magnifications.

I still recall the firs time I saw the moons of Jupiter. I used a pare of
binoculars.

VERY cool.


One of the best memories of my old Meade 10" scope was the first
time I saw IO emerge from behind Jupiter.


Heck, I saw them once with my naked eye on a very clear, cold, and still
night by positioning myself so that Jupiter itself was occulted by a thin
twig on a tree around fifty feet from me.
All four have enough magnitude to be naked-eye visible, it's just that the
glare of Jupiter itself hides them from view.
My favorite was Galileo trying to figure out why Saturn looked so odd through
his telescope:



A fuzzy image makes Saturn look like a planet with 'ears'.



http://galileo.rice.edu/sci/observations/saturn.html



Pat



--
Greg Moore
Ask me about lily, an RPI based CMC.