Beginners Question

Why are the images on most telescopes shown upside down, and can you buy an
adaptor to right them?

Steve wrote:
Why are the images on most telescopes shown upside down, and can you buy an
adaptor to right them?


It only matters if you are looking at terrestrial views. What is "upside
down" to an object in space ?

Steve

Its just that if I am looking at a diagram in an astronomy magazine showing
the positions of Saturn's or Jupiter's moons, is it showing it upside down?

Steve wrote:

Its just that if I am looking at a diagram in an astronomy magazine showing
the positions of Saturn's or Jupiter's moons, is it showing it upside down?

It depends on whether you're reading the magazine here or in Australia.

FoFP

"Steve" wrote in message
...
Why are the images on most telescopes shown upside down, and can you buy
an
adaptor to right them?

Yes, you can get an adapter to correct the image. Look for "image
rectifiers", "porro prism" or "amici prism". I've never used them myself, so
can't comment on them other than most astronomers like to use as few optical
lenses as possible to reduce light loss/image degradation.

About 4% of light is simply reflected back from your average piece of glass
(ie uncoated) so the more uncoated surfaces there are the more light there
is bouncing around in your optical train - sometimes bad enough to cause
double images in the eyepiece.

These rectifiers can turn your nighttime scope into a daytime "terrestrial"
scope and in the daytime there's plenty of light about, so loosing 4% or so
doesn't make any difference. At night time every little helps.

Regards,
Ed.

"Steve" wrote in message
...
Its just that if I am looking at a diagram in an astronomy magazine
showing
the positions of Saturn's or Jupiter's moons, is it showing it upside
down?



If the diagram says West is on the left side, then if you are in the
northern hemisphere it is shown upside down to correspond to the view
through an astronomical telescope.

Thanks Mike


"Mike Dworetsky" wrote in message
...


"Steve" wrote in message
...
Its just that if I am looking at a diagram in an astronomy magazine
showing
the positions of Saturn's or Jupiter's moons, is it showing it upside
down?



If the diagram says West is on the left side, then if you are in the
northern hemisphere it is shown upside down to correspond to the view
through an astronomical telescope.