IPB

Welcome Guest ( Log In | Register )

3 Pages V   1 2 3 >  
Reply to this topicStart new topic
So what colour is Uranus really?
karolp
post Oct 26 2006, 01:19 PM
Post #1


Member
***

Group: Members
Posts: 147
Joined: 14-April 06
From: Berlin
Member No.: 744



Photos from the Voyager era show it to be on the border of blue and green, particularly greenish in some of them. On the other hand, amateur astronomers report from their backyards a definite "blue blob". So what colour would Uranus appear to human eye? Was the greenish tint made up as a distinction from Neptune? Or was it some flaw in image processing?


--------------------
Go to the top of the page
 
+Quote Post
djellison
post Oct 26 2006, 01:28 PM
Post #2


Administrator
****

Group: Chairman
Posts: 13762
Joined: 8-February 04
Member No.: 1



I've seen it through a 16" scope, and it was a small bluey-green ball - looking at the amateur obs of it, this isn't too far from how I remember it

http://i105.photobucket.com/albums/m213/me...ectspelling.png

But there is a whole variety from bright bright blue to near a turq-green in the images I've seen.

Doug
Go to the top of the page
 
+Quote Post
karolp
post Oct 26 2006, 01:39 PM
Post #3


Member
***

Group: Members
Posts: 147
Joined: 14-April 06
From: Berlin
Member No.: 744



Check this out (the occultation was visible in Australia):

Uranus occultation

And yes, I have also seen a great variety, especially in printed books and magazines. But what is its true colour? With the DPS taking place recently there must have been some mention of that as well... Especially that the colour is probably changing a bit due to the rapid increase in atmospheric activity with Uranus near its solstice where both hemispheres get sunlight and things get stirred up a bit...


--------------------
Go to the top of the page
 
+Quote Post
MizarKey
post Oct 26 2006, 03:32 PM
Post #4


Member
***

Group: Members
Posts: 289
Joined: 2-March 04
From: Central California
Member No.: 45



karolp, thanks for sharing those occultation images, I've always been a big fan of the moon passing in front of the outer planets and brighter stars.


--------------------
Eric P / MizarKey
Go to the top of the page
 
+Quote Post
Rob Pinnegar
post Oct 26 2006, 03:44 PM
Post #5


Member
***

Group: Members
Posts: 501
Joined: 2-July 05
From: Calgary, Alberta
Member No.: 426



Those occultation pictures are neat but I'm sure they've been altered a little. Look at how bright Uranus appears to be, compared with the limb of the Moon! Although Uranus is probably several times more reflective than the Moon, it also gets 400 times less sunlight. I expect its brightness has been increased to make it more visible.

A lot of kids' astronomy books portray Uranus as green and Neptune as blue, but (as has been pointed out above) this is probably just "artistic license" to help children distinguish them from each other. Uranus is blue, but it's not as blue as Neptune -- it has that touch of green to it which Neptune pretty much completely lacks. More of a cyan-blue.
Go to the top of the page
 
+Quote Post
JRehling
post Oct 26 2006, 07:01 PM
Post #6


Senior Member
****

Group: Members
Posts: 1572
Joined: 20-April 05
Member No.: 321



QUOTE (Rob Pinnegar @ Oct 26 2006, 08:44 AM) *
A lot of kids' astronomy books portray Uranus as green and Neptune as blue, but (as has been pointed out above) this is probably just "artistic license" to help children distinguish them from each other. Uranus is blue, but it's not as blue as Neptune -- it has that touch of green to it which Neptune pretty much completely lacks. More of a cyan-blue.


I agree. I've seen Uranus and Neptune in very tight succession (within 5 minutes) of each other, and the difference (besides the very large difference in brightness) was obvious: Uranus is greener... but still blue-green, not out-and-out green.

I've also seen Uranus and Mars in rapid succession, which is an astonishing difference in color -- in some respects, the largest difference in color you can see in the sky without developing a long exposure of something or other.
Go to the top of the page
 
+Quote Post
Guest_Kevin Heider_*
post Oct 26 2006, 08:44 PM
Post #7





Guests






Uranus July 8, 2005 with a Meade 12 inch 200LX-GPS f/10.

-- Kevin Heider
Go to the top of the page
 
+Quote Post
4th rock from th...
post Oct 26 2006, 11:59 PM
Post #8


Member
***

Group: Members
Posts: 292
Joined: 21-April 05
From: Portugal
Member No.: 347



Well, to me visually it looks the same color as the light blue on these pages, for example on the second row background, were you have "Front Page" "Forum Guidelines", etc.
This on a 8'' telescope, so not much light to detect subtle colors, but certainly not much saturated light blue.

Neptune is close to the background on the page footer, where you have the time.

This to me of course, but we are talking about visual appearance.


--------------------
_______________________
www.astrosurf.com/nunes
Go to the top of the page
 
+Quote Post
algorimancer
post Oct 27 2006, 02:06 AM
Post #9


Member
***

Group: Members
Posts: 587
Joined: 20-April 05
From: League City, Texas
Member No.: 285



It's been 15-20 years since I last had a look at Uranus, but I recall it as a small but sharp and brilliant emerald green disc through the 6" reflector I had at the time. These days I have an 8" Celestron, but unable to get much use out of it due to the laser correction I had on my eyes a few years ago... wonderful vision in bright daylight, but bad flares and ghosting in the dark. Anyway I'm having plenty of fun with the math and software end of things these days.

