Class 6 Geography Chapter 3 Question Answers - Motions of the Earth

Short Q & A : 

Q1: What is winter Solstice?
Ans: The position of the earth when it is winter season in the Northern Hemisphere and the summer season in the Southern Hemisphere is called Winter Solstice.

Q2: Distinguish between rotation and revolution.
Ans: 

Q3: Write short notes on Summer Solstice.
Ans: On 21st June, the Northern Hemisphere is tilted towards the sun. The rays of the sun fall directly on the Tropic of Cancer. As a result, this area receives more heat. Since a large portion of the Northern Hemisphere gets light from the sun, it is summer in the northern regions of the Equator. The longest day and the shortest night at these places occur. At this time in the Southern Hemisphere, all these conditions are reversed. It is winter there. The night is longer than the days. This position of the Earth is called the Summer Solstice.

Q4: What is a leap year how is it calculated?
Ans: When a year has 366 days instead of 365 days it is known as leap year. We say there are 365 days in the year and by this, we mean that it takes the earth 365 days to make its annual trip around the sun. Actually, though, It takes the Earth 365-1/4 days to make this trip. This means that every year we gain one-fourth of a day and every four years we gain one full day. If we did nothing about this, our calendar would move backwards one full day every four years to keep this from happening, we add the extra day every four years and put it into February.

Q5: How is the rotation of the Earth responsible for causing day and night?
Ans: The Earth rotates on its axis from West to East and completes it in 24 hours. When the Earth rotates, the half portion facing the sun causes day and the other half remains in darkness causing night. Thus, day and night is a continuous phenomenon because of the rotation.

Q6: What would happen if the Earth did not revolve?
Ans: If the Earth did not revolve, then:
i) There would be no change in seasons.
ii) There would not be a variety of flora and fauna on the earth.

Q7: Define the following terms: 
A. Dusk
B. Dawn
Ans : Dusk: - Is that period of the evening which has diffused light after sunset.
Dawn: - It is that period of the morning, which has diffused light just before sunrise.

Q8: Why the southern hemisphere celebrates Christmas in summer?
Ans: On 22nd December, the Tropic of Capricorn receives direct sun rays due to the tilt of the South Pole towards it. As the sun's rays are vertical on it, hence it has summers. Therefore, Christmas which falls on 25th December is celebrated in summer in the Southern Hemisphere.

Q9: Why is it hotter when the sun rays are vertical at a place?
Ans: The sun rays of the noon are hottest in comparison to the sun rays of the morning and evening. This is because the rays of the sun are almost vertical at noon. They fall over a small area and hence give a greater amount of heat which means the heat received per unit area increases. The rays of the sun are slanting in the morning and in the evening. They spread over a wider area and hence they cover a larger area but give less amount of heat. That is why it is hotter when the sun rays are vertical at a place.

Q10: Why our shadow seem to be long in the morning and evening but short in noon?
Ans: The shadows are long in the morning and evening and short at noon. It is the effect of slanting and direct rays of the sun. When the rays of the sun are overhead in the afternoon, the shadow is shortest. The rays of the sun are slanting during evening and morning hence the shadows are long.

Q11: When are the sun’s rays directly on the equator?
Ans: The sun’s rays fall directly on the equator during the equinoxes. There are two equinoxes each year:

1. March Equinox (around 21st March): This is the Vernal Equinox in the Northern Hemisphere. On this date, the sun's rays are directly overhead the equator, meaning that the entire earth experiences nearly equal lengths of day and night. This marks the beginning of spring in the Northern Hemisphere and autumn in the Southern Hemisphere.

2. September Equinox (around 23rd September): This is the Autumnal Equinox in the Northern Hemisphere. On this date, the sun’s rays are again directly overhead the equator, leading to nearly equal day and night lengths worldwide. This marks the beginning of autumn in the Northern Hemisphere and spring in the Southern Hemisphere.

During these equinoxes, the tilt of the Earth's axis is such that it is not tilted towards or away from the sun, resulting in the sun being positioned directly above the equator. This alignment causes the sun’s rays to strike the equator at a perpendicular angle, leading to equal day and night durations across the globe.

Q12: What do you understand by polar day and polar night?
Ans: The polar night occurs when the night lasts for more than 24 hours. This only occurs inside the polar circles. The opposite phenomenon, when the sun stays above the horizon for a long time is called the polar day or midnight sun.

Q13: What do you understand by the term autumn equinox?
Ans: On September 22nd or 23rd in the northern hemisphere, when night and day are nearly of the same length and the Sun crosses the equator moving southward. In the southern hemisphere on the 20th or 21st of March, the Sun crosses the equator moving northward it is known as the autumn equinox.

