The origin of the problem with observed star colours is an interesting one. Much has been written about star colour, and very likely much will be written about it into the future. During the 1800s, conventional observations and accepted theories about the true nature of star colours were adopted with great interest and held with some real furore. Without having the important advantage of the use of astronomical spectroscopy, little was then known about surface temperatures or luminosity of stars and its own critical relationships to observed colour. Using some careful and astute observations, some everyday information was obtained. Yet much of this today can be discarded as either irrelevant or unimportant knowledge without much use. Sadly today, there still continues to be many poor and inaccurate views about star colours and its origin — some of which has now persisted for one-hundred years or more. Another of the very worst aspects has been the adoption of grandiose colours having literally thousands of many different colour names, technically known as colour descriptors. It remains a little hard to comprehend how commonly expressed border-line and subjective colours can exist; like gold, crimson, lilac, indigo, grey or ashy can be readily or usefully describe star colours for most practical visual observers.
Some do often innocently exaggerate the colours that they see probably only wanting to present more exotic colours to make them seem either more original or accepted within the amateur astronomical community. Few may be viewed as faux pas, but many do still continue to appear in articles throughout the popular astronomical press.
In my own opinion several of them can only be described as “new-age charlatans”. Several claiming either some personal superior colour vision or knowledge based on the quite whimsical notion of the observer being the better sex or in having better colour perception. I have even seen star colours seriously presented as apricot, peach, amber, silver-white, lemon-brown, beige, khaki, or even turquoise! These were even mixed with so-called reflectance terms like gloss, translucency or shadowy — the latter meaning uncertain, insubstantial or unreal colours. (No observed colour is more straight forward.) Such meaningless descriptions are just pure and utter nonsense because they are visual colours, which verbally have quite arbitrary meanings — meanings that convey nothing at all to another person and are only useful to the individual that gave them. Worst with these kind of observers is that the colours they are describing are physiologically impossible to see at night.
The logical reasoning to this view is these are all highly rich saturated colours (something we will argue against and discuss in depth within this very Webpage) Fuerthermore. these are odd mixtures with the tones of black, greys or white — something that is not seen in the continuous spectra of stars. I do think these types of amateur observers must be immediately discredited, if only because they give a very poor representation of the many good, sensible and dedicated amateur astronomers throughout the world.
Perhaps, as some other earlier readers of this text have said, I am being a bit too critical of the situation. I only wish here to highlight that using more specific or simpler colours are far more sensible than in trying to match precisely what subtle shade of colouration one particular star or double star system appears to be.
With star colours, much of the biological and chemical mechanism regarding colour vision unfortunately does not work very well at low illuminations. This is a major limitation for visual observers to overcome. These serious flaws really lie with the specialised cells known as cones located along the retina of the eye, being the main sensor that gains nearly all of the light needed for interpreting colour. It seems the human eye for all its true biological wonder was just never designed for good night vision. This is bad news for the amateur astronomer who is trying to percieve fainter objects and to see colour or spectral-based phenomena. Worst, there is no doubt that the age of the observer is likely another contributing cause for the eventual loss of the ability to interpret the spectral range. More unfortunate is that the younger the individual, the less able they can describe the visual colours they see just through lack of experience! Yet the real experts in recent times about eye colour perception have been made by several French visual observers, with several interesting papers in the last twenty to thirty years or so. For example, I have presented in Southern Astronomical Delights the translated version by Paul Biaze’s “Les Couleurs des Étoiles” or [The Colours of Double Stars] written in the late-1950s which is quite analytical and very innovative. A further excellent summary of this subject about star colour appears in David Malin’s Colours of the Galaxies (1996), which is recommended reading for all amateur observers.
Overall, the study of colour perception for stars is still incomplete. This general article is about the cause of colours that we see in telescopes and why they are so hard to observe. It was also written to counteract the seeming avalanche of several new double star observers who have been claiming that they have some superior vision or better colour perception.
