LONGEST DAY TOMORROW

Evening Star, Issue 22527, 21 December 1936, Page 8

LONGEST DAY TOMORROW

OCCURRENCE OF SOMMER SOLSTICE The longest day in the year, marking the period when the sun reaches its most southerly point, occurs to-morrow in this hemisphere. It is an event known as the summer solstice. The sun enters the sign Capricornus at noon. The earth is approaching perihelion (the nearest point to the sun), or a distance of 91,349,000 miles. In its journey of 580,000,000 miles round the sun the earth revolves at an average speed of nearly 19 miles a second, and even faster in December and January while the earth is approaching perihelion, and a trifle slower in June and July, when the earth is approaching and passing aphelion. Between perihelion and aphelion, there is a difference of over 3,000,000 miles. , This path is not circular, but is slightly oval in shape, with the sun not quite in the centre, but towards ona side. Unfortunately for the inhabitants of this hemisphere, this position of the sun has the effect of making summer slightly shorter and winter slightly longer than in the northern hemisphere. This is due to the angle at which the earth’s axis of rotation is tilted (being a little more than 23deg), and that angle results in the varying seasons. On a planet like Jupiter, with its axis of rotation almost vertical (4deg only) to the plane of its orbit, the succession of seasons, as experienced on this planet, must be practically nonexistent. '■ :