CHALLENGE The Earth has a great diversity of landscapes. It is also the only celestial body in the Solar System where life exists. This is because of specific characteristics. Earth can maintain an average temperature of 15 ºC because it is at the right distance from the Sun , and it has gases that retain heat. This temperature is suitable for life. Earth is the largest of the rocky planets. Its size helps it to retain essential gases like oxygen, which is essential for respiration in many living things. The Earth has a relatively large satellite, the Moon , which is responsible for important phenomena such as the tides in the oceans. Our planet also has a lot of geological activity, which manifests itself in the form of earthquakes, volcanoes, raised relief, erosion , etc. Water on Earth can exist in three states: solid , liquid and gaseous. The balance between these states allows the water cycle to exist, which is an essential process for life. The Earth has a magnetic field that protects it from particles and the radiation from the Sun that can be ver y dangerous for living things. 1 E xplain the characteristics that make it possible for Earth to have such a variety of landscapes and for life to exist. 2 I n pairs, design a model to explain how the cycle of day and night occurs. Think about suitable materials to use. Use materials that you have at home or at school. 3 W hen it is hot in Spain, why is it cold in Argentina? Explain, using a diagram. 4 I magine that Earth's axis of rotation is perpendicular to the plane of its orbit. Do you think there would be seasons? What if it is parallel? Find out why. 18 1. Earth
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