Short Answer Questions: Movements of Earth

Q1: What would happen if the Earth suddenly stopped rotating?
Ans: If the Earth suddenly stopped rotating, everything on the surface would keep moving east at the same speed the Earth had been spinning. This would cause extremely strong winds and huge waves that could sweep across the land, widespread damage to buildings and roads, and major earthquakes as the ground adjusted. Many places would be destroyed, and life would be greatly disturbed. However, such a sudden stop is not possible because it would require an enormous amount of energy and is physically unrealistic.

Q2: How does the Earth's rotation affect the shape of the planet?
Ans: The Earth's rotation makes it slightly flattened at the poles and bulges at the equator. As the Earth spins, an outward force causes the middle of the planet to bulge a little. Because of this, the distance across the equator is a bit larger than the distance between the North and South Poles.

Q3: Explain why we have day and night on Earth.
Ans: Day and night happen because the Earth turns once every 24 hours. The side of the Earth that faces the Sun receives sunlight and has daytime, while the side turned away from the Sun is in darkness and has nighttime. As the Earth rotates, different places move into and out of sunlight, giving us the regular cycle of day and night.

Q4: How does the Earth's rotation influence the movement of water in the oceans?
Ans: The Earth's rotation makes moving water bend rather than flow in straight lines. This bending helps form large ocean currents and makes their paths curved. Tides are mainly caused by the Moon's gravity, but the Earth's rotation affects the timing and direction of water movement and so influences how ocean currents and tides behave.

Q5: Why do winds and ocean currents veer to the right in the Northern Hemisphere and to the left in the Southern Hemisphere?
Ans: This happens because of the Coriolis effect caused by the Earth's rotation. In the Northern Hemisphere, moving air and water are deflected to the right, and in the Southern Hemisphere, they are deflected to the left. This deflection makes winds and ocean currents curve and also affects the direction in which big storms spin (for example, many large cyclones spin anticlockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere).

Q6: How long does it take for the Earth to complete one orbit around the Sun, and what is this period called?
Ans: The Earth takes about 365.24 days to go once around the Sun. This period is called a year. Because of the extra 0.24 day, we add one extra day every four years, which is called a leap year.

Q7: What is perihelion, and when does it occur?
Ans: Perihelion is the point in the Earth's orbit when it is closest to the Sun. It happens around 3 January each year. Being slightly closer to the Sun at perihelion does not cause the seasons; seasons are caused by the tilt of the Earth's axis.

Q8: What is aphelion, and when does it occur?
Ans: Aphelion is the point in the Earth's orbit when it is farthest from the Sun. It occurs around 4 July each year. Like perihelion, aphelion has only a small effect on temperature; the main reason for seasons is the tilt of the Earth's axis.

Q9: How does the tilt of Earth's axis cause seasons?
Ans: The Earth's axis is tilted by about 23.5 degrees, and this tilt causes the seasons. When a hemisphere (North or South) is tilted towards the Sun, it receives more direct sunlight and longer days, so it has summer. When it is tilted away from the Sun, it gets less direct sunlight and shorter days, so it has winter.

Q10: Explain what happens during an equinox.
Ans: During an equinox, which happens twice a year (about 21 March and 23 September), the Sun is directly above the Earth's equator. As a result, day and night are nearly equal in length all over the world. These times mark the change between spring and summer, or between summer and autumn, depending on the hemisphere.