COSMIC RAY ENERGIES

Press, Volume XCIII, Issue 27911, 7 March 1956, Page 3

COSMIC RAY ENERGIES

BIG INCREASE RECORDED IN CHRISTCHURCH A spectacular increase in the intensity of cosmic radiation was recorded by scientists at the Geophysical Observatory in Christchurch last month. About 3.28 p.m. on February 23, radiation suddenly increased by 19 per cent, and normal radiation did not return until about 7 p.m. The increase marked one of the rare occasions when a stream of particles of cosmic ray energies escapes from the sun at the time of a solar flare and reaches the earth within an hour of the observation of the flare'of the sun. The last similar increase was recorded on November 19, 1949, and there have been only five such increases in the history of continuous cosmic ray recording, dating back to 1936. Four of these were recorded at Christchurch. The conditions required for particles of cosmic ray energies to escape from the sun and reach the earth are dependent on complex relationships between the sun’s magnetic field, transient magnetic fields of sunspots, and the earth’s magnetic field. Under normal conditions, matter from the sun would de deflected by the earth’s magnetic field and would reach the earths surface only near the magnetic poles. However, if the direction of emission is right and the configuration of the solar magnetic field and the earth’s magnetic field is also favourable, a tunnel is formed in the earth's magnetic field, through which particles of cosmic ray energies can pass. Because of the rotation of the earth the stream arriving sweeps across the surface of the earth like a searchI J pht or the path of an eclipse shadow. New Zealand seems to have been well off the centre line of the path during the February increase, otherwise the intensity change could have been much larger. The 1949 particle stream passed on a path between Australia and New Zealand, across the Pacific, through the United States and Canada. Northern Europe., China, and Antarctica.