The brightest comet for a generation put in a brief appearance over the UK in early January 2007. It subsequently swept past the Sun and became a spectacular sight for those in the southern hemisphere. During the close approach to the Sun the heating of the comet's icy nucleus drove off so much dust and water vapour that, in a very clear sky, the comet became visible even in broad daylight. As it rose away from the Sun after perihelion the debris thrown off gave rise to a beautiful curved tail, much more substantial than before close approach.
Before perihelion (closest approach to the Sun) McNaught was observable only low in the east before dawn or low in the west just after sunset, with the evening view becoming favoured as the comet approached the Sun. It brightened rapidly in the days leading up to closest approach but in doing so it became too near the sun to see in a dark sky - in other words, it set before dark, and even when it could be seen it was very near the south western horizon.
I therefore caught it only on two days, 10th and 11th Jan, with conditions on the first day being much superior to the second because the sky was free of clouds and murk almost down to the horizon. It makes a fine sight over the skyline of London, as this photo reveals - unfortunately rather blurred as it was a 4 second exposure taken through my office window by holding a little point and shoot camera against the glass.
For a wider view of McNaught over the London skyline see here.
The comet was visible for about half an hour after popping out of the evening twilight and before being lost behind the buildings of London.
The following day the sky was murkier so I was forced to see the comet higher up but in a lighter sky. I again had only my small camera and used the same office window, though did have a tripod this time so the result is sharper. However, the comet is only faintly visible, towards the top left of the photo, owing to the lighter sky.
Clouds obscured the view for the next few days so it was not until the evening of 14th Jan from rural Devon, and again at around mid-day on the 15th in London, that any hope of a view was possible. By now the comet was only 5 or 6 degrees from the sun, so extreme caution had to be exercised not to blind yourself by catching the sun in binoculars - best avoided by standing so as to hide it behind a building.
It should have been visible in broad daylight, and the Spaceweather archive has pictures to prove it, but despite my best endeavours with binoculars and taking photos of the correct patch of sky, it remained stubbornly elusive! I think that a thin veil of high cloud must have obscured the view and scattered too much sunlight, so it could not be seen against what was already a very bright sky.
At this point though, the brightness was calculated to be around -5, brighter even than Venus, which makes Comet McNaught the brightest comet since Ikeya-Seki in 1965. It certainly made an impressive sight as seen by SOHO, which observes the sun continuously from space - the tail completely overwhelms the image sensors.
After swinging past the Sun, the comet headed south and was lost from view from the UK, but became a fine sight for southern hemisphere viewers as it headed out from the sun back into darker skies.
Just 2 days later Hannah Jackson took this picture from Mt Albert, Auckland, New Zealand at 9:33pm local time on 17 Jan 2007.
Husband Brent takes up the story...
"Finally got a good look at Comet McNaught. It looks fantastic, huge curving tail easily visible with naked eye, and very bright coma. Went up Mt Albert, and took my telescope. A large group soon congregated around us, including puzzled dog-walkers, and joggers, wondering what was going on. I was first to spot the comet through my binoculars, but even with my directions, the others with binos still could not find it until others were already spotting it with the naked eye.
Got the telescope set up, and a constant stream of people wanting to have a look, kept me busy constantly adjusting it for them. Hannah managed to take some good photos, and I did get a good look myself a couple of times. But it was glorious just to look at with the naked eye, hanging in the sky, as though someone had punctured the sky, and light was streaming through it from behind."
With the comet moving into darker skies as it rose away from the Sun another friend in Australia, Michael Mattiazo, captured more pictures that reveal the full extent of the sweeping curved tail. The one to the right is on 22nd January, seen from Henley Beach, a suburb of Adelaide, and the one below is the following day, from Myponga, South Australia.
The tail curved back so far along the comet's orbit that even by the time this picture was taken, it was still possible, from a very dark site, to see the outer reaches from the northern hemisphere. Alas, the skies from the UK were not clear or dark enough for this...
Right: Canon 300D, ISO 800, 90mm lens, 20 seconds.
Below: Canon 300D. ISO 1600, 18mm lens, 80 seconds
Two weeks later the comet was fading fast as it continued to recede from the Sun and Earth. By 9th February it was down to the 4th magnitude in brightness, still visible to the naked eye from a dark site, but otherwise requiring binoculars. Michael's picture below shows it looking much like any "normal" comet would - a fine enough sight but hardly satisfying after what had just come before.
Location: Two Wells, South Australia. Magnitude 4.3
So goodbye to the comet of a generation...
For further pictures visit Michael's Southern Comets website or the Spaceweather McNaught archive.