1|Page
As101 Exam Questions and Answers
100% Pass
In 1054 CE, the Chinese recorded a very interesting and powerful cosmic event. What
was this event?
a. star merger
b. a supernova
c. a galactic collapse
d. simultaneous solar and lunar eclipses - ✔✔b
What did Eratosthenes measure very accurateley?
a. the size of the Earth
b. the length of the year
c. the distance to the Moon
d. the length of the month - ✔✔a
Who were the two great authorities of Greek astronomy?
Author: Katelyn Whitman. ©2025, All Rights Reserved.
, 2|Page
b. Julius Caesar and Aristotle
a. Aristotle and Ptolemy
c. Columbus and Ptolemy
d. Alexander the Great and Julius Caesar - ✔✔a
Whose writings became so famous that he was known throughout the Middle East
simply as "The Philosopher"
a. Ptolemy
b. Eratosthenes
c. Aristotle
d. Hipparchus - ✔✔c
Which of the following statements reflects beliefs that were almost universally held in
pre Copernican astronomy?
a. The planets travelled in elliptical orbits around the Earth.
b. The planets travelled in elliptical orbits around the Sun.
c. The Sun was at the centre of the universe.
d. The Earth was at the centre of the universe. - ✔✔d
In what circumstances is retrograde motion observable?
Author: Katelyn Whitman. ©2025, All Rights Reserved.
, 3|Page
a. It is observable for planets located between the Earth and the Sun.
b. It is observable for planets more distant from the Sun than the Earth
c. It is only observable for the Moon.
d. It is observable for all planets. - ✔✔b
You are observing the night sky from Mars. In what circumstances is retrograde motion
observable?
a. It is observable for planets more distant from the Sun than Mars.
b. It is observable for planets located between Mars and the Sun.
c. It is only observable for Earth and Venus. d. It is observable for all planets. - ✔✔a
What is the term for the apparent westward motion of a planet in the sky compared to
the background stars (as viewed from the Earth) when observed on successive nights?
a. epicycle
b. retrograde motion
c. prograde motion
d. heliocentric motion - ✔✔b
What is parallax?
Author: Katelyn Whitman. ©2025, All Rights Reserved.
, 4|Page
a. the apparent motion of an object due to the motion of the observer
b. the distance between two straight lines.
c. the small circle that the planets slide along in Ptolemy's geocentric universe
d. the distance between two foci of an ellipse - ✔✔a
Q:10 Why did ancient astronomers believe that the Earth did not move?
a. because they could not detect parallax
b. because they believed in circular motion
c. because all observable planets follow retrograde motion
d. because parallax is only detectable during the day - ✔✔a
In Ptolemy's view of the universe, what is at the centre of a planet's epicycle?
a. the Sun
b. the Earth
c. the deferent
d. the equant - ✔✔c
Which of the following astronomers described the universe in a way that matches the
diagram?
a. Kepler
Author: Katelyn Whitman. ©2025, All Rights Reserved.
As101 Exam Questions and Answers
100% Pass
In 1054 CE, the Chinese recorded a very interesting and powerful cosmic event. What
was this event?
a. star merger
b. a supernova
c. a galactic collapse
d. simultaneous solar and lunar eclipses - ✔✔b
What did Eratosthenes measure very accurateley?
a. the size of the Earth
b. the length of the year
c. the distance to the Moon
d. the length of the month - ✔✔a
Who were the two great authorities of Greek astronomy?
Author: Katelyn Whitman. ©2025, All Rights Reserved.
, 2|Page
b. Julius Caesar and Aristotle
a. Aristotle and Ptolemy
c. Columbus and Ptolemy
d. Alexander the Great and Julius Caesar - ✔✔a
Whose writings became so famous that he was known throughout the Middle East
simply as "The Philosopher"
a. Ptolemy
b. Eratosthenes
c. Aristotle
d. Hipparchus - ✔✔c
Which of the following statements reflects beliefs that were almost universally held in
pre Copernican astronomy?
a. The planets travelled in elliptical orbits around the Earth.
b. The planets travelled in elliptical orbits around the Sun.
c. The Sun was at the centre of the universe.
d. The Earth was at the centre of the universe. - ✔✔d
In what circumstances is retrograde motion observable?
Author: Katelyn Whitman. ©2025, All Rights Reserved.
, 3|Page
a. It is observable for planets located between the Earth and the Sun.
b. It is observable for planets more distant from the Sun than the Earth
c. It is only observable for the Moon.
d. It is observable for all planets. - ✔✔b
You are observing the night sky from Mars. In what circumstances is retrograde motion
observable?
a. It is observable for planets more distant from the Sun than Mars.
b. It is observable for planets located between Mars and the Sun.
c. It is only observable for Earth and Venus. d. It is observable for all planets. - ✔✔a
What is the term for the apparent westward motion of a planet in the sky compared to
the background stars (as viewed from the Earth) when observed on successive nights?
a. epicycle
b. retrograde motion
c. prograde motion
d. heliocentric motion - ✔✔b
What is parallax?
Author: Katelyn Whitman. ©2025, All Rights Reserved.
, 4|Page
a. the apparent motion of an object due to the motion of the observer
b. the distance between two straight lines.
c. the small circle that the planets slide along in Ptolemy's geocentric universe
d. the distance between two foci of an ellipse - ✔✔a
Q:10 Why did ancient astronomers believe that the Earth did not move?
a. because they could not detect parallax
b. because they believed in circular motion
c. because all observable planets follow retrograde motion
d. because parallax is only detectable during the day - ✔✔a
In Ptolemy's view of the universe, what is at the centre of a planet's epicycle?
a. the Sun
b. the Earth
c. the deferent
d. the equant - ✔✔c
Which of the following astronomers described the universe in a way that matches the
diagram?
a. Kepler
Author: Katelyn Whitman. ©2025, All Rights Reserved.
