The Way the Sun Travels

Actually, the sun is fairly stationary. The rotation of the earth on its axis gives the illusion that the sun is moving.

There are only two days in the year when the sun rises in true east and sets in true west; in other words, when the sun follows exactly above the equator in its travel across the sky. These two days are equal in that day and night are equal length, thus the name equinox:

• Vernal equinox on or about March 21 1 st day of spring
• Autumnal equinox on or about September 23 1 st day of fall

Equinox: from the Latin aequus (equal) and nox (night).

The opposites of these two days are when, in winter, the day is the shortest and the night is the longest; and in the summer when the day is longest and the night is shortest, making the sun appear to stand still, thus the name solstice:

• Winter solstice on or about December 21 1 st day of winter
• Summer solstice on or about June 21 1 st day of summer

Solstice: from the Latin sol (sun) and sistere (to make stand still).

The apparent lines of travel of the sun on the solstices will be north of the equator in summer, and south of the equator in winter. These lines are called:

• Tropic of Cancer 23 degrees, 27 minutes North of the Equator
• Tropic of Capricorn 23 degrees, 27 minutes South of the Equator

Tropic: from the Greek tropikos (of a turn). Cancer: a northern constellation. Capricorn: a southern constellation.

If you follow the travel of the sun for one year, starting on March 21, it will swing north to the Tropic of Cancer, swing back south to the equator, continue south to the Tropic of Capricorn, then swing back north to the equator. The cycle repeats each year.

Keep in mind that the seasons are reversed in the southern hemisphere.

Because the earth is tilted on its axis, there is an area at the poles that will either be facing the sun all the time or away from the sun all the time during winter and summer. In the area facing the sun, there will be 24 hours of daylight (no night) during the summer; for the area facing away from the sun, there will be 24 hours of darkness (no day) during the winter. During fall and spring there will be a transition between these two extremes. The line marking this area in the north is the Arctic Circle; and the line marking this area in the south is the Antarctic Circle.

• Arctic Circle 23 degrees, 30 minutes from the North Pole
• Antarctic Circle 23 degrees, 30 minutes from the South Pole

The solstices and equinoxes mark the beginning of each season. There are also 4 other days that are important, and these 4 days mark the middle of each season. They are also known as quarter days. They are:

• February 2 Candlemas mid-winter
• April 30 Beltane (May Eve) mid-spring
• August 2 Lammas mid-summer
• October 31 Hallomas (Halloween) mid-fall

Questions:

• Since we are north of the equator, when is the sun directly overhead?
• How far south would you have to go before the sun could ever be directly overhead?
• How can we use the sun to tell true compass directions?
• Can we use the sun to help us determine the magnetic declination of an area? If so, how?
• How can you use shadows to tell the height of a tree?
• Can you think of another method to tell the height of a tree?
• Think of some ways to navigate without a compass.