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Date: 01 Sep 2007 19:01:22
From: mick
Subject: binoc advice
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Come on!...I can't imagine even tasco binocs not showing Jupiters first four
moons....
NJ Charlie wrote:
> I'm an old timer at astronomy but never have owned good binoculars. I've
> had a pair of 8x30s which were
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Date: 04 Sep 2007 13:24:07
From: palsing
Subject: Re: binoc advice
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On Sep 4, 6:28 am, Quadibloc <jsav...@ecn.ab.ca > wrote:
> mick wrote:
> > Come on!...I can't imagine even tasco binocs not showing Jupiters first four
> > moons....
>
> Since they're not visible to the naked eye, I can easily imagine even
> a high-quality pair of binoculars not showing them; all that is
> required is that the magnification not be particularly high.
When my kids were young, they could each see the moons of Jupiter
naked-eye, at least the moons near greatest elongation. We used to
make a game of it, they would tell me what they saw, and we would then
verify it telescopically. they were always right.
They could also see the phases of Venus naked eye. As they got older,
into their 20's, they could no longer perform these same observations.
So, I agree that even the cheapest binoculars should easily show the
moons of Jupiter.
\Paul
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Date: 05 Sep 2007 08:40:26
From: Dennis Woos
Subject: Re: binoc advice
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> When my kids were young, they could each see the moons of Jupiter
> naked-eye, at least the moons near greatest elongation. We used to
> make a game of it, they would tell me what they saw, and we would then
> verify it telescopically. they were always right.
>
Here is an interesting article on naked-eye observactons of the moons of
Jupiter that was published in Sky&Tel:
http://denisdutton.com/jupiter_moons.htm
Dennis
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Date: 04 Sep 2007 06:28:58
From: Quadibloc
Subject: Re: binoc advice
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mick wrote:
> Come on!...I can't imagine even tasco binocs not showing Jupiters first four
> moons....
Since they're not visible to the naked eye, I can easily imagine even
a high-quality pair of binoculars not showing them; all that is
required is that the magnification not be particularly high.
7x50 binoculars, for example, magnify only 7 times. But since the
aperture is seven times the 7mm diameter of the dark-adapted eye, they
give fully 49 times the light from stars; they qualify as a "richest-
field" optical device.
So, if that is enough to make the Galilean satellites visible, that
will happen. But if the aperture is smaller than 50mm, only, say,
35mm, then whatever the magnification, we will now only have 25 times
the light from stars as they give to the naked eye when dark adapted.
If that is not enough, the Galilean satellites will not be seen.
But I see that even Titan is magnitude 8.5, and the Galilean
satellites are magnitude 5, visible to the naked eye, even, if not for
the glare of Jupiter. So indeed they ought to be visible through just
about *any* kind of optical aid, and you are basically right.
Of course, one could imagine such bad seeing, or such light-polluted
skies, as to render them harder to see...
John Savard
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Date: 01 Sep 2007 20:28:04
From: Steve Pearce
Subject: Re: binoc advice
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On Sat, 01 Sep 2007 19:01:22 GMT, "mick" <mik@commiecas.org > wrote:
>Come on!...I can't imagine even tasco binocs not showing Jupiters first four
>moons....
So you keep saying...
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