Sunday 3 March 2013

High Above Us

The most direct route between two places around the surface of the earth is along a 'great circle'.  To imagine a great circle, mark two points on the skin of an orange, and then slice through the two points and the centre of the orange.  If this doesn't make sense, there's a mathematical explanation here.

Because it's the shortest distance, a far as possible aeroplanes follow a great circle line between two airports.  The consequence of this is that many flights from UK airports to North America don't go due westwards across the Atlantic but instead pass over Ardnamurchan - we know because, when flying between the UK and Canada, we've looked out of the window and seen the peninsula laid out below us.

As a result we see lots of contrails high above us.  It's frustrating looking up and wondering what plane it is, and where it's going.  So the Diary is very grateful to one of our neighbours, Tony Kidd, for drawing attention to flightradar24 which does for aeroplanes what the AIS sites do for passing ships.

On a related matter, those of us who enjoy watching the night skies are waiting in great anticipation for the arrival of comet PANSTARRS, which should be visible to us in the northern hemisphere in the next few weeks.  The Diary follows matters heavenly on the EarthSky website: sadly, it's having some technical difficulties today, but the link is here.




Skywatchers here on Ardnamurchan are having a frustrating time with their aurora watching.  This is the graph of geomagnetic activity for the last 24 hours, taken from the University of Lancaster's AuroraWatch site.  It's been much like this for the last two days, but a persistent cloud cover has made any sightings impossible.

Another site the Diary visits is NASA's 'Picture of the Day' - and some of those pictures are stunning.  As an example, there's a picture of planet Mercury here.

Lastly, many thanks to Jim Dempster for sending this link, which is to a video of one of the International Space Station's commanders giving a guided tour round this orbiting space laboratory, a wonderful feat of human engineering not least because it's been achieved by many nations working together, something that doesn't happen very often down here on Earth.

4 comments:

  1. This is a good auroral sighting prediction website, Jon http://helios.swpc.noaa.gov/ovation/

    ReplyDelete
  2. Many thanks for the link. Jon

    ReplyDelete
  3. If you see a con trail around noon on Thursday, please give it a wave. It could contain my daughter Anna and her partner, Matt on their way from Heathrow to San Francisco. Ardnamurchan is very dear to their hearts and they are looking forward to visiting it with us in June. But in the meantime, California will just have to do.

    ReplyDelete
  4. If you enjoy pictures from space, you should follow Canadian astronaut Chris Hadfield (@Cmdr_Hadfield on Twitter or Col. Chris Hadfield on Facebook) on the International Space Station.

    He has some spectacular photos, as you'd imaging from space! And if you go back to Wedneday 26th Feb, you'll see a picture of Skye and the Inner Hebrides, and just in view below is Ardnamurchan.

    ReplyDelete