Day 16 – Monday Evening 20 January.
By Grant Chapman
It was Lorraine and Grant’s turn to be on watch for the graveyard shift and they resolved that they would try and identify some of the stars that were making their steady progression across the night sky, considering that Grant was busy learning his celestial navigation during the voyage. With only the occasional slurping sound of the water under the hull to disturb the peace and all the lights on board switched over to the red night lights, save the navigation tricolor and windex light at the top of the mast, providing minimal light pollution, the conditions were ideal to become acquainted with our place in the vast galaxies above us. Grant retrieved his various almanacs and set about trying to find the planets and stars he needed to perform his various calculations in order to locate us on the surface of the earth. With exotic sounding names likeAldebaran, Markab, Al Na’ir, Miaplacidus and Hadar the sky was certainly an enchanting place with many of the stars having received their names centuries ago, their names revealing which distant lands the respective astronomers who first discovered them hailed from. Some stars, like Canopus with a declination of nearly -530 (declination or celestial latitude is its angular distance north (+ve) or south (-ve) of the celestial equator) have more contemporary names as being deep in the southern hemisphere’s sky they were not visible to all the early astronomers in the northern hemisphere whom we have to thank for advancing the science of astronomy all those years ago. The constellations of Centaurus and Canis Minor, on the other hand, already formed part of Ptolemy’s 48 constellations over 1800 years ago. As much as the earth together with its sister planets in our solar system rotate around the sun of course and the stars in other galaxies in our universe have their own paths to follow that are unrelated to the inconsequential planet we call home, for the purposes of celestial navigation one has to consider that the earth is at the centre of the universe and that everything else in the universe rotates around us. The distances to stars in other galaxies are so huge, mostly measured in hundreds of light years, that the “earth at the centre of the universe” model works for all intents and purposes and the fudge is forgiven, allowing us to indulge ourselves for a while as we hark back to the days before the likes of Copernicus, Brahe and Galileo who were ridiculed and persecuted for advancing the case for at least the sun being at the centre of our own solar system. So distant are the various bodies in our universe that gazing into her depths is like looking back in time many millennia in our very own time machine when life as we know it never existed.
Before she disappeared below the horizon we spotted Betelgeuse dead ahead of us over Rotary Scout’s bow, a massive “red supergiant” star in the Orion constellation that is 950 times the size of our own sun. If we had Betelgeuse at the centre of our own solar system instead of the sun her surface would extend as far as Jupiter’s orbit, swallowing up Mercury, Venus, Earth and Mars. Approximately 640 light years away it is possible that she has already become a supernova, collapsing into a black hole with such an event only being witnessed by us on earth some time in the next couple of hundred years. Our next sighting was Sirius (the “scorcher” given her brightness) just off our port bow and about 150 above the horizon. The brightest star in the night sky with a magnitude of -1.46 (rather strangely, the smaller the magnitude of a star the brighter it is with negative numbers being super bright – no doubt the boffins in the business of working these things out have a good reason for this as such logic totally escaped us mere mortals busy being captivated by the awe of the heavens above us). Next we found the Southern Cross with her two pointer stars – Alpha and Beta centauri, also known as Rigil Kentaurus and Hadar respectively. Both of these “stars” are actually binary stars, a fact that is indiscernible to the naked eye. Aslo, although the pointers may look similar, Hadar is far more distant than Rigil at 350 light years away compared to Rigil’s relatively proximate 4 light years away. Just as we started picking up our own solar system’s planets Lorraine spotted a shooting star and then very shortly afterwards pointed out a bright object that was making its way across the sky and quite a pace – not fast enough to be a shooting star and yet far too fast to be an aircraft. We decided that it must have been one of man’s satellites that had been placed in orbit above the earth, possibly even the International Space Station. At a typical altitude of 500-750km above earth’s surface, unlike the geostationary satellites we rely on so much for our GPS gadgets these days, research satellites such as the Japanese Akari and Alos, EU Envisat and US Hubble Space Telescope and SEASAT (now defunct) appear to race across our sky as it is planet earth that is doing the moving as she rotates at an incomprehensible 1600km per hour. Such research satellites are used to determine all manner of useful data on the oceans, atmosphere and land, helping to predict hurricanes, tsunamis and even earthquakes among other natural phenomena our planet is subjected to.
We ticked off the four planets that are useful to celestial navigation as we sighted them, being Venus, Mars, Jupiter and Saturn – the others in our solar system being to feint to identify by the naked eye. All of the planets exhibited a reddish glow, unlike the twinkling stars, with Jupiter the most impressive, high in the sky to the north east of us, outshining even the stars in her near vicinity. We located Venus close to the moon which was waning gibbous. The moon presents her own set of complexities when using her for navigation purposes, owing to her relatively close proximity to earth at only 384 000km away resulting in errors of parallax and various other corrections to declination needing to be corrected for, as well as consideration for what part of the moon one is using for a sighting. To the careless the moon can be a nuisance to use for sightings but with the right discipline she is an asset, being visible more often than any other celestial body, including the sun when it is overcast most of the day and clears at night. The moon is also a seductress as eons of navigators would attest and should be given the attention she deserves as she perpetually hides her dark side from mankind’s view in her perfect synchronicity of rotation with earth’s rotation.
Before we knew it the new watch for the night appeared from below decks and it was our turn to retire for the night after a fascinating journey through an infinitesimally small part of our inconceivably gigantic universe and what must have been the fastest 2 hour watch we had experienced on our voyage thus far.