Star Pictures.

Progress, Volume II, Issue I, 1 November 1906, Page 17

Star Pictures.

At (lie annual meeting of the Philosophical Society the secretary (Mr f King) explained and exhibited certain stereographic star pictures drawn by Mr T. E. Heath, oi Cardiff, author of "A Roid-book to the Stars " Mr King explained how objects sufficiently near to the eye appeared solid through the combination of the images presented to the light and left eyes such images being seen from different points of view, and therefore, in slightly different perspective Scientific use of this fact had been made in the beautiful invention of the stereoscope about half a century ago, and that instrument, at first a scientific curiosity, had since done valuable service Its first astronomical application was to the moon, which for stereoscopic purposes had to be photographed at intervals of time, during the same phase, but in varying hbration ; the result being that the two pictures, united by the stereoscope, showed her as a spheroid. For the moon herself to be so seen at the distance of the earth, one would require a pair of eyes 66 000 miles apart At the Yerkes Observatory in the United States comets had been stereographically photographed, and, what was still more remarkable, meteor-tracks on two separate occasions. Some of these were shown, and the effect of the light gauzy mass,, standing out solidly against the background oi a black sky sprinkled with stars, was very striking and beautiful But no stereographic photographs of star-groups could be taken, the whole orbit of the earth being as a point compared with their vast distances Light travelled rather more than 185,000 miles a second, and took over eight minutes to reach us from the sun, but the nearest star was three " light-years " away, and there were stais visible to the eye whose light was two hundred years in reaching us, while the telescope revealed luminaries thousands of light-years away It was a curious fact that on a scale representing the solar distance as one inch a light year would equal a mile Mr Heath, with elaborate calculation and great pams, had drawn a great number of stereoscopic projections of stars of the greater magnitudes, and many of these were shown — one representing the familiar South Polar group, which never set in this region. The stereoscopic effect was very striking and beautiful the comparative degrees of distance being wonderfully brought out Mr. King explained that these views of the constellations were such

as would be given by a pair of eyes 107 lightyears apart In the discussion following, the chairman and other members described methods of combining stereographic pictures by the eyes alone, without the aid of an instrument.