When I was five or six years of age, I was fortunate enough to look through a telescope and gaze upon Alpha Centauri. This immediately revealed two very bright stars, appearing like two bright car or truck headlights at some distance, daintily painted against the velvet-blue backdrop of the city skies. My imagination was directly sparked. These two stars were genuinely surprising, and to make sure it was not an illusion, I looked along the telescope tube to see one solitary star, and from that time on I was hooked to “up there”. This interest became even more important in my later astronomical adventures when I had my own telescope and began observing double stars.
I recall many wonderful inspirations, but the best story involves travelling to New Zealand for the 1984 Royal Astronomical Society of New Zealand (RASNZ) conference. On my arrival in Wellington, which is located on the southern tip of the North Island, I was picked up by my friend at the airport. He told me he was scheduled to be the night guide at Carter Observatory for the usual public viewing night, and persuaded me to come along. If you do not know Wellington, Carter Observatory is located within the Botanical Gardens, on the steep hills directly above and behind the commercial business district of the city of Wellington. You can still catch the cable car up from the middle of the city to the base of the observatory. Quite a unique experience! As New Zealand’s first National Observatory, the main telescope is an elegant 19th Century 23cm equatorial refractor, mounted on a good solid equatorial pier. The tracking was excellent, based on a gravity weight drive that had to be manually cranked-up, but this has now been converted to using, and far less romantic, to electrical power.
I also remember my astronomical friend making some excuses about a minor problem with the telescope drive. and kindly asked if I would act as the night-guide for a moment or two. Today, I still don”t know if it was an excuse for a break, but in a short time, a little boy, perhaps seven or eight came along with his father. Carefully he began to climb the twenty-odd steps into the observatory dome and looked amazed at the size of the telescope. The father of the boy explained that his son wanted to look through the “big telescope”. I recall they were not too sure of me because of my Australian accent, but astronomy is astronomy, so this insecurity quickly passed.
The northern part of the sky had inconveniently become covered by some very heavy cloud. I disabled the right ascension lock and directed the telescope towards to the southern part of the sky. Selecting Alpha Centauri, I noticed that the sky towards this direction was very bright, as the telescope was pointing directly above the city. In moments, I had the finder centred on the star and glanced quickly through the telescope to see that the finder alignment was true. The field was vividly sky blue from the lights of downtown Wellington below, and this field reminded me of sketches that we sometimes see in old astronomy books. The images of the two stars were suffering dreadfully from poor seeing conditions, but they did indeed look like incandescent searchlights. Not forgetting the “customers”, I invited them to look. For any adult, the telescope was at a comfortable height, without the need for bending or even “tippy-toeing”, but the boy was far too small. His father picked him up gently by placing his hands under the boy’s arms and then guided him carefully towards the eyepiece. “What do you see?” I quietly asked. “I see two stars, and they are really large and really bright”, he enthusiastically replied. His dad put him gently down to have a look himself, and I began speaking to the boy’s father explaining what he was looking at.
I had not noticed at first what the small boy was doing, but when I did, I can still visually picture the very rare sight of this little boy being literally “star-struck”. He was simply sitting on the observing stairs, at one corner of the observatory, with his elbows on the knees and his hands angelically open under his chin. His one comment was simply perfect “Wow!”. Instantly my mind flooded back to my own first experiences. I imagined, and hoped that the boy”s personal path along the “starry path” would soon follow mine. Moments like these cannot be forgetten.
My own discoveries occurred in the year that I first started reading astronomical books. I found that this star was the closest to the Sun, as stated in nearly all introductory astronomy texts. What did happened 4.3 years ago? The mind was simply lost. More revealing, at least to me, was that the two stars were in an actual orbit, travelling full-circle in just under eighty years. This was just like the planets in the family of the Sun, and all other astronomical bodies, each under the eternal dance of the universal force of gravitation.
By the age of thirteen I had my own 7.5cm reflector. Its “first light”, as in all my subsequent telescopes, has been Alpha Centauri, followed by other pairs like Alpha and Gamma Crucis and the Jewel Box. I cannot recall the apparent positions or distances of the stars during my first few observations, but by 1971, I was old enough to understand - the pair was approaching maximum separation of just over 22 arc seconds. From 1971 until about 1995. the position of the apparent orbit has changed little in the pair”s telescopic appearance. A serious observer, recalling the background field stars, could possibly pick up these small changes, however, I admit I still have trouble discerning serious differences in the orbit. At the dawn of the 21st Century sees notable changes and now I do see the changes.
Over the next few decades Alpha Centauri will undergo dramatic and obvious changes, producing significant problems for those with both small and large telescopes. Twice, within fifty years, the familiar pair will almost merge into an evidently single star.
I have even dreamt about peeking at Alpha Centauri when it was much closer together, but looking at this pair every now I have proven (with my own eyes) that I have seen a binary star in action - something that is a illusion because sometime must pass before this can be seen for yourself.
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