Description: Earth's axis is not perpendicular to Earth's orbit around the Sun, but inclined at an angle of 23.4 degrees. In consequence, the apparent position of the Sun in the sky at a particular time of day, varies over the year. Whenever the Sun is, on average, higher in the sky, more sunlight reaches a given area of ground. Over the year, this leads to warmer and cooler stretches of time, more pronounced for regions farther away from Earth's equator, which are called the seasons. Northern hemisphere seasons are opposite to southern seasons: Northern summer, the three months centered on June 21 when the northern hemisphere is tilted maximally towards the Sun, is southern winter, with the southern hemisphere tilted away, and vice versa for southern summer as the three-month period around December 21. Many parts of the Earth close to the equator have seasons that are different from the summer and winter pattern seen at temperate and arctic latitudes. It should be noted that the duration, beginning, and end of each season can be influenced by cultural practices and time period.

Related Terms:

• Equinox
• Equator
• Latitude
• Solstice
• Earth's Axis

Term and definition status: This term and its definition have been approved by a research astronomer and a teacher

The OAE Multilingual Glossary is a project of the IAU Office of Astronomy for Education (OAE) in collaboration with the IAU Office of Astronomy Outreach (OAO). The terms and definitions were chosen, written and reviewed by a collective effort from the OAE, the OAE Centers and Nodes, the OAE National Astronomy Education Coordinators (NAECs) and other volunteers. You can find a full list of credits here. All glossary terms and their definitions are released under a Creative Commons CC BY-4.0 license and should be credited to "IAU OAE".