Tuesday, 6 March 2012

Observing Comet Garradd (C-2009/P1)

The Gemini North telescope at the Mauna Kea Observatory, Hawaii

March 6, 2012

The summit of Maunakea is a cruel place. At 4,200 metres it is cruel because it is cold and sometimes very windy. But it is super-cruel because it can tease you - just above the telescope the sky can be clear with wonderfully bright stars; at the telescope itself it is too windy to open the dome and there is ridge cloud that makes the air too humid and the chance of ice forming on the telescope mirror to great to take a risk. After all, the telescope cost $90 million, and you can't take risks with that.

Oh, and I haven't introduced this properly yet.

So, I am at the Mauna Kea observatory in Hawaii with the purpose of observing Comet C-2009/P1 Garradd. This was the first comet discovered in 2009 and was thought to be on a "normal" periodic cometary orbit which would bring back close to the Sun from the icy depths of the Solar System at regular intervals. It might even have been round before it was discovered. Not so.

Garradd, which is recently past its closest approach to the Sun and just past its closest approach to Earth, is a one off. It has spent the last 4.5 billion years in what is known as the Oort Cloud, 50 thousand times further from the Sun than is our home planet Earth. Something in the environment of the outer Solar System gave it a kick and sent it crashing in towards the Sun. But it's not coming back - when the orbit was recalculated after the first discovery it was found that once past the Sun, Garradd would be hurled out of the Solar System altogether, never to be seen by humans again - or not until we get really good at space travel and surviving off-Earth for generations at a time.

Steve(left) and Bob (right) in front of the 8-metre diameter main mirror of Gemini

That makes the four nights that my colleague Bob Barber and I have been awarded on the Gemini North telescope very precious. We are here to work out how much water and ammonia the comet is giving off. Because Garradd is essentially a pristine relic of the early Solar System, finding out how much of what it has in it provides important clues into just what was in the cloud of gas, dust and ice that formed the Sun, the planets and everything else in our local space neighbourhood.

But the weather at the summit is just not cooperating, and we are closed up. And the prospects for tomorrow are not much better. Indeed, we may even get snow. The temperature outside is -7 degrees centigrade, and the wind speed is over 100 kilometres per hour, so if we do get snow there is a danger that the whole summit will be closed off. Doesn't someone up there know that if we miss this chance to view Garradd, it's not like waiting for the next bus. It's now or never (cue Elvis).

Maybe the weather forecasters are wrong and tomorrow will be better not worse. So here's a rainbow of hope over Hilo Bay, where Bob and started out from yesterday afternoon. More tomorrow, then, I hope.

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