The cattle grid in Glen Nevis

Last week we sat on the slopes of Ben Nevis looking down on this cattle grid.  Our seat was near the top corner of the isolated patch of woodland in the picture.  We noticed that there was a big time delay between seeing the car hit the cattle grid and hearing the sound.  I timed it.  Now is that sad?  Anyway, the values were 2.74 and 2.61 seconds respectively.  If we assume the speed of sound in air to be about 335 metres per second, then that means we were sat about 90o metres away. To read about the way in which air temperature affects the speed of sound, try this Wikipedia link: http://en.wikipedia.org/wiki/Speed_of_sound

If you go to The Sky At Night TV programme website http://www.bbc.co.uk/programmes/b006mk7h and scroll down, you'll find the April Moore Marathon Observing guide. It lists 55 things to look for to celebrate 55 years of the programme. My telescope is not for stars but I took this photo of the Moon. 3/4 of the way up on the left hand side, there a small dark crater in a lighter band. This is the crater Plato, one of the 55 objects. The section around it is called the Alpine Valley, another of the objects.

The Sky At Night

The Sky At Night is the longest running BBC TV programme, I think. I've never managed to stay up late to watch it, but the website is good, and of course it's on the i-player now. There are even repeats on BBC 4.
http://www.bbc.co.uk/programmes/b006mk7h

I am interested to note that Mercury will be visible around sunrise from the middle of next week, looking south east. That means maybe 8 in the morning, so I shall be looking from my lab window when I get to school.

Jupiter was very bright in the sky over Wigton tonight, looking south west at about 6pm.

Renewable electricity??

I know what we mean by a renewable energy resource but I'm struggling with the idea that electricity is renewable. Assuming it keeps raining (a fair bet in the Scottish Highlands) then Lochan na Lairige will continue to be refilled with water. That's renewable. The water flows down the pipe below the dam from an altitude of 500 metres down to a power station on Loch Tay over 300 metres below. The gravitational potential energy turns into kinetic to drive a turbine and generate electricity. I teach that renewable means "won't run out". The gravitational potential in the water at the top of the hill will continue in perpetuity. So can we say that the electricity itself, as the end product, is renewable or should the sign say "electricity generated from a renewable energy source"??

St Albans

We had a great time ringing bells in St Albans but I didn't find much Physics. The bell tower at the Cathedral was very high up giving amazing views, so there is the Physics teacher's fall back of lightning conductors. If you magnify the image you'll see that they are copper due to the green colouration when corroded. I did like the notice in the second picture.

New College Oxford

New College Oxford is not new. In fact, it is one of the oldest colleges. It is now best known for this tree which appeared in one of the Harry Potter films. I was more taken by the giant sundial. The notice says that it was put in for the Millennium. It also explains why it does not show GMT and explains how to convert to GMT.

Absorption spectrum for the Sun

The boss found some old spectroscopes on Friday afternoon. The small ones turned out to be the best. I have never seen the absorption spectrum of the Sun with my own eyes before. Here it is! You can clearly see the black lines where hydrogen atoms in the colder (on 4000C ish!) chromosphere have absorbed photons of light and re-emitted them randomly, reducing the intensity. I'm ecstatic.