Earth's Rotation Causes Day and Night

The correct answer to the question "What causes day and night on Earth?" is option 'b', which states that the Earth's rotation is responsible for the occurrence of day and night. Let's explore this answer in detail.

Earth's Rotation
- The Earth is constantly spinning or rotating on its axis, an imaginary line running through its center from the North Pole to the South Pole.
- This rotation takes approximately 24 hours to complete, resulting in one full day.
- As the Earth rotates, different parts of its surface are exposed to the Sun's light, creating the phenomenon of day and night.

Daytime
- When a specific region on Earth is facing towards the Sun due to the rotation, it is daytime in that region.
- During the daytime, the Sun's rays directly illuminate the Earth's surface, providing light and warmth.
- This illumination allows us to see our surroundings clearly and engage in various activities.

Nighttime
- Conversely, when a particular region on Earth is facing away from the Sun due to the rotation, it is nighttime in that region.
- During the nighttime, the Sun's light does not reach the Earth's surface directly in that specific area.
- As a result, the region becomes darker, and the absence of sunlight brings about darkness.

Duration of Day and Night
- The duration of day and night varies based on the Earth's rotation and its position in relation to the Sun.
- During the summer months, the northern hemisphere tilts towards the Sun, resulting in longer daylight hours.
- In contrast, during the winter months, the northern hemisphere tilts away from the Sun, leading to shorter daylight hours.
- The opposite occurs in the southern hemisphere due to its position in relation to the Sun.

Conclusion
In summary, the Earth's rotation is the primary factor responsible for the occurrence of day and night. As the Earth spins on its axis, different parts of its surface experience either daytime or nighttime, depending on their position in relation to the Sun. This rotation causes the cycle of day and night, providing us with alternating periods of light and darkness.