Please, if you are one of those observers that believe what I am saying here is completely wrong, then I do suggest you reading the next four paragraphs very carefully before reading the rest of the text and condemning me for life.
At the telescope any observed colour is more often than not fairly poor. This indisputably is a physiological problem, as the human eye at night cause the loss of colour vision. The important mechanism of our vision lies with the so-called rods and cones attached over the human retina. Each eye contains an average 137 million light-sensitive cells with the mean density of 650 per square millimetre. These are approximately ratioed as 617 black and white rods with only 33 being the colour cones. About 7 million of the total are cone cells, whose average density are divided into thirds — equally being divided as either red, blue or green-sensitive.
Rods are designed to measure the intensity of light in the eye (greyness) and respond very little to colour. As light intensities vary so much, ranging from full sunlight to the near pitch-blackness of night, the need for such a mechanism is obvious. It also affords the detection of contrast. An analogy of this is similar to the controls of black and white televisions. The “rods” will work regardless of the intensity of light.
Cones are the colour receptors, and as their names suggest, are in the shape of a cone whose diameters reduce almost to points. For this reason they are poor light receptors, but with enough illumination, the wavelengths coming into to eye can be separated in to their component colours. The signals are then sent along the optic nerve of the brain and interpreted as colour. The details on how our eyes do this is probably unnecessary to describe for the general reader. Needless to say, the understanding of the cause is chemically very complex, relying on many reactions and processes.
For all visual observers much of the star and deep-sky colours are lost to our eyes during the night. The simple reason is that cones have known thresholds for colour sensitivity, and below particular light energies (flux) they almost all completely cease to function. Consequently, when we look at our general surrounds during the night, we see only a slight range of “greyness”. Looking through any telescope, we are immediately exposed to the wide field illumination of the field stars and the astronomical object(s) in question. Most stars just appear white in colour, but in some circumstances, like the very blue or very red stars, we do begin to see some distinct colour. Also the fainter the star or object the less colour we see are able to see. Hence, colour is also magnitude dependant. (Further discussed in Star Colours : 2)
Star colours that we see are quite different from what we mostly see during our everyday living because at night we perceive very few hues. This is due to the colour component known as saturation that can be described as the degree of whiteness in any perceived colour. Importantly, saturation is fairly weak in all stars. For many astronomical objects these will produce only pale or washed-out colours and never intense ones. The only true exception is probably the deep-red carbon stars which also visually appear to have a little blue or yellow light contributing to their general spectra and appearance. Such stars, however, are very unusual and rare.
Experience finds that the more intense colours at night simply cannot be observed. The degree of saturation also only slightly varies between different individuals, and gets generally worst with age. Importantly it is also visually dependant on the background colour it is seen against.
The colour able here shows the colours red, orange, yellow, light blue and deep blue. Colour saturations above 10% are never seen in stars or nebulae. 0% colour saturation is the pure white. All 100% saturation colours are often termed as pure colours.
The following figure shows the effect on 20% saturated colours seen against either black or white backgrounds. Each colour against each its alterative background are identical, but visually our eyes see that those against the lighter background make the inside circle colour seem to be slightly darker. This is caused by the colour contrast as seen by the eye and is comparable to looking at the stars. For example, seeing stars during the hours of darkness when compared to seeing stars against the background of either twilight or daylight times. Similarly, pairs with quite different surface temperatures finds similar visual effects, which enhances the visual colour differences. Amateur observers should also note that as the magnification is increased by using different eyepieces that background field is seen as slightly darker and this has an effect of changing the observed colour slightly.
Any real need for estimating the observed colour in telescopes is likely not very important for most visual observers, but it is for those engaged in writing astronomical descriptions or promoting astronomy. Such colour reports are both interesting and important to advise, whose knowledge may guide other deep-sky observers and amateurs to sme of the more attractive targets.
