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View Full Version : Why wasn't Uranus found earlier?



Nick Theodorakis
2009-Jan-22, 05:11 PM
Uranus has a very low visual magnitude, but should be naked-eye visible in a dark site to a keen observer. Why was it not recognized until Herschel? Too slow? Too dim?

Nick

Tucson_Tim
2009-Jan-22, 05:14 PM
At 6th magnitude, it is barely visible with the naked eye. Against the myriad of background stars, it would be very, very hard to see. It is hard to spot now, even when you know exactly where it is.

Tucson_Tim
2009-Jan-22, 05:34 PM
Too slow? Too dim?

Nick

I think you hit with these: too slow, too dim. It would be a sharp-eyed observer indeed that could spot Uranus's slow, dim movement.

I've tried to see Uranus with my naked eye and failed every time. I can see it with low-power binocs, but only because I have a star chart in front of me and I know exactly where it is.

aurora
2009-Jan-22, 05:36 PM
It was observed before Herschel. So I think your "too slow" guess is a good one. I think it was also not recognized because a new planet was just not imaginable.

http://en.wikipedia.org/wiki/Uranus


The earliest recorded sighting was in 1690 when John Flamsteed observed the planet at least six times, cataloging it as 34 Tauri.

Tucson_Tim
2009-Jan-22, 05:36 PM
Antoniseb might be able to spot it. He has those Chuck Yeager eyes! :)

(NOTE: In his autobiography, Chuck Yeager has stated that his "kills" during WWII were partly the result of his very keen eyesight - he saw the enemy planes before they saw him and was able to get into the best position for the attack.)

Nick Theodorakis
2009-Jan-22, 05:43 PM
... I think it was also not recognized because a new planet was just not imaginable.

http://en.wikipedia.org/wiki/Uranus

Could be; the wiki article indicates even Herschel thought it was a comet for awhile.

Nick

m1omg
2009-Jan-22, 05:58 PM
I think many saw it even during prehistoric and ancient times, the problem was that nobody in those time really gave much attention to very faint objects, and if one person saw it the rest of the village would say it is not there because you have to have good eyesight to see it.

antoniseb
2009-Jan-22, 06:06 PM
Antoniseb might be able to spot it. He has those Chuck Yeager eyes! :)

I *had* those eyes. I did look for Uranus on some dark dry nights, and was never confident I'd seen it until I saw it with my 11x80s, and then confirmed it visually again.

I can imagine some seriously sharp-eyed OCD student of Hipparchos trying to map all the sixth magnitude stars in the Zodiac (despairing over Scorpio and Sagittarius) but still somehow stumbling over Uranus as he checked his work.

If it happened, he didn't get published in the right journals. :)

ngc3314
2009-Jan-22, 06:14 PM
I *had* those eyes. I did look for Uranus on some dark dry nights, and was never confident I'd seen it until I saw it with my 11x80s, and then confirmed it visually again.

I can imagine some seriously sharp-eyed OCD student of Hipparchos trying to map all the sixth magnitude stars in the Zodiac (despairing over Scorpio and Sagittarius) but still somehow stumbling over Uranus as he checked his work.

If it happened, he didn't get published in the right journals. :)

Come to think of it - how deep did naked-eye star maps go? I can't recall seeing any really old ones going deeper than maybe 4th magnitude, but I'm no enough of a student of these things to have seen a big sample. Some depictions of the Pleiades suggest maybe 5 or 5.5 in that little region, but that's based on number and not particularly exact location.

Amusing anecdote at own expense: a couple of months I was doing emote observing woth a 0.9m telescope and had trouble recognizing the field of a calibration star. Huge bright saturated thing in the corner. Nothing nearby on the map. Hey, waitaminnit, Feige 110 is near the ecliptic, and if I turn up the contrast that blob has four dim companions in a SSE-NNW line... I had rediscovered Uranus with a 10-arcminute field. What would the odds be? Anyway, had Herschel and everybody missed it, I'd have nailed it by now.