Message #11003

[martinastro]

''Back in July of 1994 I recall the excitement in the media and within the Astronomical world about comet Shoemaker-Levy 9 which was about to slam into mighty planet Jupiter, it was a monumental event which deeply captivated me at the time. Back then I had a growing interest in Astronomy, however I knew absolutely nothing about the subject, nor did I even know that Jupiter was visible in the sky. I vividly recall the exciting television programmes showing the latest images of the impacts and the live reactions from Scientists all over the world. Among these were the comet's discoverers, David Levy, Gene and Caroline Shoemaker. Many observers the world over marveled at those huge impact bruises on the planet's atmosphere - it was the sight of all sights, a violent and rare event of epic proportions which I never got to see. It was said to have been a once in a life time event and unlikely to be seen by human eyes again. Several years later I got into visual Astronomy in a big way. Comets became my passion, and for me there was nothing more sublime than a great comet in the night sky, in my opinion they are the finest transit event in the heavens. My interest in comets naturally led me into the field of comet impacts on Earth and the search for new visitors, a passion which many amateurs take up, often obsessively, in the quest for making a discovery of their own. During my research it was only a matter of time before the names of David Levy and the Shoemakers arrived back in my life again. They quickly became a source of inspiration to me. Naturally one cannot read these names before the name of Shoemaker-Levy 9 quickly appears. I began to read everything I could about this comet impact, buying books, magazines, documentaries, and listening to radio programmes to learn as much as I could about that incredible event. In truth I was envious of all those amateur observers who seen the impact scars through their telescopes, and as a comet lover I felt that I had missed out, and statistically it should never happen again my life time.

15 years later is has happened again!. When I first heard the news about Anthony Wesley's discovery of an impact scar on Jupiter I couldn't believe my luck. This was unbelievable, a comet has yet again struck Jupiter, this has got to be one of the biggest astronomical events since 94. This was an opportunity not to be missed so I made it my goal to see this impact for myself. Thanks to Dave Grennan I acquired a list of the transit times of the impact scar so it was just a matter of time to catch it in the act. This is not as easy as it sounds because one needs a clear sky with Jupiter at a reasonable altitude, and besides, due to the planet's rapid 10 hour rotation there was only a slight window period when the impact would be visible on the planet at night from Ireland. The best time to see the scar would be when it was located on the centre line of the planet, in other words, on Jupiter's meridian. The first meridian crossings were clouded out for me which was disappointing, however I used the time wisely on other clear nights when the impact was not visible. Jupiter is my favourite planet in the solar system, I cut my first 'sky teeth' on this planet and it was with it that I had learned to observe fine detail through a telescope. There was a time when I knew it intimately. Over the years my observing interests evolved and I found myself being drawn to wide field low power comet observation, so I had neglected Jupiter. With this in mind I decided to begin a relentless observing programme since news of the discovery was announced. I spent hours on every clear night observing the planet in order to train my eye to detect delicate detail at the limit of vision. It was time and effort very well spent.

The next transit crossing was on the morning of the 25th at 02.07. I had the 8.5" F/7 reflector set-up hours earlier so it would cool down to the outside temp and reduce internal thermals within the tube which could hamper observation. I began my search for the impact at 01.00. I switched between two old eyepieces, a 12mm and 9.7mm, which offered a narrow FOV and a poor view. In fact, the eyepieces have become tarnished over the years which was a major handicap. It was however a glorious dark clear night without a cloud in the sky. Jupiter was a brilliant object low in the E within the stars of Capricornus. The view through the scope was not encouraging due to very poor seeing conditions. All I could see where the two Eq cloud belts and nothing else. I stuck with it and never took my eyes from the eyepiece. Gradually, min by min, Jupiter climbed higher into the sky and eventually the rotating Earth threw the planet into a favourable position at a decent elevation. Now I was getting periods of good seeing which produced brief but spectacular views of the planet's belts, zones, festoons, and the four Jovian Moons which where set in pairs on either side of the planet. With averted vision I got blurred glimpses of the impact. At the start it was unimpressive and very difficult to see, however as the atmosphere steadied further I got a rich train of perfect views of the scar which completely blew me away. The impact was dead centre on the meridian and seemed bold and alien as it begged for attention from the south polar region. I seen it as a large well-defined dark smudge, clearly the darkest feature on the planet. With relaxed breathing techniques I oxygenated my blood which improved my vision and by doing this I could see not only a splotch but a striking elongated feature extending from the central area to the E side of the FOV. I checked my watch, it was 02.07 on the dot. I was utterly amazed by the scene, it was breathtaking to see a comet impact scar on another planet...the sight of all sights!. I looked up from the eyepiece and was amazed by a phenomenal black sky with glowing Milky Way crossing the zenith and down into the rich star fields in Sagittarius and Scutum. Behind me to the N was a glorious low level Noctilucent Cloud Display which was beyond words, the skyline was glowing intense yellow-gold which cast shadows. The NLCs looked like a volcanic eruption or impact event itself had occurred on Earth further N. What an incredible soal-satisfying experience. Now as I write this I can see those glimpses of the impact scar in my mind's eye, these will be memories which I will cherish forever!''