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"Why does the hot planet Venus have polar caps like those of Mars if the Martian caps are really composed either of ice, snow or frozen carbon dioxide? Also, why do the polar caps of Venus and Mercury not wax and wane as those of Mars are said to do? And why are the polar caps of Mars seen to throw a mass of light many miles above the surface of the planet when they are seen in a side view if they are really of ice? How could they be so luminous in the first place - more luminous than snow is when seen under similar circumstances? And how could Lowell see direct gleams of light from the caps if there were not beams from a direct light source? "Furthermore, how do scientists account for the fact, noticed also by Professor Lowell, whose observations on Mars all seem to support our theory, that when the planet is viewed through a telescope at night, that its polar light is yellow and now white, as the light from snow caps would be? The central sun is an incandescent mass, and just as the glowing of an incandescent electric light looks yellow when seen from a distance through darkness, so the direct light of the Martian sun would appear yellow - but if this light were reflected from a solid white surface it would certainly appear white. But it does not, and so it is up to the scientists to tell us just why it does not. But so far as we know they have not succeeded in doing this." Mitchell saw two bright flashes of light at the polar cap of Mars which gradually came together. Gardner explains this as due to clouds which passed over the face of the interior sun, causing variations in the light emitted through the polar opening. An English astronomer, W E. Denning, writing in the scientific periodical, "Nature," concerning his observations in 1886, wrote: "During the past few months the north polar cap of Mars has been very bright, sometimes offering a startling contrast to those regions of the surface more feebly reflective. These luminous regions of Mars require at least as much careful investigation as the darker parts. In many previous drawings and descriptions of Mars, sufficient weight has not been accorded to these white spots." The English astronomer, J. Norman Lockyer, in 1892, wrote about Mars: "The snow zone was at times so bright that, like the crescent of the young moon, it appeared to project beyond the planet. This effect of irradiation was frequently visible. On one occasion the snow spot was S observed to shine like a nebulous a RS SO star when the planet itself was obscured by clouds, a phenomenon noticed by Beer and Madler, and recorded in their work, ‘Fragments Sur les Corps Celestes.' The brightness seemed to vary considerably, and at times, especially when the snow zone was near its minimum, it was by no means the prominent object it generally is upon the planet's disc."