Chapter 2 Vocabulary Flashcards
solar system
Earth, seven other major planets, and thousands of smaller bodies all revolve around the sun. Together with the sun, these bodies form our solar system.
orbit
Each planet follows its own path, or orbit, around the sun. The orbits vary from nearly circular to elliptical, or oval shaped.
revolution
Earth takes almost 365 1/4 days to make one revolution, or a complete circuit, around the sun. This period is what we define as one year.
leap year
Every four years, the extra fourths of a day are combined and added to the calendar as February 29th. A year that contains one of these extra days is called a leap year.
rotate
As earth orbits the sun, it rotates, or spins, on its axis.
axis
An axis is an imaginary line that passes through the center of earth from the North Pole to the South Pole.
atmosphere
The atmosphere is a layer of oxygen and gases that surrounds earth. As the earth rotates on its axis, the atmosphere moves with it.
summer solstice
On or about June 21, the North Pole is tilted toward teh sun. On noon of this day, the sun appears directly overhead at the Tropic of Cancer (23 1/2 degrees N latitude). In the northern hemisphere, this day is the summer solstice - the day with the most hours of sunlight. It is the beginning of summer, but only in the northern hemisphere. In the southern hemisphere, that same day is the day with the fewest hours of sunlight and marks the beginning of winter.
winter solstice
On or about December 22 the North Pole is tilted from the sun. At noon, the sun’s direct rays strike the Tropic of Capricorn. In the northern hemisphere, this day is the winter solstice - the day with the fewest hours of sunlight and the beginning of winter. This same day, however, marks the beginning of summer in the southern hemisphere.
equinox
Spring and autumn each begin on a day that falls midway between the two solstices. These two days are equinoxes, when day and night are of identical, or equal, length in both hemispheres. On or about March 21, the spring equinox occurs. On or about September 23, the fall equinox occurs. On both days, the noon sun shines directly over the equator.
tropics
Tropics are the low-latitude areas near the equator between the Tropic of Cancer and the Tropic of Capricorn. As a result, temperatures in the tropics tend to be very warm.