Based on the experiments by visual physiologist Denis Baylor in 1978, it is possible to conclusively dismissed the ecumenical misconceived notions of colour discrimination through the telescope. (See References) These original detailed experiments were conducted at the Department of Neurobiology at Stanford University whose aim was specifically to measured the eye’s photon response in darkness. Attaching a photoelectric photometer to individual rod and cone cells in the human retinas, he then measured photoelectrically the response of the photons of various monochromatic colours. After analysing the results, his main conclusion found that at low illumination, all the cone cells switch off, and nearly ceasing their entire electrical function. It is for this reason that the loss of colour vision at night was explained and the first time quantatively determined. Baylor further says about his results;
‘This state of affairs makes it impossible for one cell, either a rod or cone, to signal separately wavelength and intensity. Consider a single rod upon which falls 100 photons of 550nm wavelength. These photons will be absorbed with the probability of say 10%, so that a total of ten absorptions will occur. Ten absorptions would also occur if 1000 photons were incident at 600nm. A particular wavelength therefore has the mean probability of absorption of only 10%. Since the cell reports only the number of photons absorbed, the signals generated by the two coloured lights are identical, even though their wavelengths are different. Hence no colour (wavelength) information is available. This explains why in starlight, where only the rods contribute to vision, we have no colour sensation.’
From this we can conclude as the rods receive the light, then our brains then try to interpret the colours it is seeing. Furthermore, as the star colours are never saturated, so what we generally see is only slight variations in hues.
One of the first important colour scheme in stars was first made in 1901 by the variable star astronomer and editor of the Astronomical Journal Seth C. Chandler (1846-1913) (Chandler Scale - CI) producing seven basic colours. The southern double star observer R.T.A. Innes (1861-1933) was one of Chandler’s greatest critics stating that he placed little credence in knowing star colours as they could be equally obtained photographically using two films or by instrumentally by photometry. I could not find any information relating to whether Hagen accessed Chandler’s work, but personally I see much usefulness in Chandler’s Scheme for visual observers because I can easily distinguish these colours in the telescope and I assume the same for the majority of people !
It was Rev. John G. Hagen (1847-1930), who incidentally specialised in eclipsing binaries and produced the famous Atlas Stellarum Variabilium between 1899 and 1908, that was to produce a new logical colour scale during 1924. This scale essentially was the later version of the previous and poorly adopted Chandler Index. Now known as the Hagen Colour Index (HCI), the labelled star colours ranging between the values of -3 for Blue and +10 for Red with 0.0 corresponding to the B-V value of 0.0. This particular colour scheme has remained the nomenclature now often adopted by amateurs who do variable star observations or for the measurements of pairs.
Colours in this scheme were Blue, Bluish, White, Yellowish, Yellow, Orange and Red. Hagen simply just adds additional colour values for these seven basic colour elements.
| -3 | Pure Blue |
| -2 | Pale Blue (Bluish) |
| -1 | Blue / White |
| 0 | Pure White |
| 1 | Yellowish/white |
| 2 | Pale Yellow (Yellowish) |
| 3 | Pure Yellow |
| 4 | Orange /Yellow |
| 5 | Yellow / Orange |
| 6 | Pure Orange |
| 7 | Reddish / Orange |
| 8 | Orangey / Red |
| 9 | Red / Orange |
| 10 | Pure Red |
Most visual observers tended to use the Hagen Colour Index (HCI) which relates closely to stellar surface temperatures and the B-V Colour Index. No one truly adapted this as an “analytical” method, but as an extra means of determining the “correct” position angle of both the stars, especially when the magnitudes are nearly equal.
Note: The original observer’s designation overrides the estimation of the brightest against the faintest star. This means the designation of A and B components are preset by the discoverer. The HCI has some analytical basis, however, the linearity with visual divisions in quite poor. Ie. The values of say white to yellowish are different from say from blue to bluish or red to reddish.