Q14: What is the relative importance of revolution of the earth?
Ans:  The revolution of the earth around the sun is crucial for the changing of seasons. As the earth moves in its orbit, different parts of the planet receive varying amounts of sunlight throughout the year. This variation in sunlight is responsible for the different seasons—summer, winter, spring, and autumn. Without this revolution, the distribution of sunlight would remain constant, and we would not experience seasonal changes.

Q15: Why do both hemispheres experience different winter and summer solstice?
Ans:  During May, June and July, the northern hemisphere is exposed to more direct sunlight because the hemisphere faces the sun. The same is true of the southern hemisphere in November, December and January. This is due to the tilt of the Earth. So June, July and August are the hottest months in the northern hemisphere and December, January and February are the hottest months in the southern hemisphere.

Long Q & A:   

Q1: Distinguish between summer solstice and winter solstice.
Ans: 

Q2: Why for about six months day and six months night experienced by poles ?
Ans: The poles experience about six months of day and six months of night due to the tilt of the Earth's axis. Here's how it works:

1. Earth’s Tilt and Rotation: The Earth's axis is tilted at an angle of about 23.5 degrees. This tilt causes different parts of the Earth to receive varying amounts of sunlight throughout the year.

2. Continuous Daylight: During summer in either hemisphere (Northern or Southern), the pole tilted towards the sun gets continuous daylight. For example, when the North Pole is tilted towards the sun, it experiences continuous daylight for about six months because the sun does not set below the horizon.

3. Continuous Darkness: Conversely, during winter, when the same pole is tilted away from the sun, it experiences continuous darkness. The sun stays below the horizon, causing the pole to have about six months of night.

4. Seasonal Changes: This pattern of continuous day and night repeats every six months because of the Earth’s rotation and its axial tilt. When it is summer in the Northern Hemisphere, the South Pole is experiencing winter, and vice versa.

This phenomenon occurs because the poles are positioned at the ends of the Earth’s rotational axis, leading to extreme variations in daylight and darkness.

Q3: Explain the equinox.
Ans: An equinox is a special time of the year when day and night are almost equal in length all around the world. Here’s a simple explanation:

1. What Happens During an Equinox?: On the equinox, the Sun’s rays shine directly on the equator. This means that the Sun is not tilted towards the North or South Pole. Because of this, both the Northern and Southern Hemispheres receive almost the same amount of sunlight.

2. Equal Day and Night: On the equinox, every place on Earth experiences almost 12 hours of daylight and 12 hours of night. This is because the Sun is positioned in such a way that its light is evenly spread across the globe.

3. When Does it Happen?: There are two equinoxes each year: one around March 21st (called the Spring or Vernal Equinox) and another around September 23rd (called the Autumnal Equinox). These dates mark the beginning of spring and autumn in the Northern Hemisphere and the beginning of autumn and spring in the Southern Hemisphere.

4. Why It’s Special: The equinox is special because it’s the only time of year when day and night are almost perfectly balanced everywhere on Earth.

So, during the equinox, everyone around the world gets to enjoy a nearly equal amount of daylight and darkness.

Q4: How are seasons caused?
Ans: Seasons are caused by the tilt of Earth's axis and its orbit around the Sun. Here’s how it works:

1. Earth's Tilt and Orbit: The Earth revolves around the Sun in an elliptical orbit. Its axis is tilted at an angle of 23.5° relative to its orbit. This tilt causes different parts of Earth to receive varying amounts of sunlight throughout the year.

2. Changing Seasons: As Earth moves around the Sun, the tilt causes different areas to receive more direct sunlight at different times of the year, creating seasons.

   • Spring Equinox (March 21): The Sun shines directly on the equator. Day and night are nearly equal in length. This marks the beginning of spring in the Northern Hemisphere and autumn in the Southern Hemisphere.

   • Summer Solstice (June 21): The Northern Hemisphere is tilted towards the Sun, and the Sun's rays hit the Tropic of Cancer (23.5° N) directly. This results in the longest day of the year and the start of summer in the Northern Hemisphere. The Southern Hemisphere experiences winter with shorter days and longer nights.

   • Autumn Equinox (September 23): The Sun shines directly on the equator again. Day and night are nearly equal. This marks the start of autumn in the Northern Hemisphere and spring in the Southern Hemisphere.

   • Winter Solstice (December 22): The Southern Hemisphere is tilted towards the Sun, and the Sun’s rays hit the Tropic of Capricorn (23.5° S) directly. This results in the longest day of the year in the Southern Hemisphere and the start of winter. The Northern Hemisphere experiences summer with longer days and shorter nights.

3. Impact: The changing position of the Earth relative to the Sun means that different parts of the Earth receive varying amounts of sunlight, leading to the four distinct seasons: Spring, Summer, Autumn, and Winter.