4The Four SeasonsIs the changing seasons caused by the change in the distance between the Sun and the Earth?No. If it is, thenThe northern and southern hemisphere should have the same season, not opposite season like we have.We should experience real seasonal changes in Hawaii also.…
5The Four Seasons: The Effect of the Tilt of Earth’s Rotation Axis
6Factors Affecting Earth’s Temperature Distance to heat sourceWeb Project: tutorial on , Chapter 2, Time and SeasonsIllumination AngleClick on the Sun to start animationNoon, Summer SolsticeSunrise/Sunset,Winter Solstice
7Solstices and Equinoxes Equinox: An equinox is one of two opposite points on the celestial sphere where the celestial equator and ecliptic intersect.Solstice: A solstice is either of the two times of the year when the sun is at its greatest distance from the equator.Spring Equinox ~ March 21Summer Solstice ~ June 21Fall Equinox ~ September 22Winter Solstice ~ December 21The dates of the equinoxes and solstices are only approximate dates.The actual length of a year is about 365 ¼ days (365 days, 5 hours, 49 minutes), not exactly 365 days. We have to add an extra day to a year every four years to keep the seasons synchronized with the seasons (leap year). Over a longer period of time, we need to skip a leap year to compensate the extra minutes we add in every leap year to keep the calendar in sync.Ecliptic PlaneSpring EquinoxWinter SolsticeCelestial EquatorFall EquinoxFall Solstice
8The Reasons for the Seasons on Earth The seasons on Earth are caused by the 23.5º tilt of its rotation axis, and its revolution around the Sun.Although the distance of the Earth to the Sun changes slightly as it orbits around the Sun, its effect is not big enough to cause the four seasons.The seasons for other planets may be due to the changing distance to the Sun, not the tilt of their rotation axis…For example, the orbit of Pluto has a very large eccentricity.