A foundational look at Earth from an astronomical perspective. The syllabus focuses on its unique position in the circumstellar habitable zone, axial tilt, physical dimensions, internal density variations, and magnetospheric shield.
Which of the following statements is true regarding earth movement?
Earth rotates on its axis from west to east resulting into seasonal changes.
Earth revolution around sun results into occurrence of day and night on earth.
Correct Answer:
(C) Both 1 and 2 are false
Night and day occur on the earth due to the rotation of the earth on its axis from west to east, whereas due to the rotation of the earth around the sun, the seasons change on the earth.
Ques: 2
One Astronomical unit is average distance –
Correct Answer:
(A) Between Earth and Sun
An astronomical unit is the mean distance between the Earth and the Sun. 1 AU = 149.598 × 106 Km or 149.6 Million Km. In other various units its value is as follows.
In Meter – 1 AU = 149.598 × 109
In millimetre – 1 AU = 149.59 × 1012
Ques: 3
The earth is nearest to the sun on –
Correct Answer:
(A) 3rd January
The distance between the sun and the earth is minimum in the first week of January, this situation or position is called ‘Perihelion’. Generally, Perihelion occurs on 4th January. While opposite to it is on 4th July, the sun stands farthest from the earth and this position or situation is known as “Aphelion”.
Ques: 4
Who amongst the following was the first to state that the Earth was spherical?
Correct Answer:
(A) Aristotle
Aristotle (384-322 BC) was a Greek philosopher and scientist. In chapter -14, Volume-2 (Pages-297-98) of his book “On the Heavens” he described Earth as a spherical body. This book was translated into English by J. L. Stock. The Geographer and Philosopher Ptolemy belonged to the 1st century, Strabo to the 2nd century and Copernicus to the 15th-16th century. Thus, Aristotle was the first philosopher who argued that the Earth is spherical in shape.
Ques: 5
Given below are two statements, one is labelled as Assertion (A) and the other as Reason (R).
Assertion (A) : Moving from one place on earth to another place of high latitude, the weight of an object decreases.
Reason (R) : Earth is not a perfect sphere.
Choose the correct answer by using code given below –
(A) and (R) both are true, and (R) explains
(A) properly.
Correct Answer:
(D)
is false, but (R) is true.
The centrifugal force generated by the Earth’s axis rotation is maximum at equator. As the result of this force, the weight of any object is minimum at Equator and maximum at poles and also increases towards high latitude. Thus, statement (A) is false. The shape of Earth is nearest to an oblate spheroid. This shape is also known as Geoid and Earth is not perfectly spherical in shape. Thus, Reason (R) is true.
Ques: 6
A chemical element found in abundance in the Earth’s crust is–
Correct Answer:
(A) Oxygen
Oxygen is the chemical element found in abundance in the Earth’s crust. The percentage of various chemical elements in Earth’s crust is as follows –
(Element) (Percentage)
Oxygen (O) - 46.60
Silicon (Si) - 27.72
Aluminium (Al) - 8.13
Iron (Fe) - 5.00
Calcium (Ca) - 3.63
Sodium (Na) - 2.83
Potassium (K) - 2.59
Magnesium (Mg) - 2.09
Ques: 7
Time taken by light emitted from sun to reach earth is –
Correct Answer:
(C) 8 minutes
The radiation from the sun which is popularly known as sunlight is a mixture of electromagnetic waves. Sunlight takes an average of 8 minutes and 19 seconds to travel from the Sun to the Earth. These electromagnetic energy waves travel with a speed of 186,000 miles/second. Thus, the closest answer given in option (c) is true.