A night in the life...

...of your typical Mauna Kea astronomer. I know many people are interested in exactly what we do on the mountain, so thought I'd provide a brief description of a typical day.

The "day" usually begins at around 3pm when the alarm goes off. I'll get up, take a shower and log on quickly to check the latest planetary alignments, ascendants and conjunctions on the numerous professional sites around the world. It'll give a good indication of the type of observations we need to make during the upcoming night. I then join all the other observatory staff at the Hale Pohaku dining room for dinner at 4pm although it really should be breakfast for us night owls. We'll discuss the position of the planets, what constellations they're in, how they're affecting our current lives and often argue about the influence that the moon and sun have on current politics. Retrograde motion and its link to the current recession is a particularly hot topic these days.

There's been a nasty rumour going around recently that the tables are segregated according to one's zodiacal sun sign, but I can assure you that's nonsense. Do you really think we'd allow a bunch of Geminis to sit together at one table for instance? They'd never leave for work with their constant chatter. Leos would be comparing their egos - imagine the chaos that would cause. No, we're a fully integrated group and encourage mixing and mingling at the tables, although when there are those rare and powerful planetary alignments we're a little more circumspect about who sits with who.

At around 5:30pm we all head up to the summit and to our various observatories. At this time of year the sun sets at around 6:45pm and we need a few minutes to measure the sun's position. It can be a little embarrassing to publish positions only to find out a day later that we thought the sun was approaching Aries when in fact it was solidly in Pisces, so we do our best to avoid those kind of mistakes.

At approximately 7:30pm the sky is dark enough to observe properly, and we spend the next few hours using a powerful survey camera to measure the positions of the constellations. If we need to confirm the identity of a particular star (it can be surprisingly difficult to do that at altitude with so many other stars visible) we'll switch to a spectrometer and identify it via its infrared spectrum.

This takes several hours to do because there's a large amount of sky to cover. We usually complete this task just after midnight, but if the moon is up it might take longer as we have to measure its position regularly. Compared to the stars the moon moves quite quickly, so it takes several measurements to determine its mean motion across the heavens.

So, typically by 1 or 2am we have the data we need and can plug them into the supercomputers every observatory has at the summit. After another hour or two they'll spit out the results which typically look like this:

At this point, around 3 to 4am, the circadian rhythm combined with our 14,000-foot altitude really kicks in and it's hard to stay awake, let alone think clearly. This is the best time to write the following day's sun-sign horoscopes for the newspapers so we'll spend the next hour doing that. During this time we allow the telescope to track a particularly attractive deep-sky object so we can send a nice image to newspaper science editors all over the world as well as the Astronomy Picture of the Day website.

By the time all that's done it's sunrise, so just a few more observations of the sun's position are made, a quick calculation using its current position and that measured at sunset is made and we can send off our prediction about the time for sunset tomorrow. The same measurements and results are sent in by all the observatories so a very good average can be made and all the various weather sites around the world will have accurate sunset and sunrise times for the next day.

Then it's back down for breakfast, a quick check of the early morning newspaper horoscopes as they should have our predictions in by now, and off to bed.