CSEC Geography Position of the Earth around the sun
Couva East Secondary Mrs. T. Persad-Smith
EFFECTS OF THE EARTH’S REVOLUTION AROUND THE SUN
Figure 1: Position of the Earth around the sun during the equinoxes and solstices. When the Sun shines down directly over a planet's equator -- that's an equinox. When one of the poles is tilted toward the Sun to its maximum extent -- that's a solstice. Four days during our calendar year — two solstices and two equinoxes — mark the beginnings of the four seasons. At the extremes are the winter and summer solstices, with the spring (vernal) and autumnal equinoxes occupying the midpoints. The solstices and equinoxes also mark four important points in Earth's orbit around the Sun. It's Earth's position in its orbit — and the orientation of its tilted axis at these points in its orbit — that defines the seasons. The solstices are six months apart and mark the days when the northern and southern hemispheres receive either maximum (summer) or minimum (winter) sunshine. In the north, the summer solstice, usually around June 21, is the longest day of the year; the winter solstice, six months later, is the shortest day of the year. Figure 1 shows the dates these events usually occur. The two equinoxes occur roughly midway between the solstices: the autumnal equinox in September and spring equinox in March. At these times, day and night are roughly of equal length. Contrary to the all-too-popular notion that Earth is closer to the Sun during summer and farther away during winter, seasons are not caused by the eccentricity of our planet's orbit. Indeed, during the hottest days of northern summer the Earth is at its greatest distance from the Sun. The primary cause of seasonal extremes on Earth is the 23½° tilt of our planet's spin axis. When the north pole is tilted toward the Sun, northern days are long and the weather is warm. Six months later, as the south pole tilts toward the Sun, the southern hemisphere takes its turn...