Page 11 - Curriculum Visions Dynamic Book

heating of the Earth that causes re
The key to the seasons is the way the Earth
is tilted at 23.5°. This tilt causes one part of the Earth to face more directly into the sunlight.
In this part it is summer, while in the other part it is winter.
The effect is more pronounced at higher latitUdes and is less obvious in the tropics.
Although the Earth has clear seasons because its axis is tilted to the plane of its orbit, the Moon is almost upright (normal) in its orbit. As a result, it has no seasons. Sunlight is but glancing light at the poles on the Moon, and they are always almost dark and cold.
centrifUgal force A force that acts on an orbiting or spinning body, tending to oppose gravity and move away from the center of rotation.
eqUator The ring drawn around a body midway between the poles.
gravitational field The region surrounding a body in which that body’s gravitational force can be felt.
gravity The force of attraction between bodies. The larger an object, the more its gravitational pull on other objects.
latitUde Angular distance north or south of the equator, measured through 90°.
neap tide A tide showing the smallest difference between high and low tides.
seasons The characteristic cycle of events in the lated changes in
weather patterns.
spring tide A tide showing the greatest difference between high and low tides.
Northern spring
Northern winter
 This picture shows how the tilted Earth moves around the Sun.
Because the tilt is always in the same
direction, for one part of the year the northern hemisphere
faces toward the Sun more directly. That
produces summer. At the same time, the other
hemisphere has winter.
Northern autumn
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