Figure 3 shows the Hagen Colour Index Scale with both 10% Saturation, the likely maximum visible colour, and 20% Saturation. I have contrasted the colours against both black or white backgrounds so the visibility of the colours and the contrast effects can be seen. The Figure above clearly shows these differences. All observed colours will be also slightly different when they are pinpoints, and the colour presented here are closer to the defocussed star images that can be seen in the telescope. Observers should note that I have calculated the colours to be approximately 10% and then I have had to make several small adjustments so that the colours look a bit more consistent. However this changes are quite likely inconsequential for many visual observers. Most stars will be fainter than the colours presented here and nearly all of the fainter stars will have almost insignificant saturations.
It was M. Minnaert who first discussed star colours in more modern terms. If we assume that star colours are based on the black body properties of objects, as seen in some ultra-hot furnace (Ie. The famous simple experiment is to heat small pieces of metal (like Tungsten) where, as the temperature rises, the metal becomes distinctly coloured. As the temperature of the metal rises, the colours change from red-hot, yellow-hot, white-hot then blue-hot. This follows the observed spectral sequence and B-V colour index — but without green.
Minnaert then adopted the series of eight separate colour groups he could distinguish by eye. He then did a simply blind experiment by comparing his colour estimates against the B-V colour index, which proved to have an observed high correlation. From this, he then first achieved the feat of distinguish the spectral class letter of the object. Minnaert gained much kudos for this achievement in his day !
Minnaert also investigated the colour of the white and yellow stars, finding that they could distinguish the yellow ones into white-yellow, light yellow, pure yellow and deep yellow. (The reason for this, I think, is that the eye is more sensitive to seeing this part of the spectrum, especially when compared with the red, and the far blue.) Interestingly, his experiments validates the problems of colour saturation. His book concludes that only eight major or primary star colours each corresponding to the mid-spectral classes of O, B, A, F, G, K, M, S.
Figure 4 shows the colours of the Spectral Classification at 10% Saturation. The colours can be estimated in the telescope with care, but observers should note that these are the maximum colours and most of the stars have much lower saturated colours. I have contrasted the colours against both black or white backgrounds so the visibility of the colours. The colours here are suitable for using in drawings of star charts where the spectral class is required.
Again, anyone using the colours for observational comparison should ONLY use this 10% SATURATION SCALE.
According to David Malin (AAO), it was the astronomer Leslie Morrison from the Royal Greenwich Observatory who attempted visual observation of stars through the transit telescope, and doing a blind test, could guess the Spectral Class of the star in question! Each class could be seen and ascertained with the eye, with each have only three or four shades of certain colours, with the solitary “non-colour” of white. The fourteen “valid” colours in this second system were (in order);
| BLUES | WHITES | YELLOWS | ORANGES | REDS |
|
Deep blue Light blue Blue-white |
White |
White-yellow Light yellow Pure yellow Deep yellow |
Yellow-orange Light orange Deep orange Red-orange |
Orange-red Light red Deep red |
For double star observers such methodologies have been already established using scales like the Hagen Colour Index (HCI). This scale has values between -3 and +10, describing the possible range of fourteen double star colours — from blue to white to yellow to orange to red. This roughly mimics the range seen in astronomical spectra, in stellar surface temperatures and spectral classes. However, the problems for double stars observers is that use this particular index, finds the fundamental inherent weakness is a scale is that it does not differentiate between the different colour saturations. Furthermore it takes no account of the stellar magnitude. Although this scale is quite arbitrary between observers, different eyes will certainly see different colours. Unfortunately, the HCI system leaves too large a range of observable possibilities for the many different colours. Moreover, detecting colour is also very observationally troublesome to see as the stars more often than not appear simply as point sources. Often by just simply defocussing the star into small plate-like disks can be applied to partially exacerbate this problem.
Figure 5. ⇒ (On the Right-hand
Side)
gives the approximate look of the vast majority
of star colours in the telescope. This is based on 10%
Colour Saturation given earlier in the text.
