Introduction

Relevance of the Theme

We cannot ignore that Earth, our home, is a complex organism in perpetual motion. Understanding the movements of the Earth is essential, as they are the basis for the understanding of natural phenomena, such as the seasons, and also for various areas of science, including geography, physics, and astronomy.

Contextualization

Within the broader spectrum of geography and science, the study of Earth's movements fits into the subarea of physical geography, which focuses on the forces that shape the Earth's crust and the interaction between humans and the environment. This topic serves as a starting point for future discussions on the seasons, the distribution of insolation on the planet, time zones, and even the formation of earthquakes and volcanoes.

Theoretical Development

Components

• Rotation of the Earth around its own axis: The Earth performs a rotational movement, that is, it rotates around an imaginary axis called the axis of rotation. This movement is essential for the existence of day and night, and lasts approximately 24 hours, which determines our notion of time.

  • Consequences of Rotation: Earth's rotation is responsible for the alternation between day and night. During rotation, the half of the planet exposed to the Sun experiences daylight, while the other half, in shadow, experiences night.

• Earth's Revolution around the Sun: Revolution is the movement that Earth makes around the Sun. This movement is responsible for the occurrence of the seasons and for the difference in duration between day and night throughout the year. The revolution takes about 365 days and 6 hours, which results in the need for an additional day every four years (leap year).

  • Consequences of Revolution: Earth's revolution is responsible for the seasons, since depending on Earth's position in its orbit around the Sun, different portions of the planet receive different amounts of light and heat.

Key Terms

• Rotation: It is the movement that Earth makes when rotating around its own axis. Rotation is the cause of the succession between day and night.

• Revolution: It is the movement that Earth makes around the Sun. This movement is responsible for the creation of the seasons and for the variation in the duration of day and night throughout the year.

• Axis of Rotation: It is the imaginary axis around which Earth rotates during rotation.

• Seasons: There are four divisions of the year - spring, summer, autumn, and winter - determined by Earth's position in its orbit around the Sun and by the angle of inclination of its axis of rotation.

Examples and Cases

• Rotation and duration of day and night: The time it takes for any point on Earth to complete a rotation around its own axis defines the duration of day and night. If Earth did not rotate, any point would be constantly illuminated or in darkness.

• Revolution and seasons: During the revolution, the inclination of the axis of rotation causes different regions of the planet to receive varied amounts of solar radiation, resulting in the seasons. In the northern hemisphere, for example, when it is summer, it is winter in the southern hemisphere.

• Leap year and revolution: The need for February 29 in leap years arises due to the actual duration of the year being 365 days and 6 hours. These extra hours per year are compensated by adding a day every four years.

Detailed Summary

Relevant Points

• Rotation Movement: referring to the movement that Earth makes when rotating around its own axis, this is a fundamental characteristic of our planet that results in the succession of day and night. It is important to note that this movement also determines the apparent movement of the Sun in the sky.

• Revolution Movement: This is the movement that Earth makes around the Sun, which influences the seasons and the variation in the duration of day and night throughout the year.

• Consequences of Movements: It is essential to understand the consequences of these movements so that we can appreciate the nuances and richness of the natural world. Rotation, for example, is responsible for the rhythm of day and night, while revolution is responsible for the rhythm of the seasons, providing a constantly changing spectacle on our planet.

Conclusions

• Days and Nights: Earth's rotation is the force behind the 24-hour cycle that we experience as days and nights. Each complete rotation is a new day, with half of the planet bathed in sunlight, while the other half is in darkness.

• Seasons: Earth's revolution, combined with the inclination of its axis, results in the differences in the amounts of sunlight that reach different parts of the planet throughout the year, leading to the four distinct seasons.

• Leap Year: To compensate for the six-hour difference in the duration of Earth's revolution, every four years we add a day to the calendar, February 29, in what we call a leap year.

Exercises

1. Exercise 1: Explain what would happen if Earth stopped rotating. What would be the impact on the duration of day and night?

2. Exercise 2: Draw and explain the position of Earth in relation to the Sun during each of the seasons, taking into account the inclination of the revolution axis.

3. Exercise 3: Why do we need an extra day every four years? Describe what happens in the revolution movement that requires the addition of this day.