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Glossary term: Seasons

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 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. 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.

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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".

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Related Media


A female astronaut explains in Arabic about the lack of seasons on Venus

Venus: A Planet Without Seasons

Caption: This infographic is part of the "Simplifying Astronomy for Arabic Speakers" project, which aims to provide simplified scientific information about Venus, one of the most mysterious planets in our solar system. Why Doesn’t Venus Have Seasons? Venus is an exception among the planets when it comes to seasonal changes. Unlike Earth and Mars, which have a noticeable axial tilt, Venus’ axis is nearly parallel to its orbital plane around the Sun. This means that both hemispheres receive the same amount of solar radiation throughout the year, leading to a lack of distinct seasons like those experienced on Earth. Extreme Temperatures Venus is known as the hottest planet in the solar system, with surface temperatures reaching 462°C (864°F) during the day and dropping to -173°C (-280°F) at night. This extreme variation does not occur due to axial tilt or rotation but is primarily caused by Venus’ thick atmosphere, which is composed mostly of carbon dioxide. This composition creates a runaway greenhouse effect, making Venus even hotter than Mercury, despite being farther from the Sun. The Impact of the Thick Atmosphere Venus' dense atmosphere plays a major role in stabilizing its temperatures, as it traps solar heat and prevents it from escaping into space. As a result, Venus remains consistently hot, whether in daylight or nighttime. Conclusion Venus presents a unique environment in the solar system, where its structure and extreme conditions prevent it from experiencing seasons like Earth. This makes it a fascinating target for scientists seeking to understand how atmospheric composition influences climate and temperature changes over time. Studying Venus is not just about exploring a single planet—it provides valuable insights into the evolution of planetary atmospheres and climate systems across the universe.
Credit: Ali Al-Edhari

License: CC-BY-4.0 Creative Commons Attribution 4.0 International (CC BY 4.0) icons

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