Practical astronomy with an almost-seven year old?
Spent some time with nephew-nearly-seven over Christmas and - despite the lure of lego ninjas and talking dinosaurs - he was quite happy to join me outside on a clear and frosty night. I started off by showing him a few landmarks of the sky - the Milky Way, most prominent stars and recognisable constellations - using a laser pointer to trace out their shapes. (After first explaining the importance of checking for aircraft, to avoid dazzling them. He certainly made a conscientious air traffic controller, for the rest of the evening I couldn't go near the the laser without a warning, including for planes fifty miles away and in the other direction.) Resting on the Pole star I tried to explain how the stars appear to rotate around it, as shown in the time-lapse video below.
Video by James Castelli, Cherry Springs, Pennsylvania - Aug 2008
Next we had a go at astrophotography, I set up a motorised tracking mount and attached a camera with a wide lens. I pointed the camera in roughly the right direction and disengaged the clutches so he could gently nudge it on to target. After a couple of attempts he got this shot of the Milky Way with a 2 minute exposure.
After this success I thought I'd see how he got on with a longer lens and higher magnification. The Andromeda Galaxy, our nearest large neighbour, was well placed and easily visible to the naked eye, I showed him how to find it by star-hopping from the easily found starting point of Cassiopeia. By resting the laser pointer on top of the camera I was able to show him where he was pointing. Some persistent nudging and another 2 minute exposure gave this result.
A cropped and centralised version shows the structure of the galaxy more clearly. The dust lanes, spiral structure, bright core and even the star cloud NGC 206 can be made out, as well as the two orbiting satellite galaxies, M32 and M110.
It's interesting to compare the above with this groundbreaking photograph, taken by Isaac Roberts in 1888.
At one time astrophotography was thought to require expensive equipment, exacting patience, careful experimentation and a beard. Now it seems none of those things are strictly essential but modern astronomy is built on the efforts of pioneers like Mr Roberts, and countless others.
To wrap up our session I tried a quick portrait shot, with unexpected results. I put the camera on a fixed tripod and took a 30 second exposure.
I asked him to flick his torch up and down, turn it off and then run out of shot. In the process I accidently created a sith lordling, not exactly the dark side I was hoping to turn him to. (If I'd asked him to move to the side and do the thing with the torch again there would have been an evil twin in the picture - there is lots of scope for trick photography when taking long exposures at night. Maybe creating a nephew-horde or a lightsabre duel will be a project for next Christmas, I'll have to ask him.)
And who knows what he might have discovered if it hadn't then been bedtime?