Everybody said that Comet ISON, or more exactly C/2012 S1, would be either the comet of the century or a complete dud after it would swing around the sun. The comet had even reached naked-eye visibility in the last two weeks and there were a lot of amazing photos taken by astrophotographers around the world, but then came the initial disappointment: yesterday the comet reached perihelion, the closest approach to the sun at about 18:45 UTC and at first it seemed like it had not survived its first and perhaps only trip around it.

NASA had broadcast a two-and-a-half hour hangout during the event, because thanks to the Solar and Heliospheric Observatory, the Solar Dynamics Observatory and STEREO satellites it was possible to monitor the comet’s approach and departure practically in real-time – and very soon it seemed like the comet was simply going to fizzle out. Even before it had reached the sun, the tip became smaller and smaller, like the nucleus had already broken up. Phil Plait, the Bad Astronomer, who participated in NASA’s webcast, was the first one who reluctantly and sadly agreed that Comet ISON had probably disintegrated and when the webcast ended after nothing had emerged on the images from the satellites, everyone thought it was the end of ISON and went to their Thanksgiving dinners.

But then something amazing happened: the comet made a reappearance, as you can see on the image above – at first everybody thought it was only the remnants of its enormeous tail, but then the comet, or what was left of it, suddenly brightened more and more. For the full scoop, I can recommend Elizabeth Howell’s Article on Universe Today called Zombie ISON ‘Behaving Like A Comet, Stunned Astronomers Say’ which sums up the current situation very well. Phil Plait also has a great post on his blog up and Emily Lakdawalla has even more animations and images in her article! The bottom line is that nobody really knows yet what Comet ISON is up to and it may even be possible that it will be visible in the skies in December after all. All that remains at the moment is to wait, to gather data and to figure out what is going to happen to ISON. And this is the part scientists especially love: ISON is a great challenge, sporting a behaviour that has not been seen before. [Update 4.12.: Well, it seems ISON has fizzled after all, but it had put up one hell of a fight – it’s still to early to say if the remnants will be visible at all, but it doesn’t look too good.]

While Comet ISON has after all not turned out to be a turkey, the second launch attempt of the SpaceX next-generation Falcon 9 rocket to transport a communications satellite into a geosynchronous transfer orbit at 80000 kilometers from from Earth, certainly has. The first attempt on Monday had already been scrubbed because of technical problems and the Thanksgiving launch had an even more spectacular abort: the engines had already fired when the launch sequence was automatically aborted because the system had detected not enough thrust buildup. A second attempt was also scrubbed because the engineers did not have enough time in the launch window, after that it was decided to bring the whole rocket down to inspect the engines. But this is not a catastrophy, quite the contrary: SpaceX is being deliberately careful and this shows the company’s competence. This is rocket science, and it’s not easy. As Elon Musk said in his tweet shortly after the abort – better to be paranoid and wrong! [Update 4.12.: The caution has paid off, yesterday SpaceX launched the rocket successfully and put the satellite on board into the required geosynchronous orbit without problems!]