A. The White Box on the lefthand side of the Figure shows the Hagen Colour Index Number, the approximate observed apparent colour and the Spectral Class it pertains too.
B. The White Box on the righthand side (at the top) is the reported colours sometimes seen by observers. I have labelled this as due to Contrast Effects because more often than not they are only seen in visual double stars.
C. The White Box on the righthand side (at the bottom) gives the pure monochromatic colours as they would be seen in a telescope. These of course do not exist in Nature and are given as comparison.
When reading some older books, texts and catalogues, you will sometimes find the use of the following abbreviations. I.e.
These main colour can also have the following additions: Colour that are less bright than normal are prefixed p pale — or if brighter in colour are r rich or d deep. I.e. pale blue, rich yellow, or deep red, etc. Colour tendencies towards any colour are sh but is very rarely used.
| Abb. | Colour |
| W | White |
| B | Blue |
| Y | Yellow |
| O | Orange |
| R | Red |
| P | Purple |
| G | Green |
| C | Grey |
| L | Lilac |
| A | Gold |
| S | Ashy |
Unconvincing colours, for example, a suspect yellow star would be Ysh (Yellowish) or Bsh (Bluish).
A further usefulness for this colour scheme is that the observer can quickly write down these abbreviations in his or her observation notes. Although the use of colour is likely not important, but it is an additional descriptor when checking the pair at some later date to differentiate equally bright components or in reducing observations.
Later use of the abbreviations now tend to favour the Hagen Colour Index (HCI), which relates closely to stellar surface temperatures. Using this index, visual observers should report as e.g. “-2 / 3”, being its pale blue primary and pure yellow secondary. Other additional colours were added later Ie. -0.5 for grey and -0.25 for green.
If the colour is a definite colour, report it as
eg."White" or "Blue" etc.
If the colour seems a definite tint, report it as eg.
"Yellowish" or "Bluish" etc.
If it seems either like a combination or range of
colours report it as "Bluish" or
"Bluish-White" etc.
If the colour can not be described, record it as
"Unusual" or "Colourless"
If the primary’s colour is seen but not the
secondary, record it as "Blue / - " etc.
I have read much about what is written about colour, and have found some interesting ideas that are worthy for elaboration and clarification. Below is an adaptation of some of my own notes and essays on colour, which I have slightly updated for relevance to astronomy and double stars.
One of the most interesting aspects is on the perception colour and the alleged differences between the sexes. Much of this has been generated by the fable that women have some kind of superior vision and colour perception. The modern scientific view has shown there are no significant differences between males and females in interpreting colour. Most of the current literature also still confirms this view. Recently, colour scientists have shown that the main differences in colour perception between males and females to be more psychological rather than physiological ones. The reasoning follows that for women their mothers and peers from an early age train their daughters and young girls in colour perception and colour matching, especially after puberty. Subjects are deemed to have improved “perception”, being merely based on their vastly larger and better colour vocabulary and knowledge.
Important examples are in colours seen nylon stockings, lipsticks and fabric colours displayed under fashion parade lighting. Naturally women, who typically are faced with applying face make-up, soon learn the subtleties of colour. Often this involves matching of cosmetics to achieve the desirable effects they want. This is also shown in the comparison or matching of many additional fashion accessories, such as shoes and handbags with their own clothing.
Men in life are generally not faced with any degree of colour matching, and psychologically often do not need or use such colour terminology. Others in this field of study say the biological need for women having the colour knowledge is to improve their attractiveness to their male counterparts. Some have said that certain colours, like red, are more noticeable by males. Ie. Males more often see red on females rather than on other males. Psychologists technically called this a distractor - basically a lure by females for a suitable mate and probably the reason why red is perceived as a warm and vibrant colour. The promotion of blood-red lipstick or rouge by the cosmetic companies, for example, heightens the fullness of the lips and cheeks. This suggests they are fertile and are seeking suitably healthy sexually partners. Red in our society also symbolises aggression and violence. This colour can appears as a natural flush on the face, especially on the cheeks and lips. When someone is angry or has undergone extensive physical activity. This physical response is the warning to others, suggesting they are in a more aggressive mood and are ready to fight or defend themselves. Red colours also often indicates having higher blood pressure, and the likelihood of increase in the hormone, adrenalin. Additionally, in male cases, the prominent male hormone, testosterone. Our response to the colour red is exploited, such as red flashing warning alarms or red traffic lights to stop vehicles thoroughfare. Even most police cars have red and blue flashing lights — the blue enhancing the intensity of the already prominent red warning.
