Well, the eclipse yesterday was fun. There were enough patches of sky between the clouds to get some good views. I was pleased that the pinhole cameras I made out of miscellaneous cardboard tubes, tins, paper and tinfoil worked really well. Also, the trees around the front of the sciences building gave some nice natural pinholes as the sunlight worked it’s way through the gaps between the foliage – we could see lots of crescents projected onto the wall of the building. Not something you see everyday.

The trick with the pinhole camera is to get the combination of length between pinhole and screen and size of pinhole correct. (Basically – the f-number in photography-speak) A long length means a larger image – but also a fainter one. To increase the brightness, we need to let more light through (a bigger pinhole) but the drawback of this is that it blurs the image. It takes a bit of experimenting – best done well before the eclipse that you want to see.

On the subject of which…if you live in New Zealand…you don’t have a lot of opportunity for a while. We northerners get an iddy-biddy eclipse next May (10th) – sorry Mainlanders – you miss out – and then it’s nothing for ages before we get a few more feeble partials in the 2020s. BUT, as I said earlier, it’s then non-stop eclipse mayhem from 2028, with THREE total and THREE annular eclipses before 2045, for those of us who are still alive to see them. Details are all here courtesy of RASNZ.

There are a few videos up already from the Cairns region – here’s one. However, video does not do an eclipse justice, partly because of the difficulty in video capturing parts of the corona at different luminances simultaneously. If you want to see the fainter, whispy stuff at the far edge of the corona, you end up well overexposing the brighter area nearer the moon.  The naked eye does a far better job of capturing the totality phase than a camera. 

http://www.youtube.com/watch?v=CTbIufApsSk

I note a fair amount of pink on the video – this is the chromosphere – a thin, cooler area of the sun, between the photosphere (the bright yellow bit that we normally see) and the corona.

I haven’t read ALL of Tolkien’s work, but I suspect space-travelling hobbits don’t feature anywhere. However, what do feature are hole-dwelling hobbits, and I had the fun of seeing their holes in the countryside near Matamata yesterday. The original set for Lord of the Rings was mostly removed after filming, and rebuilt for the filming of the Hobbit trilogy.  (Trilogy? Since when was The Hobbit a trilogy? This is just milking money out of Tolkien fans, isn’t it?) But this time the set will remain, for all to see, for an appropriate fee of course. It certainly was fun to have a look around – what made it was the commentary provided by our excellent guide.

One of the fascinating things pointed out was the perspective tricks that were used. For The Hobbit, there are three different versions of some of the holes.  One, a ‘large’ version, appropriate for a normal-sized actor, dressed as a hobbit, to walk through. One, a smaller version, to make the dwarfs look bigger than the hobbits. And another, an even smaller version, to make Gandalf look bigger than the dwarfs. And the three had to be identical.

And then there are the perspective tricks. To make the view look like it is over a longer distance, the more distant holes are of smaller size than the nearer ones. On a 2d movie it works – your mind interprets what you see as being of equal-sized holes spread over a larger distance. But being there in 3d you see it more as it is.  

That’s the problem that’s faced when determining the distance to distant stars and galaxies. Just how far are they away?  The moon, and anything further away, we perceive as 2 dimensional. We can’t get any 3-dimensional cues and so we have no idea, just by looking, of how far away they are.  So how can we measure distance to the stars? 

One way, which works for the nearest stars, is parallax. The earth orbits the sun, and six months from now it will be about 300 million km away from where it is now. That gives a different viewpoint. The nearest stars, therefore, appear to move against the background of stars that are further away. We can therefore use a bit of simple trigonometry to work out the distance to the star. Indeed, one of the units of distance in astronomy is the parsec – one parsec being the distance over which the diameter of the earth’s orbit subtends a parallax angle of one arc-second.  Essentially, using parallax in this manner is like viewing the situation with two eyes – 300 million km apart.

Parallax, however, only works for our nearest stars, since the distances to our neighbours are so huge. To work out distances further away, there are other methods – such as looking at the intensity of Cephid Variable stars, and, for really long distances, the famous redshift. However, somewhat disappointingly, neither of these are exemplified by the Hobbiton movie set.

Well, if I knew that I would be busy doing it. Perhaps you’d be better off asking Perlmutter, Schmidt and Riess who have just won the 2011 prize for their discovery of the ever accelerating expansion of the universe. I love the story I’ve heard (whether it is true or not I don’t know) that, on receiving the phone call from a woman with a Swedish accent, Adam Schmidt at the Australian National University assumed it was a prank from some of his graduate students.

It’s worth a note that while I was an undergraduate, there was still a lot of debate in cosmology as to whether the universe would expand forever or start contracting again – the data available at the time suggested it was close to the critical point between those two options. Not any more.

There’s been a bit of a theme (or two themes) to the Nobel Prizes for physics in the last few years (by which I mean since about 2000). You can split them into two roughly equal groups: (i) Materials (e.g. graphene, giant magneto-resistance, superconductors…) and (ii) Particle physics and Astrophysics (expanding universe, symmetry breaking, microwave background…). Maybe that’s three groups. If you want your prize, those two/three areas seem to be the places to be in. No hope for me then.

The one that stands out as not fitting in with the themes is Glauber / Hall & Haensch’s prize in 2005 for optics, including in Hall and Haensch’s case the development of the optical  ‘frequency comb’ for precision spectroscopy.

An interesting point is that the prizes in recent times are roughly evenly split between those in extremely practical things (often that have changed modern technology and made a lot of money, such as integrated circuits) and those in ‘blue-sky’ things, that have less obvious application. Physics covers a huge spectrum (if I can use that optical word) of research, and the practical stuff and blue-sky stuff both form a part of it. It’s nice to see that both are being recognized in this way. Governments take note.