From a story in today's news:

Now, after more than a century, another Lowell observation that has been even more controversial -- the wheel-like "spokes" radiating from a "hub" on Venus -- has finally been explained.

With his 24-inch telescope in the Lowell Observatory, which he founded near Flagstaff, Ariz., in 1894, Lowell spent 15 years viewing Mars and sketching what he perceived as a network of fine lines connecting the polar cap with a number of dark areas.

Full story and explanation at http://www.chron.com/cs/CDA/story.hts/space/1568093

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I'd like to be able to do that. How far would I have to go with my ETX?

Pardon my cynicism, but isn't the picture on the right a shot of a human retina.

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Señor,

That's exactly what it is. Read the article linked above... it's interesting.

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The NY Times also has article about this (registration required). And overrated is right, it is interesting.

My server finally allowed me to read the article, and yes, extremely interesting.
So, what Lowell was actually sketching was his own retina. No wonder nobody else could reproduce the same image.
The previous theory went along the lines that the brain fills in the gaps that the eye can't resolve. Like trying to read a page from across the room, just a bunch of grey lines. Like the letters in a sentence, the craters and volcanoes just on the edge of visibility (at that resolution) formed into lines by the brain.
Anyway, a picture is worth a thousand words.

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Well, I finally got around to checking out the links, and I just realized I hadn't been reading it correctly. This isn't an explanation for what he saw on Mars. It only explains spoke-like lines he saw on Venus. From the New York Times:

It also states that the reason he had the aperture set so small was because Venus was so bright.

Mars, on the other hand, would not need that, because it's a much dimmer object.

So we still don't know for sure what he was seeing when he saw lines on Mars. Could it be the same effect? Maybe, but it doesn't seem like it. For one thing, the Martian canals weren't always the same, unlike his Venus observations. Maybe we'll never know.

In any case, it sure is interesting.

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That is very interesting. Very interestng.

Thanks for the information.

ljbrs [img]/phpBB/images/smiles/icon_smile.gif[/img] [img]/phpBB/images/smiles/icon_smile.gif[/img]

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Maybe he switched eyes every so often. [img]/phpBB/images/smiles/icon_smile.gif[/img]

Perhaps that would make a good experiment for next year's Mars opposition. From what I recall, his first observations of the "canals" were made during a close opposition (I recall that snippet of info being included in the Mars Show we did in the Planetarium, which I heard probably about 100 times). If he normally viewed Venus in such a way that its light was intensified, perhaps he tried viewing Mars the same way. Next year someone could try something similar with a telescope approximately the same size as Lowell's, and see if Mars is bright enough to show the capillaries inside their own eyes.

I'm skeptical, (of course). Wouldn't any astronomer who spent half his life looking in telescopes have seen his eye reflected and recognized the difference? I've seen my eye reflect back in my lens and I knew what it was.

There's a different focus from something reflecting off a surface right next to your eye and something you are looking at through the eyepiece. Your brain knows when your eye is focused on a distant object and a near one, even when the difference is small. The mirror in the eyepiece and the surface of the eyepiece are far enough apart that you would know what you were looking at. Even if your retina was reflecting on the lens surface, you'd know it wasn't at the same distance as the planet focused on the mirror and it just wouldn't look superimposed.

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I don't think the optometrists and ophthalmologists were saying that Lowell saw the reflection of his eye--instead, he saw the shadows of his blood vessels. This webpage seems to have some more background.

But the retinal image of capillaries that you see is not a reflection off the lens--it really does look like part of what you are looking at. I have experienced this myself when performing on stage with a large spotlight focused on me. It looked as if a giant net had been dropped down between me and the audience (and it certainly was not a reflected image--there was nothing there to reflect anything). If the light is not as intense, the capillaries will be fainter and the brain interprets them as part of the viewed scene.

But don't take my word for it--I'm suggesting it might be possible to find out if this is what Lowell saw by experimentation. Someone mentioned that Mars would not be bright enough to cause this, but at opposition and with a large enough telescope, it might be.

I also have a few loose brain cells that are reminding me that I once read something (probably in Sky and Telescope) about Lowell having some sort of eye disease. I know it was substantial enough for me to have mentioned it a couple of times during Planetarium shows, but it has since faded from my memory.

You could wait until August, when Mars is next at opposition, but why not go out in the early morning on December 6th? Mars will only be magnitude 1.7, but if you point your telescope at it, you'll only be 1 1/2 degrees from Venus--which will be mag. -4.7. Venus is the object that the article was about, too.