Astronomy, perspective, opera glasses and a small dog.

A very happy new year to all our readers. We remain unable to get out into the historic landscape but one thing we can all do, on a clear evening, is have a look up at the stars. This and probably forthcoming blogs will be designed to provide some historical inspiration through the night sky.


A consequence of this enforced lifestyle change for many, is enabling those now working from home to look after a dog and many people we know have welcomed new furry canines into their homes. This blog is written with dog owners in mind, particularly those with dogs demonstrating an interest in history, literature and the night sky. But you don't have to have a dog to read it.


During lockdown 2.0 we obtained a copy of Garrett P. Serviss' "Astronomy with an Opera-Glass" published in 1896 (lockdown is responsible for significant increase in old books and vinyl at Travelling History headquarters). Astronomy with an Opera-Glass is a fascinating little book, but to do it real justice, you need a pair of opera glasses. Thankfully Father Christmas duly obliged on Christmas morning.


Under our polluted Bristol skies, our little 2x40 glasses are excellent. You can fit whole constellations into the field of view, familiar stars become brighter and sparklier and fainter stars and smaller often overlooked constellations spring to life. You can fit all your necessary astronomical equipment in your coat pocket next to the poo bags and doggy treats.


Now we are deep in winter, when you take your dog for an evening walk (as your permitted exercise of course) or into the garden before bedtime, cast your eyes southward and you will see the great constellation of Orion and his famous belt. Follow the line of the belt downwards and left a bit and you will arrive at Sirius. Sirius is difficult to miss, it is the brightest star in the entire sky and is the theme of this blog - Sirius, the Dog Star. It is known to us as the Dog Star as it is the principal star in the constellation of Canis Major, one of two hounds accompanying Orion on his relentless stroll across the heavens. In ancient Egypt, Sirius was known as the Nile Star, its pre dawn apparition foretelling the arrival of the annual floods. In ancient China, Sirius was the Heavenly Wolf.


Sirius is bright because it is quite close to us, at just over 8 light years, or 48 trillion miles. It is, from our perspective, quite big, just over twice the size and mass of our Sun. Anybody on a planet orbiting Sirius and looking at Earth through an enormous telescope, or tuning into the radio, right now would be witnessing events of 2013 - what were you doing then?


There is a fascinating story by Voltaire, written around 1750 entitled Micromegas. Micromegas lived on a planet orbiting Sirius, a very large planet as it happened, indeed Micromegas was 22 miles in height. He sets off on some travels and arrives first at Saturn, where he meets a Saturnian, at just 6000 feet tall, somewhat vertically challenged. They then head to Earth where life is so small at first they believe the planet uninhabited. However with the aid of Sirian microscope, eventually they spot microscopic humanity and finally manage a conversation. Perspective and scale are key concepts in much of our teaching and this short story certainly puts many aspects of space and humanity into perspective.


A nice counterpoint can be found in the Hitchhikers Gide to the Galaxy, to quote the great Douglas Adams:


“the mighty ships tore across the empty wastes of space and finally dived screaming on to the first planet they came across - which happened to be the Earth - where due to a terrible miscalculation of scale the entire battle fleet was accidentally swallowed by a small dog."


As the brightest star in the sky, Sirius has been the subject of much study over time and certainly did not escape the attention of the great scientists and philosophers including Aratus, Ptolomy, Horace, Seneca and Cicero. They have something in common when it comes to Sirius - they all described it as being red.


So here lies a mystery. As you can see for yourselves and in our stunning photograph (!) taken from a front garden in Stoke Bishop, Sirius is clearly a bright white star. Our current knowledge of stellar evolution holds that stars evolve from white to red with age and not the other way around and it happens very slowly, (from our perspective of course) over thousands of millions of years. This is known as the Red Sirius mystery. But there we are with the classical written record comparing Sirius to stars such as Betelgeuse, Antares, Arcturus and Aldebaran, the true red giants of our skies. As it happens, even Micromegus describes Sirius as being red to the Saturnian. We have no science to support this change in colour and it seems most likely that a mistranslation or copywriting error is responsible for the anomaly.


So, when you pop out with your dog on a clear winter's evening, dig out your opera glasses and take a look up at Sirius. Contemplate its role throughout history, warning of the flooding of the Nile and the start of a new year. Imagine Voltaire and his 22 mile high Sirians heading this way, or indeed an invasion force whose aspirations of global conquest were thwarted by a hungry puppy. What colour to you perceive Sirius? Compare it with nearby Betelgeuse, top left of Orion, could Sirius really have been just as red a mere 2500 years ago?


Take care everybody and, look out for another instalment of, to quote Douglas Adams once more, our canine guide to life the universe and everything.




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