F10.7 in Europe etc.
Ken Tapping, 16th December, 2015
Almost 70 years ago, NRC scientist Arthur Covington started a programme of measuring the level of solar activity. The data, known as the 10.7 solar radio flux, or simply F10.7, are used worldwide by those involved in activities that are directly or indirectly affected by the Sun. The measurements are now made at the NRC’s Dominion Radio Astrophysical Observatory, near Penticton, British Columbia. As our way of life becomes more dependent on transportation, energy and communications infrastructure, our vulnerability becomes ever higher.
A few days ago I returned from a European space weather meeting, sponsored by the European Space Agency and held in Ostend, Belgium. The term space weather is used to describe what happens in space and in our upper atmosphere in response to events on the Sun. I was there to talk about applications of F10.7 in our expanding activities on Earth, in the atmosphere and in space. The Sun affects many diverse areas of our lives, including power and communications outages, radiation hazards on polar air routes, space mission safety and even corrosion rates in oil and gas pipelines. The growing international importance of this Made in Canada data was very apparent at the meeting. It was “standing room only”, and the questions and discussion went on until the Chairman had to stop it so the other agenda items could be discussed. When we are concentrating on the day-to-day operation of the programme, it is easy to lose sight of the importance of the F10.7 data and its role in the world. Among other things this is a testament to Arthur Covington and his team.
At 11:48 EST, or 8:48pm PST on 21 December the Sun will reach the most southerly point in its yearly travels – the winter solstice. Around that time we have the minimum interval between sunrise and sunset, and the most hours of darkness. From that point the Sun will start moving northward again, rising a little earlier each day and setting a little later. Like the motion of a swing, the changes are tiny to start with, and then get bigger at an increasing rate. The number of hours of daylight is changing most rapidly around 21 March and 21 September, respectively the spring and autumn equinoxes. At those times the Sun is crossing the celestial equator and the hours of daylight and darkness are equal. One positive thing to say about two or three months centred on the winter solstice is long, dark nights for doing some skygazing. If you have binoculars there are at the very least three things you should have a look at.
In the southern sky there is a brilliant, blue-white star. It is too bright to miss, and is flashing all the colours of the rainbow. The star is Sirius. It is really just an ordinary, blue-white star, located just over eight light years away. The light show is due to our atmosphere and the star being low in the sky. However, it is still spectacular. Try viewing through binoculars. Then see what the show looks like when you put the binoculars a little out of focus. Now look upwards and to the right, to find the three stars in a row marking the belt of Orion the Hunter. Now scan down to where his sword would be. The binoculars will show a little silver cloud. That is the Orion Nebula, one of our nearest and most spectacular places where new stars are being born. Further up and to the right you will find the Pleiades, or Seven Sisters. To the unaided eye this star cluster looks like a necklace dropped by a careless goddess. Through binoculars it looks like a jewel box, hundreds of diamonds on black velvet. The silvery glow you might see in some places is a cosmic gas cloud lit up by the stars as they pass slowly through it. Now you’re all fired up, see what else you can discover!
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