Some of this perceived color variation may be due to the optical glass in the scopes and eyepieces. Part of it may be individual variation. I'm pretty sure that the true color is green, and blue for Neptune. Saturn of course has that nice golden hue, but I don't recall that Jupiter had any special color beyond levels of gray; the red spot never looked red to me.


QUOTE (Kevin Heider @ Oct 26 2006, 03:44 PM) *
...Uranus July 8, 2005...

That last one was really nice, Kevin. Someday I need to try that image stacking thing.
Go to the top of the page
 
+Quote Post
odave
post Oct 27 2006, 01:06 PM
Post #10


Member
***

Group: Members
Posts: 510
Joined: 17-March 05
From: Southeast Michigan
Member No.: 209



I've always seen it as greenish through my battery of 'scopes (80mm/8"/12.5"), especially when compared to Neptune in the same session, as JRehling notes. Now is a good time to try that, with both of them hanging out relatively close to each other in Aquarius & Capricornus in the early evening.

Jupiter's red spot has been very pale for the last several years, and they way I've detected it most often is by the gap it makes in the SEB. Find the gap first, then concentrate on it and the spot becomes a little more apparent. It certainly doesn't hit you over the head these days.

But as others have noted, we are using our own built-in biological photodetectors in the end, and they have their quirks. This discussion reminds me of the whole green star question, but we're dealing with emitted light there. Interesting stuff!


--------------------
--O'Dave
Go to the top of the page
 
+Quote Post
ugordan
post Oct 27 2006, 01:18 PM
Post #11


Senior Member
****

Group: Members
Posts: 3564
Joined: 1-October 05
From: Croatia
Member No.: 523



QUOTE (odave @ Oct 27 2006, 02:06 PM) *
This discussion reminds me of the whole green star question

QUOTE
By chance there are no stars nearby that would have produced green colors had their spectral shapee been just right.

Isn't the whole point that a blackbody cannot have an apparent green color (it cannot have a spectral shape "just right") because of the blackbody curve and the way color is perceived by humans? This statement above makes it look like there can be green stars in reality and that it just so happens none of them are near enough...


--------------------
Go to the top of the page
 
+Quote Post
odave
post Oct 27 2006, 01:32 PM
Post #12


Member
***

Group: Members
Posts: 510
Joined: 17-March 05
From: Southeast Michigan
Member No.: 209



Yup, I remember quite a debate on this topic back in my Usenet days. This article has a better explanation.


--------------------
--O'Dave
Go to the top of the page
 
+Quote Post
J.J.
post Nov 11 2006, 09:57 PM
Post #13


Junior Member
**

Group: Members
Posts: 84
Joined: 22-March 06
Member No.: 722



In almost all of the amateur images I've seen of both planets (such as those on the ALPO site), Uranus is definitely more greenish than Neptune, the latter of which is usually an out-and-out blue.


--------------------
Mayor: Er, Master Betty, what is the Evil Council's plan?

Master Betty: Nyah. Haha. It is EVIL, it is so EVIL. It is a bad, bad plan, which will hurt many... people... who are good. I think it's great that it's so bad.

-Kung Pow: Enter the Fist
Go to the top of the page
 
+Quote Post
Airbag
post Dec 5 2006, 06:44 PM
Post #14


Member
***

Group: Members
Posts: 402
Joined: 3-August 05
Member No.: 453



Attached Image


Slightly off topic...I was inspired by HST's near IR image of Uranus to create this shallow glazed ceramic bowl.

Airbag
Go to the top of the page
 
+Quote Post
Floyd
post Dec 5 2006, 07:13 PM
Post #15


Member
***

Group: Members
Posts: 626
Joined: 4-September 06
From: Boston
Member No.: 1102



That is really great. Have you created bowls for other planets? Mars?

Floyd


--------------------
Floyd
Go to the top of the page
 
+Quote Post

3 Pages V   1 2 3 >
Reply to this topicStart new topic

 



RSS Lo-Fi Version Time is now: 21st September 2014 - 12:08 PM
RULES AND GUIDELINES
Please read the Forum Rules and Guidelines before posting.

IMAGE COPYRIGHT
Images posted on UnmannedSpaceflight.com may be copyrighted. Do not reproduce without permission. Read here for further information on space images and copyright.

OPINIONS AND MODERATION
Opinions expressed on UnmannedSpaceflight.com are those of the individual posters and do not necessarily reflect the opinions of UnmannedSpaceflight.com or The Planetary Society. The all-volunteer UnmannedSpaceflight.com moderation team is wholly independent of The Planetary Society. The Planetary Society has no influence over decisions made by the UnmannedSpaceflight.com moderators.
SUPPORT THE FORUM
Unmannedspaceflight.com is a project of the Planetary Society and is funded by donations from visitors and members. Help keep this forum up and running by contributing here.