Uranus through a 10" Dob, what to expect

[sophiecentaur]

On 9/9/2016 at 20:58, rockystar said:

I recently read an article suggesting that you can't see a colour unless you have a name for it. May sound silly, but it went on to describe a tribe that doesn't have a name for the colour blue, so when shown 7 green spots and 1 blue one, they struggled to identify the blue spot (which I \We could easily identify); conversely, this tribe has different words for different shades of green, so when shown a bunch of green spots with one a very different shade of green, they easily found it (whereas I struggled).

The word blue didn't exist when Homer wrote the Odyssey, and this is a suggestion as to how he experienced the colour of the sea.

Not sure how exactly this relates, but I maybe your own experience of colours has something to do with how you see it.

Good comments there. Colour is to light as Music is to sound. Colour is a cultural thing and the use of colour as a description means that it is appreciated in different ways in different societies, according to their needs. Newton reckoned that colour could be broken down into just Six categories. The seventh was just introduced, apparently, because seven was a much more 'significant' number and Newton (and most people of his time) were into magic and religion. Compare that number with the range of colours available on a paint mixing shade card. The 'violet' in CIE colour space is not even the same as spectral violet.

The Wiki article could only quote evidence of the mechanisms that our ancestors had available and not how they actually used them. Anthropology is an inexact Science.

[rockystar]

On 10/8/2016 at 20:17, bomberbaz said:

Do you still have a link to the article Lee. Think it might be usefull to many of us to rwad and see if this apparent strange phenomenum affects us all!

I can't find the article, but here is a clip from the Horizon episode,  that the article took it's detail from: http://www.boreme.com/posting.php?id=30670#.V_uE2vkrKM8

 

[John]

I've been viewing Uranus with my 100mm refractor tonight.

The planet was quite easy to find and showed as a reasonably bright star in my 6x30mm finder. At 38x magnification the planet did not look quite like a star but the disk was not clearly defined either. It did appear pale blue with pale being the operative word.

At 90x the planetary disk was clear, though small and Uranus looked quite different from nearby stars.

At 180x the disk was very obvious and there seemed to be some darkening around the limbs giving the effect of a very small pale blue ball or bead rather than just a flat dot. This effect was more pronounced up to 257x but above that the seeing conditions and limited scope aperture started to take their toll and the overall view was less satisfying despite the planets larger size in the field of view.

The best view tonight was at 225x I think. No signs of the moons though - mag 13-14 objects are just too faint for this scope in my back yard to pick up !

 

[bomberbaz]

Some good reading in this thread.  Hoping to try a bit of planetary moon spotting at sgl12 ?

[rockystar]

4 hours ago, bomberbaz said:

Some good reading in this thread.  Hoping to try a bit of planetary moon spotting at sgl12 ?

Me too - i believe Uranus is at opposition in the next couple of days, so a good time to view it.

[niallk]

I had a great view of Uranus last week - caught 4 moons, and got Triton with Neptune too! Really quite magical to see them with your own eyes across those vast distances.  Afterwards I had to go look up stuff from the Voyager fly by - I have dim memories of it on the news etc when I was a kid: what an amazing programme 

 

[John]

1 hour ago, niallk said:

.... caught 4 moons, and got Triton with Neptune too! Really quite magical to see them with your own eyes across those vast distances..... 

 

 

Great stuff

I've not got further than 2 Uranian moons plus Triton so far but Uranus will be around for a while longer.

100% agree with the feeling of awe when viewing these tiny faint specks of light. Triton is the most distant rocky body that I'm able to see from my back yard. Smaller than our moon and yet 27 billion miles away !

 

 

[Dave In Vermont]

On Monday, October 10, 2016 at 04:37, John said:

I can see Neptune and Uranus as defined disks with my 4" refractors but quite a bit of magnification is required, especially on Neptune where the planetary disk is just 2.3 arc seconds in diameter, which is around the separation of the star pairs in Epison Lyrae, the famous "Double Double". Their colour tints are apparent but rather washed out in smaller apertures. With my 5.1" refractor the colour tint is more obvious and I've managed to see Neptune's brightest and largest moon Triton using averted vision. With my 12" scope the colours are clearer again and Triton can usually be spotted with direct vision although it's still a very faint point source. I have also managed to spot the moons Titania and Oberon around Uranus with the 12" scope but these are slightly fainter than Triton so a real challenge even with the 12" aperture I find.

The most striking colouration of Uranus that I've witnessed came when it was very close to the Moon a year or so back and I could get both the bright lunar lumb and Uranus in the field of view at 199x with an ultra wide eyepiece in my 12" scope. On that occasion the Uranian disk was remarkably colour saturated I thought and really very beautiful as it appeared to hang in space just above the lunar limb and rather like the famous Apollo 8 "Earthrise" photo albeit with a much tinier planetary disk and one that was considerably further away than the Moon of course !

I've often wondered since whether the strong colour was a product of having the bright lunar segement in the same field and since then I've taken a different view on the need for dark adaptation when planetary observing (or not !)