There are many examples of using colour to reflect mood, and this is more likely derives from environmental differences. As yet, no physiological difference has ever been found to influence either the rods and cones of the retina to account for this. Colour may affect the individual’s emotional state, however, the observed effects are mainly influencing brain chemistry and the interaction of with various organic compounds including for the hormone and adrenalin release into the blood stream. Some recent studies on the nature of these mechanisms towards our understanding on this subject remains quite incomplete.
For our discussion here, the basis of the physiological chemical mechanism for all human eyes - male and female - is having the main chemical pigment known as 11-cis Retinal. This is available in the principle photoreceptors and is a photosensitive chemical component - working not too unlike the silver halide crystals used in black and white photography, that measure the light intensity. The 11-cis Retinal in the reaction combines with specific proteins, called amino acid glutamates, which then become the colour chemical interpreters for the photoreceptors. The human brain has acquired by evolution these latter proteins for colour discrimination and is some cases the erroneous recombination of the wrong interpretation of colour producing various colour defects.
The main problem with colour perception between the sexes is with the genetic defect known as colour blindness. It has been found that the so-called anomalous trichromacy affects some 6% of colour vision in men, meaning they are unable to properly discriminate the colours displaying reds and greens. Another 2% are so-called dichromats, and are deficient in the pigments needed for discrimination of both long and middle wavelengths. Men are also ten times more likely to have some form of colour blindness defects than women. Most colour blindness is caused by the known defect in one specific gene that causes lack of eye sensitivity by either the red or green cones, properly termed as protanopia. Another is the much less frequently diagnosed blue cone defect known as deuteranopia.
Overall, visual colour problems are often caused by the incorrect usage of the chemical pigments. In simpler terms, it works like CRT televisions, where one colour gun is working incorrectly and not targeting properly, or even has one gun is not functioning at all. I.e. Take out the red component so the colours that are seen are mainly yellows, blues and greens, etc.
Total Colour Blindness occurs in 1:40,000 individuals, equally between men and women, where the cones do not form from birth. Such persons are sensitive to high intensity light and have vision that is akin to your surrounds as they appear during normal vision in twilight, and of course, naturally with perceiving any colour. Sometime other individuals have no rods all, and have to rely solely on their cone vision. These individuals are completely “night-blind”, being medically diagnosed as hemeralopes.
Another more general fault is that the spectral range of the visual wavelengths narrows with age. Physiological causes for this problem is more likely because the rods and cones are slowly reducing in total numbers. This might be further combined with increasing inefficiencies of the chemical signals being sent to the brain along the neural pathways.
Although the visible impact is usually only minute. During the daylight hours there is always overwhelmingly a sufficient amount of light. Hence the general effects become far more pronounced only because less photons are available to detect colours or intensity of starlight. Ie. If the colour degradation were, say, 25% for example, and that some million photons were received in one second of time during daylight hours, then the loss of light would be of little consequence as there is already enough light available for colour discrimination. Yet if one hundred photons were received over the same period the overall effect would be more dramatic and obvious. To our eyes, this manifests as the gradual loss colour perception, so that the sky would becomes more “greyish”. (Note that if this postulate is true, this would mean have slightly more trouble discerning bright nebulosities in the telescope as we grow older.)
