Chapter-11 Keeping Time with the Skies — Online MCQ Test
SCIENCE · Grade 8 · CBSE(NCERT)
Practice Chapter-11 Keeping Time with the Skies with a free chapter-wise online MCQ test.
This chapter covers: celestial bodies - sundial - constellations - phases of the moon - rotation - revolution.
AI-generated questions from basic to board-exam level, with instant results and explanations.
Chapter-11 Keeping Time with the Skies — Important Questions & Answers
What is the term used to describe the apparent daily motion of the sun across the sky?
- A. Revolution
- B. Rotation
- C. Diurnal motion
- D. Orbital motion
Answer: C. Diurnal motion
Diurnal motion refers to the apparent daily motion of celestial bodies across the sky due to Earth's rotation. This is why the sun appears to move from east to west.
Diurnal motion refers to the apparent daily motion of celestial bodies across the sky due to Earth's rotation. This is why the sun appears to move from east to west.
Which celestial body orbits around the Earth?
- A. The Sun
- B. The Moon
- C. Venus
- D. Mars
Answer: B. The Moon
The Moon is Earth's natural satellite and orbits around Earth. The sun is at the center of our solar system, while Venus and Mars orbit the sun, not Earth.
The Moon is Earth's natural satellite and orbits around Earth. The sun is at the center of our solar system, while Venus and Mars orbit the sun, not Earth.
What is a constellation?
- A. A single bright star in the night sky
- B. A group of stars that form a recognizable pattern
- C. A planet visible to the naked eye
- D. A meteor shower event
Answer: B. A group of stars that form a recognizable pattern
A constellation is a group of stars that form a recognizable pattern when viewed from Earth. Examples include Orion, Ursa Major, and Cassiopeia.
A constellation is a group of stars that form a recognizable pattern when viewed from Earth. Examples include Orion, Ursa Major, and Cassiopeia.
How many phases does the Moon have in its complete cycle?
- A. 2
- B. 4
- C. 8
- D. 12
Answer: C. 8
The Moon has eight distinct phases in its complete cycle: new moon, waxing crescent, first quarter, waxing gibbous, full moon, waning gibbous, last quarter, and waning crescent.
The Moon has eight distinct phases in its complete cycle: new moon, waxing crescent, first quarter, waxing gibbous, full moon, waning gibbous, last quarter, and waning crescent.
What causes the sequence of day and night on Earth?
- A. Revolution of Earth around the Sun
- B. Rotation of Earth on its axis
- C. Orbital motion of the Moon
- D. Change in Earth's distance from the Sun
Answer: B. Rotation of Earth on its axis
The rotation of Earth on its axis causes different parts of Earth to face towards and away from the Sun alternately, producing the day-night cycle.
The rotation of Earth on its axis causes different parts of Earth to face towards and away from the Sun alternately, producing the day-night cycle.
If it is noon at your location, what time would it be at a place 180 degrees longitude away?
- A. Midnight (12:00 AM)
- B. 6:00 PM
- C. 6:00 AM
- D. 3:00 PM
Answer: A. Midnight (12:00 AM)
Earth rotates 360 degrees in 24 hours, so 180 degrees represents half of Earth, which is 12 hours difference. When it's noon on one side, it's midnight on the opposite side.
Earth rotates 360 degrees in 24 hours, so 180 degrees represents half of Earth, which is 12 hours difference. When it's noon on one side, it's midnight on the opposite side.
What is the relationship between the phases of the Moon and the relative positions of the Earth, Moon, and Sun?
- A. The phases depend only on Earth's rotation
- B. The phases are determined by the angle between the Moon's orbital plane and Earth's equator
- C. The phases result from the Moon's position in its orbit around Earth relative to the Sun's direction
- D. The phases are random and unpredictable
Answer: C. The phases result from the Moon's position in its orbit around Earth relative to the Sun's direction
As the Moon orbits Earth, its position relative to the Sun changes from our perspective. When the Moon is between Earth and Sun, we see a new moon; when it's on the opposite side, we see a full moon; other positions show intermediate phases.
As the Moon orbits Earth, its position relative to the Sun changes from our perspective. When the Moon is between Earth and Sun, we see a new moon; when it's on the opposite side, we see a full moon; other positions show intermediate phases.
How would ancient civilizations have determined the passage of seasons without modern calendars, and what role did celestial bodies play?
- A. They observed the changing positions of constellations and the sun's apparent height in the sky throughout the year
- B. They relied entirely on lunar phases
- C. They had no way to track seasons
- D. They used only the daily movement of stars
Answer: A. They observed the changing positions of constellations and the sun's apparent height in the sky throughout the year
Ancient civilizations tracked seasons by observing the changing positions of constellations (which appear at different times of year), the sun's height above the horizon, and the timing of sunrise and sunset throughout the year.
Ancient civilizations tracked seasons by observing the changing positions of constellations (which appear at different times of year), the sun's height above the horizon, and the timing of sunrise and sunset throughout the year.
If you could observe the sun's position in the sky every day at the same clock time, you would notice it traces a figure-eight pattern over a year. What is this phenomenon called, and what causes it?
- A. The analemma, caused by Earth's elliptical orbit and axial tilt combined effects
- B. A solar eclipse pattern
- C. Precession of Earth's axis
- D. The moon's orbital plane
Answer: A. The analemma, caused by Earth's elliptical orbit and axial tilt combined effects
The analemma is the figure-eight pattern traced by the sun when observed at the same clock time daily. It results from combining two effects: Earth's elliptical orbit (which varies the sun's apparent east-west position) and the axial tilt (which varies its north-south position).
The analemma is the figure-eight pattern traced by the sun when observed at the same clock time daily. It results from combining two effects: Earth's elliptical orbit (which varies the sun's apparent east-west position) and the axial tilt (which varies its north-south position).
During a lunar eclipse, the Moon appears reddish or copper-colored instead of completely black. Why does this phenomenon occur despite Earth's shadow completely covering the Moon?
- A. Sunlight is reflected from nearby planets
- B. Sunlight is refracted through Earth's atmosphere and bent onto the Moon's surface
- C. The Moon emits its own light during eclipses
- D. The eclipse is not actually complete
Answer: B. Sunlight is refracted through Earth's atmosphere and bent onto the Moon's surface
During a lunar eclipse, although the Moon is in Earth's umbra (complete shadow), some sunlight is refracted (bent) through Earth's atmosphere onto the Moon's surface. The shorter blue wavelengths scatter away while longer red wavelengths reach the Moon, creating the reddish appearance.
During a lunar eclipse, although the Moon is in Earth's umbra (complete shadow), some sunlight is refracted (bent) through Earth's atmosphere onto the Moon's surface. The shorter blue wavelengths scatter away while longer red wavelengths reach the Moon, creating the reddish appearance.