(i) Which of the following is Earth's natural satellite?
(a) Mars
(b) Venus
(c) Moon
(d) Sun
Ans: (c)
The Moon is Earth's only natural satellite. It orbits around the Earth and is held in place by gravity.
(ii) What causes the tides on Earth?
(a) The Sun's gravity
(b) The Moon's gravity
(c) Earth's magnetic field
(d) The rotation of the Earth
Ans: (b)
The Moon's gravity pulls on Earth's oceans, causing tides. The Sun's gravity also has a smaller effect, but the main cause of tides is the Moon's gravitational pull.
(iii) How long does it take for the Earth to complete one rotation on its axis?
(a) 24 hours
(b) 12 hours
(c) 48 hours
(d) 36 hours
Ans: (a)
It takes approximately 24 hours for Earth to complete one rotation on its axis. This rotation is what causes day and night.
(iv) What is the shape of Earth?
(a) Perfect sphere
(b) Oblate spheroid
(c) Cube
(d) Flat
Ans: (b)
Earth is not a perfect sphere, but rather an oblate spheroid. This means it is slightly flattened at the poles and bulging at the equator due to its rotation.
(v) Which of the following is NOT a phase of the Moon?
(a) Full Moon
(b) New Moon
(c) Half Moon
(d) Red Moon
Ans: (d)
A Red Moon is not a recognized phase of the Moon. The Moon's phases include New Moon, Waxing Crescent, First Quarter, Waxing Gibbous, Full Moon, Waning Gibbous, Last Quarter, and Waning Crescent.
(i) The Earth has _______ natural satellite(s).
Ans: The Earth has 1 natural satellite(s).
(ii) The Earth's natural satellite is called the _______.
Ans: The Earth's natural satellite is called the Moon.
(iii) A _______ is a celestial body that orbits around a planet.
Ans: A satellite is a celestial body that orbits around a planet.
(iv) The _______ of the Moon is about 1/6th that of Earth.
Ans: The gravity of the Moon is about 1/6th that of Earth.
(v) Earth's atmosphere is made up of _______% Nitrogen, _______% Oxygen, and trace amounts of other gases.
Ans: Earth's atmosphere is made up of 78 % Nitrogen, 21 % Oxygen, and trace amounts of other gases.
Ans: (i) : (b) 12,742 km: The diameter of Earth is approximately 12,742 km.
(ii) : (c) 3,474 km: The diameter of the Moon is approximately 3,474 km.
(iii) : (a) 384,400 km: The average distance between Earth and the Moon is approximately 384,400 km.
(iv) : (e) 24 hours: Earth's rotation period, or the time it takes for Earth to complete one rotation on its axis, is approximately 24 hours.
(v) : (d) 27.3 days: The Moon's rotation period, or the time it takes for the Moon to complete one rotation on its axis, is approximately 27.3 days.
(i) The Moon is the fifth largest natural satellite in the solar system.
Ans: False
The Moon is the fifth largest natural satellite in the solar system.
(ii) The Moon's gravity is stronger than Earth's gravity.
Ans: False
The Moon's gravity is weaker than Earth's gravity, at about 1/6th the strength of Earth's gravity.
(iii) One side of the Moon always faces the Earth.
Ans: True
One side of the Moon always faces the Earth due to a phenomenon called tidal locking, which means that the same side of the Moon is always visible from Earth.
(iv) Earth has two natural satellites.
Ans: False
Earth has only one natural satellite, which is the Moon.
(v) The Moon affects the Earth's tides.
Ans: True
The Moon affects the Earth's tides by exerting a gravitational force on the Earth, causing the water in the oceans to rise and fall in a regular cycle.
(ii) Explain the term 'geocentric model.'
Ans: The geocentric model is an outdated astronomical model where Earth is considered the center of the universe, and all celestial bodies, including the Sun and Moon, revolve around it. This model was replaced by the heliocentric model, which places the Sun at the center of the solar system.
(iii) How does the Moon affect the Earth's climate?
Ans: The Moon affects Earth's climate mainly by causing tides. Tides influence ocean currents, which in turn play a role in the distribution of heat across the Earth's surface. This can impact weather patterns and climate.
(iv) What causes the Moon to appear differently in the sky during different phases?
Ans: The Moon appears differently in the sky during different phases because of the changing angle of sunlight hitting its surface as it orbits Earth. This causes the visible portion of the Moon to change, creating the different phases we observe from Earth.
(v) Why do we always see the same side of the Moon from Earth?
Ans: We always see the same side of the Moon from Earth because the Moon's rotation period is the same as its orbital period around Earth. This phenomenon is called tidal locking and is a result of the gravitational interaction between the Earth and the Moon.
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1. What is a natural satellite? |
2. How many natural satellites does Earth have? |
3. What is the significance of Earth's natural satellite? |
4. Can other planets have more than one natural satellite? |
5. How does the Moon affect human life on Earth? |
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