A secondary effect is that the range of observed colours also diminishes. Here the ability to see blues and reds, for example, at either end of the visible spectrum becomes harder and harder to see. As our eyes are not as sensitive to reds, then you should also find that the perceived blues intensity gradually gets slightly lesser over time. This combined with the decreasing light intensity will find that colours become less obvious to the individual. I suspect that the age where these effects start happens at the average age of about fifty-years old, though the actual age might varies between populations over several decades. (See Figure 6.)
Figure 6 shows the expected explanation for most of the loss of colour vision as we age. Although arguably subjective, it does explain what is happening regarding the general discussions about colour perception with people of various ages. Importantly, some people may never experience any loss of colour at all, while others may find these changes and differences sudden and quite dramatic. Again there is no real “better” or “worst” in this situation and certainly no superior colour vision. Those who claim otherwise are being misleading or are probably trying to justify their point of view.
Still unexplained in nature is why colour-vision in humans
are similar between the sexes, but is much more different
than the many other colour-visioned mammals. I.e. Apes and
monkeys have known significant differences in colour
perception between males and females. Typically, these
primates have males with two types of colour cones
dichromats while the females do have three different
colour cones or trichromats. The postulated reason
for this has been something to do with either behaviour
modification or being necessary for mate selection. [Some
religious discussions have used these particular facts
against Charles Darwin’s “Theory of
Evolution.”]
Note: Only 2% of all human males are dichromats — being probably the genetic eye defects from misaligned X-chromosomes (in the sex determining XY pair) that are responsible for vision.
The chemical proteins for the coloured-cone photo-receptors
are attached to the XX and XY. Interestingly women do have
the duplication of these cone receptors while males do not.
This easily explains the increased number of males that
have imperfect genetically colour vision. However this does
NOT mean that females have, as some submissions I
have read have claimed, of better or “improved
vision”, as the chemical and physical mechanisms are
just exactly the same. In evolutionary terms, our eyesight
maybe one of the earliest to develop especially as
keenness of sight has definite advantages for hunting of
animals or spear fishing fish for our sustenance.
Colour genetic defects in women may mean they can be
so-called tetrachromatic, which are likely women who
have had sons who are “dichromats”. (Jordan, G,
Mollon, J.D. “A study of women heterozygous for
colour deficiencies.”, Vision Research,
33, 1495-1508 (1993)) Here, they mismatch the
colours, and they have slightly better capabilities in
separating red to orange colours. However, such women are
literally one-in-a-million.
1. Malin, David; “The Colours of the
Galaxies”, Pub. Cambridge University (1996)
2. “Colour, Art and Science.” Ed.
Trevor Lamb and Janine Bourriau, Cambridge University
Press. (1995)
a. Baylor, Denis; “Colour
Mechanisms of the Eye”;
b. Millon, John; “Seeing
Colour”
c. Lyons, John; “Colour in
Language”
3. Gerstner, K.;“The Forms of Colour-The Interaction of Visual Elements.”; MIT Press (1986)
I would like to sincerely thank Tom Teague,
Luis Arguelles, Eddy O’Conner and Raffaello Braga for
their poignant views and for being the true inspiration for
this text on this page. However, Richard Harshaw deserves
special credit for some really interesting ideas and
innovative solutions regarding the colours seen in doubles.
One or two ideas by Richard have show pure genius and have
forced me to again question for some time on how to apply
these to stellar observations.
Note: All of the above are members of the unique 33-doubles
Yahoo! Group.
1. The definitions of the primary parameters of colour are hue, saturation and brightness. This is where hue is the dominant - just as Wien’s law dictates for the observed colours of stars. In brief the definitions are;
Hue is the discernable colour based on the dependant dominate wavelength, independant saturation or brightness.
Saturation is the observed degree of whiteness added to the colour.
Brightness is the observed intensity of the visible light from a source.
