The Reasons for the Seasons

Gr. 9 Science Exploration Unit

• The planets revolve around the Sun in elliptical orbits.

• Each planet also rotates around its axis.

• Earth rotates, or makes a full turn (360 ), on its axis once every 24 hours.

• At any given time, half of Earth experiences daylight while the other half experiences darkness.

• Time zones are divisions of Earth’s regions, where each regions has the same time.

• The Earth revolves around the Sun in an orbit once each year.

• The tilt of the Earth’s axis affects the amount of daylight in an area.

• The seasons in the northern and southern hemispheres occur because the Earth remains tilted as it orbits the Sun.

• The tilt of the Earth causes different amounts of solar energy to reach the Earth’s surface.

• When it is winter in the northern hemisphere, it is summer in the southern hemisphere.

• Other planets with tilted axes also have seasons.

• Planets that do not have a tilted axis do not have seasons. Mercury, Venus and Jupiter fall into this category.

• A solstice is a day when the Earth’s axis is most inclined toward, or away from, the Sun.

• Equinoxes are days when the hours of daylight equal the hours of darkness.