An excellent post, John. Thank you! However you left out one tiny detail: What colour did you see Uranus and Neptune as being? You said the coloration was quite pronounced, but neglected to state WHAT the colour was! LOL!

Love it!  

Peace -

Dave

PS - An article in the latest (November) issue of Sky & Telescope magazine on the colours seen of Uranus and Neptune. I feel rather plagerized!

[Stu]

On 10/10/2016 at 09:37, John said:

I've often wondered since whether the strong colour was a product of having the bright lunar segement in the same field and since then I've taken a different view on the need for dark adaptation when planetary observing (or not !)

I definitely agree with this John, I've found the same when observing Jupiter; The colours appear stronger when the moon is bright and it is in the same area of sky. I'm sure it's because your colour sensitive cones are more likely to be being stimulated by the higher brightness levels.

I have a vague memory that I had a similar experience on M42 in my 4". Normally I just see it as shades of grey, but I think one night when the moon was bright, but not too close I saw it as a similar green colour as I've seen it in large scopes e.g. 12" or more.

[Analysis Paralysis]

On 10/10/2016 at 09:04, chiltonstar said:

My 180 Mak shows Uranus as a defined, blue-white disk, and Neptune as a little bluer and smaller, but clearly a disk. Interestingly, my 127 Mak shows slightly more intense colours on Uranus, but not on Neptune - must be a feature of old eyes!

Chris

Hi Chris

Did you ever glimpse Triton?

Mark

[chiltonstar]

11 minutes ago, Analysis Paralysis said:

Hi Chris

Did you ever glimpse Triton?

Mark

I've spotted it a couple of times this year with the 180 Mak.

Chris

[Analysis Paralysis]

1 hour ago, chiltonstar said:

I've spotted it a couple of times this year with the 180 Mak.

Chris

Thanks. I'm trying to choose between 180 mak and 9.25 in SCT. Any thoughts?

[John]

24 minutes ago, Analysis Paralysis said:

Thanks. I'm trying to choose between 180 mak and 9.25 in SCT. Any thoughts?

I've seen Triton twice now with my 130mm apochromat refractor. It's a touch easier than the Uranian moons but still quite challenging.

[MarsG76]

+1 for discs, Uranus is easily identified as a Green disc and Neptune, eventhough smaller, is definitely not a star, very blue in my experience.

[BGazing]

On 11/10/2016 at 22:27, Stu said:

I definitely agree with this John, I've found the same when observing Jupiter; The colours appear stronger when the moon is bright and it is in the same area of sky. I'm sure it's because your colour sensitive cones are more likely to be being stimulated by the higher brightness levels.

I have a vague memory that I had a similar experience on M42 in my 4". Normally I just see it as shades of grey, but I think one night when the moon was bright, but not too close I saw it as a similar green colour as I've seen it in large scopes e.g. 12" or more.

Wouldn't M42 be bright enough to  fire up the cones all by itself? I mean, it's bright enough to spoil night vision...

[Stu]

7 hours ago, BGazing said:

Wouldn't M42 be bright enough to  fire up the cones all by itself? I mean, it's bright enough to spoil night vision...

It may well be. Strangely, since posting that I find a regularly see a greenish tint to M42 even in my 4". I guess that is just a matter of looking for it and learning what it looks like. I used to think I didn't see colour on Jupiter but definitely do now.

[Stub Mandrel]

10 hours ago, Stu said:

I used to think I didn't see colour on Jupiter but definitely do now.

Jupiter is definitely colourful (not just coloured) in my 150PL

[Stu]

10 minutes ago, Stub Mandrel said:

Jupiter is definitely colourful (not just coloured) in my 150PL

Definitely gets more colourful with more aperture. Haven't had a 6" scope for a while, but colours in the 8" SCT were very obvious.

[Analysis Paralysis]

On 11/10/2016 at 21:54, John said:

Great stuff

I've not got further than 2 Uranian moons plus Triton so far but Uranus will be around for a while longer.

100% agree with the feeling of awe when viewing these tiny faint specks of light. Triton is the most distant rocky body that I'm able to see from my back yard. Smaller than our moon and yet 27 billion miles away !

 

 

Hi, I would check that distance ?. Pluto is less than 4 billion miles away.

[John]

50 minutes ago, Analysis Paralysis said:

Hi, I would check that distance ?. Pluto is less than 4 billion miles away.

Good spot from my post a year and 3 months ago !

I missed out the decimal point between the 2 and the 7 so it was a typo

Triton is still the furthest rocky body that I've seen

 

[Analysis Paralysis]

2 hours ago, John said:

Good spot from my post a year and 3 months ago !

I missed out the decimal point between the 2 and the 7 so it was a typo

Triton is still the furthest rocky body that I've seen

 

Hi John,

You're welcome. I've only recently joined SGL. Surprised no one else noticed, but I am a bit of a pedant!

As, you say, it is very impressive. I was thinking the same about how amazing it will be if new horizon probe hits its next target next year about 4 billion miles from earth, when the target kuiper belt object is only about 20 miles in diameter, and sends photos back! What would Galileo and Newton have thought?!