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.