Question 1

Which of the following best describes the difference between astronomy and astrophysics?

Accepted Answer

Astronomy is the observation and cataloging of celestial objects, while astrophysics applies physical laws to understand their behavior.

Question 2

Galileo’s observations of the phases of Venus provided evidence for which astronomical model?

Accepted Answer

Heliocentric model, where the Sun is at the center of the solar system.

Question 3

If the mass of a planet doubles while its radius remains the same, how does its surface gravity change? Use the formula $$g = \frac{GM}{R^2$}.$$

Accepted Answer

It doubles.

Question 4

Which of the following best explains why we experience seasons on Earth?

Accepted Answer

Earth’s axis is tilted relative to its orbital plane, causing varying sunlight angles.

Question 5

A student observes the Moon moving eastward against the background stars over several nights. What is the primary cause of this motion?

Accepted Answer

The revolution of the Moon around Earth.

Question 6

Which of the following is NOT a direct result of the application of the scientific method in astronomy?

Accepted Answer

Belief in astrology as a predictive science.

Question 7

If a star is observed to have a parallax angle of $$0.1$$ arcseconds, what is its distance from Earth in parsecs? Use the formula $$d = \frac{1}{p}$$, where $$p is in $$arcseconds.

Accepted Answer

$$10$$ parsecs

Question 8

Which property of light allows astronomers to determine the chemical composition of stars?

Accepted Answer

Its spectrum, which shows absorption and emission lines.

Question 9

A planet orbits the Sun at a distance of $$4 AU. $$According to Kepler’s third law, what is its orbital period in years? Use $$P^2$$ = $$a^3.$$

Accepted Answer

$$8$$ years

Question 10

Which of the following best describes the cosmic microwave background (CMB)?

Accepted Answer

Remnant heat from the Big Bang, observed as uniform microwave radiation.

Question 11

Which of the following statements about black holes is correct?

Accepted Answer

Black holes have a gravitational pull so strong that not even light can escape.

Question 12

If the Sun were suddenly replaced by a star with twice its mass, what would happen to Earth's orbital period? Use $$P^2$$ = \frac{$$a^3$$}{M}$$, where M$ is the mass of the Sun in solar masses.

Accepted Answer

Earth’s orbital period would decrease.

Question 13

Which of the following is a reason why astronomers use telescopes located in space rather than on Earth?

Accepted Answer

Space telescopes avoid atmospheric distortion and absorption.

Question 14

Which of the following best explains why the phases of the Moon occur?

Accepted Answer

The relative positions of the Earth, Moon, and Sun cause varying amounts of the Moon’s illuminated half to be visible from Earth.

Question 15

A star’s spectrum shows strong hydrogen absorption lines. What does this indicate about the star?

Accepted Answer

The star’s atmosphere contains a significant amount of hydrogen.

Question 16

Which of the following is a consequence of the tilt of Earth’s axis?

Accepted Answer

Different hemispheres experience opposite seasons at the same time.

Question 17

If a galaxy is observed to be moving away from us, what does its spectrum show?

Accepted Answer

A redshift in its spectral lines.

Question 18

Which of the following is a key reason why the scientific method is important in astronomy?

Accepted Answer

It allows astronomers to make predictions that can be tested and refined.

Question 19

A student measures the brightness of two stars. Star A is twice as far away as Star B but appears equally bright. What can be concluded about their luminosities? Use $$F = \frac{L}{4\pi d^2$}.$$

Accepted Answer

Star A has four times the luminosity of Star B.

Question 20

Which of the following is a breakthrough brought by technology to astronomy?

Accepted Answer

The invention of the telescope, allowing observation of distant objects.

NW 264: Explorations into Astrophysics – Syllabus and Study Guide

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