2. The subject of colour and its nature is known in science
of physics as Radiometry, and is specifically about
the measurement of electromagnetic radiation and light
— including the visible portion of the spectrum. Such
measurements, especially in astronomy, are made using
photometry, which measures and expressses light in
terms of radiation units, like energy (in SI units of
Watts), and radiance and irradiance - being power (watts)
per unit area (Ie. SI units of square metre (m2)
or in units of solid angles, steradians (sr).
UNITS : Brightness is measured in the SI
units known as lux (lx), as the numbers of
lumens per square metre, which in astronomical terms
is about 0.25 lux for Full Moon, 1 mlx (milli-lux) for dark
moonless night sky, 50 to 80μlx for general
starlight.
The unit of lumens (lm) is more complicated, being
the amount of light (number of photons) emitted by a
uniform source of one candela, that is spread over the
solid angle of one steradian (sr)
The SI unit of candela (cd) is also a measure of
luminosity intersity of some monocromatic light source
(single colour). Few astronomical sources are known to be
monochromatic.
3. The title of much of the earlier section on green stars I have updated, which appeared in the 33-doubles e-group entitled “It’s Not Easy Being Green”.
I commented “; In regards the colour Green, perhaps Kermit the Frog is the only being, in this world, who sees these green coloured stars with certainty? (Hence the title...)”
4. I been thinking of proposing an experiment using a series of stars in increasing Right Ascension, in which the observer has to estimate the colours, and this is later correlated with the B-V values. This will give an estimate of the observer’s ability to see colours, and even shades of those colours. It would also test the colour acuity of the observer, objectively. Would anyone be interested in such a visual experiment?
5. I have some Double Star Colour Estimate results of the seventy-two stars observed by some thirty-two (32) amateurs of the Astronomical Society of New South Wales and other nearby Australian astronomical Society’s. We conducted these, equally among a few northern and many southern pairs. (See Page029d.htm)
6. Luis Arguelles (33-Doubles Communication) commenting on this suggests;
“...as commented by other members of the list, probably it was caused from different cultural roles between males and females. I also think it’s more the question of brain processing of light than the number of cells in our retinas.”
7. Ric Hill (33-Doubles Communication Message 835: 05th April 2000), was the one who inspired some of the text above. However, there is absolutely no evidence to support his quote below;
“Yes, I remember reading that during WW II a study was conducted by DOD, to determine which were better suited for night watch duty. I can’t remember the source, possibly Science News but if it was then it was from the early 1990’s, or maybe the late 1980’s. Basically, it found that women see colour at a lower light level than men but men can see in an overall lower light level than women but it’s all black and white to us. So if you want to see faint galaxies, be a guy. But if you want to see colour in the Orion Nebula, be a gal. Sorry ’bout that folks, nature is sexist.”
8. I have studied chemistry and worked for a biscuit company for some sixteen years before leaving several years ago. During 1989, one of my projects was to the set-up for the instrumental measurement of the colour of baked biscuits. I was already fairly interested in colorimetry sometime before this, and actually once did a specific course on colour including colour matching and design. Yet of the seventeen in the class I was the only male, mainly because they designed the course for advertising, textiles, cosmetics and fashion. A small portion however was left under architectural design, which I enjoyed the most, but I unfortunately missed a few of these lectures. Much of the earlier work presented was on colour measurement (colorimetry) and on the creation and nature of pigments. Once I completed the course, I am now considered a colourist, though over the years I have never called myself this. This is mainly because others have often interpreted the connotations of the title, by me presumably being able to improving there lives by advising matching certain colours to their personalities — the ’astrology’ of the colourist. This knowledge, however, has proved to have certain amusing advantages especially with the opposite sex. Ie. Drumming up a conversation, but I have observed, despite my continued advice, most of them still take absolutely no notice — - and in some ways I don’t blame them! Furthermore, I still continue to wear the “standard issue” black trousers with brightly coloured tops and jumpers - and never as the current and costly fashion dictates. Oh, and to answer the general question about my favourite colour - it is pale aqua blue.
