Win Kent author's book The Rainbow Sky
PUBLISHED: 17:06 29 October 2010 | UPDATED: 18:05 20 February 2013
Ever wondered what the dark band between a double rainbow is, why a star that appears to be red is a 'cool' star and just how to capture fireworks on camera? Author Tony Buick from Orpington reveals all
Win Kent authors book The Rainbow Sky
Ever wondered what the dark band between a double rainbow is, why a star that appears to be red is a cool star and just how to capture fireworks on camera? Author Tony Buick from Orpington reveals all
One of the atmospheric natural delights is the stunning and unannounced arc in the sky that is the rainbow. The colours are always in the same order and, if recombined, will always produce the original white, as discovered by Sir Isaac Newton.
Have you seen a double rainbow and noticed a dark band, The Alexander Band, between the two? And can you explain that? Bows come in many guises: fogbows, ground bows, moon bows and more.
Next time you are in an aeroplane look below at a point directly in line with where you are sitting and the sun. You will see a circle of colours called a Glory, with a shadow of the aeroplane in the centre that gets bigger as you descend towards the cloud.
A similar phenomenon is a Brockenspectre that appears in ghostly form often when looking down from a hill onto a blanket of fog. Without knowing the cause of the apparition, it can be a frightening experience.
Although common, a spectacular sunset always generates a wow. But do you know why the colours appear? Same reason as why the sky is blue, its the Rayleigh Scattering, where small particles in the air interfere with the similarly sized wavelengths of light.
Many atmospheric phenomena can easily be photographed by anyone with an off-the-shelf camera, especially with a little guidance on technique. Some take a bit more know-how, such as photographing the ephemeral flash of reflections from the panels of the International Space Station and Iridium Earth satellites.
The next step, peering through a home telescope, reveals the wondrous and colourful collection of planets in our solar system such as red Mars and turquoise Uranus. The sulphur hues of Jupiters moon Io require the larger professional telescopes.
Beyond our solar system, photographic capture of deep-sky objects becomes more difficult. Many of the bodies are invisible to the narrow wavelengths of light that our eyes can perceive, but telescopes on Earth and in space now have the capability to observe emanations of other parts of the electromagnetic spectrum (the complete range of radiation of which light is a small part) such as X-rays and infrared.
To allow the human eye to then appreciate the images computerised, manipulation is required to convert those photographs to the reds, greens and blues for us to appreciate.
NASA, ESA and other administrations constantly bombard us with beautiful and amazing images but remember, they are all false colours or, at best, a simulation of what the human eye is likely to see.
Some of the most colourful and spectacular space pictures are nebulae, huge gaseous masses the result of gigantic explosions of the stars. Our own star, the Sun, will explode in around five billion years to produce colourful remnants and exterminate any last vestiges of life that may remain after a possible plethora of Armageddon events during our Earths future history.
Amazing as the space images are, the objective for professionals and serious amateurs is not just to fill a gallery with coloured pictures! In fact, the study of the colours, spectroscopy, is the only reason that we know anything about the objects in the universe outside our immediate space environment and we know a lot.
There is a huge amount of information in the images captured. If a star appears to be red then it is a cool star, such as the giant Betelgeuse (Alpha Orionis) at around 3,500C in the constellation of Orion.
Towards the other end of the scale, blue Rigel, also a huge star in Orion (Beta Orionis), is hot at around 12,000C. If a star appears to wobble then it is probably close to another object, possible a planet. The extent of the wobble and alternating brightness provides information on the size and type of planet and is the basis for seeking planets that may harbour life as we know it.
Have you noticed the twinkling of the star Sirius close to Orion? It flashes through the colours like a beacon that may be recorded using your family compact camera. The twinkling (scintillation) is due to refraction through the Earths atmosphere, especially noticeable when the object is close to the horizon, resulting in the light passing through a greater amount of air.
The Rainbow Sky covers not just cosmic and galactic colours but also man-made ones and, in some cases, how to photograph them.
Fireworks are especially spectacular when captured by camera and its easy when you know how. It is not necessary to understand the theory and history of light and production of the characteristic colours generated by different chemical elements, but brief and easily absorbed fundamentals are included for those who wish for an introduction.
Most of all, the next time a magical sky display suddenly confronts you. be it an intensely coloured rainbow or an overwhelming red blanket of a sunset, enjoy the moment and maybe, just maybe, reflect on the majesty of the spectacle and know that they are fine examples of the multi-coloured universe in which we live.
Kent Life is giving away five signed copies of Orpington-based author Tony Buicks The Rainbow Sky: An Exploration of Colors in the Solar System and Beyond, with a foreword by Sir Patrick Moore. Published by Springer, it retails at 22.99.
To be in with a chance of winning, just answer the following simple question:
Q: What are the colours of the rainbow, in sequence?
Send your answer to:
The Rainbow Sky
West Sussex BN11 1UG
or by email to: firstname.lastname@example.org
Closing date for entries: 30 November 2010.
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To contact Tony Buick, email: email@example.com