Question 1

Which of the following astronomers was a contemporary of (lived at the same time as)Galileo?

Accepted Answer

Kepler was a contemporary of Galileo. Newton was born after Galileo's death, Ptolemy and Copernicus lived centuries prior to Galileo.

Question 2

The semimajor axis of Earth's orbit is:

Accepted Answer

The semimajor axis is the average distance between Earth and the Sun, and it is defined as 1 astronomical unit (AU), which is approximately 149.6 million km. Therefore, option B is the correct answer. Options A, C, and D are incorrect because they do not correspond to the semimajor axis of Earth's orbit.

Question 3

The Crab Nebula is the result of a supernova explosion of a star that occurred at a distance of about 1.84 kpc from Earth.If people first saw the explosion in a.d.1054,when did the explosion actually occur?

Accepted Answer

To calculate, we can use the formula: distance (in kiloparsecs) = (age of supernova in years) / (constant value)

The constant value is usually taken as 3.1 for the Crab Nebula.

So, distance = 1.84 kpc = (age of supernova) / 3.1

Age of supernova = 1.84 x 3.1 kpc = 5.71 kpc

To convert kpc to years, we multiply by 3.086 x 10^13 years/kpc (the value of 1 kiloparsec in years).

Age of supernova = 5.71 kpc x 3.086 x 10^13 years/kpc = 1.76 x 10^14 years

Subtracting the year of observation (1054 AD) from the age gives the answer:

Age of explosion = 1.76 x 10^14 years - 1054 years = 1.76 x 10^14 years BCE or about 4946 BCE.

Therefore, the answer is D (about 4946 BC).

Question 4

One convenient statement of the distance traveled by light over very short times is that the speed of light is about "a foot per nanosecond." The speed of light is 3 × 10⁸ m/s.What,then,is a nanosecond?

Accepted Answer

A nanosecond is a unit of time equal to one billionth of a second (10-⁹), which is the closest option to a foot per nanosecond when using the speed of light in meters per second.

Question 5

If an astronomer finds an object at a distance of 6.8 AU from Earth,what is the object MOST likely to be?

Accepted Answer

The distance of 6.8 AU from Earth suggests that the object is within our own solar system. Most likely an object in our own solar system would be a comet, as they have highly elliptical orbits that can take them far from the Sun (up to distances of thousands of AU). Stars in our galaxy and distant galaxies would be much farther away, while an artificial satellite would not be at such a great distance from Earth.

Question 6

In which country did Galileo make his astronomical discoveries?

Accepted Answer

Galileo made his astronomical discoveries in Italy.

Question 7

An astronomer discovers an object at a distance of 28 Mpc from Earth.At this distance,what is the object MOST likely to be?

Accepted Answer

At a distance of 28 Mpc (mega parsecs), the object is too far to be a member of our solar system or even our galaxy. An artificial satellite would also not be visible at that distance, and thus the most likely explanation is that it is a distant galaxy.

Question 8

What fundamental belief about the universe,established by the Greeks and adopted by the early Christian church,was shattered by Galileo's observation of moons orbiting Jupiter?

Accepted Answer

Galileo's observation of moons orbiting Jupiter contradicted the geocentric model, which posited that everything in the universe orbits Earth. This model was widely accepted by the Greeks and the early Christian church.

Question 9

A certain star in our arm of the Milky Way is measured to be about 750 pc from Earth.Expressed in light-years,the distance is approximately:

Accepted Answer

1 parsec (pc) is approximately equal to 3.26 light-years (ly). Therefore, 750 pc is approximately 750 * 3.26 = 2445 ly.

Question 10

Place the following events in chronological order,from earliest to latest.

Accepted Answer

Copernicus's heliocentric model was proposed in the 16th century, followed by Galileo's discovery of Jupiter's moons in 1610, and then Kepler's third law was published in 1619. This puts the events in the order of A → B → C, making choice C the correct option.

Question 11

Galileo's observations suggested to him that the planets revolve around the Sun.This idea was:

Accepted Answer

Galileo's observations were consistent with the heliocentric model proposed by Copernicus, which stated that the planets revolve around the Sun. This model was in contrast to the geocentric model proposed by Ptolemy, which stated that the Earth was at the center of the universe. The Roman Catholic Church initially rejected the heliocentric model, but eventually accepted it as evidence for the Sun-centered solar system became overwhelming. Therefore, choice D is the best answer as it correctly identifies the source of Galileo's idea and its relationship to the work of other astronomers.

Question 12

Who was the first astronomer to use a telescope for viewing the sky?

Accepted Answer

Galileo was the first astronomer to use a telescope for viewing the sky in 1609. While Ptolemy, Brahe, and Newton made significant contributions to astronomy, none of them used a telescope.

Question 13

What is the distance between Earth and the nearest star?

Accepted Answer

The answer of What is the distance between Earth and...

Question 14

The distance to a certain star has been measured to be 750 ly.Expressed in parsecs,the distance is approximately:

Accepted Answer

1 parsec = 3.26 light years
Therefore, 750 light years = 750/3.26 parsecs = 230.06 parsecs (rounded to two decimal places). Thus, the closest option is B, 230 pc.

Question 15

The average distance from the Sun to Earth is 1.50 × 10¹¹ meters.The speed of light is 2.99 × 10⁸ m/s.So the Astronomical Unit could also be expressed as:

Accepted Answer

The speed of light is the distance light travels in one second (2.99 × 10⁸ m/s). Therefore, the time it takes for light to travel from the Sun to Earth is (1.50 × 10¹¹ meters) ÷ (2.99 × 10⁸ m/s) = 499 seconds, or about 8.3 minutes. This is the definition of an Astronomical Unit, so the answer is B, about 8.3 light minutes.

Question 16

Why did Galileo's observations of moons orbiting Jupiter disagree with the theory of the universe accepted up to that time in history?

Accepted Answer

Galileo's observations of moons orbiting Jupiter contradicted the geocentric model of the universe, which posited that all celestial bodies orbited Earth. The discovery of Jupiter's moons provided clear evidence that not everything in the cosmos revolved around Earth, challenging the prevailing astronomical paradigm of the time.

Question 17

If you were to look back from your spacecraft toward the solar system and you measured that the angle between Earth and the Sun was 1 second of arc,how far from the Sun would you be? (Assume that the Earth-Sun line is at right angles to your line of sight.)

Accepted Answer

A parallax angle of 1 arcsecond corresponds to a distance of 1 parsec (pc) from the Sun.

Question 18

An astronomer finds an object at a distance of 5.6 pc from Earth.At this distance,what is the object MOST likely to be?

Accepted Answer

At a distance of 5.6 pc, it is most likely to be a star in our Milky Way Galaxy. This distance is too far for any asteroid in our solar system or an artificial satellite orbiting Earth. Also, a distant galaxy would be much farther away, typically measured in millions of parsecs.

Question 19

A certain star is found to be 340 ly from Earth.Expressed in parsecs,the distance is approximately:

Accepted Answer

We can convert light years to parsecs using the formula: 1 pc = 3.26 ly. Thus, 340 ly = 340/3.26 pc ≈ 104.3 pc ≈ 105 pc. Therefore, the correct choice is B.

Question 20

The distance from Earth to the star Betelgeuse (in the constellation Orion)has been measured as 131 pc.Expressed in light-years,the distance is approximately:

Accepted Answer

1 parsec (pc) is approximately equal to 3.262 light-years (ly). Therefore, 131 pc is approximately 427 light-years (131 x 3.262 ≈ 427).

Quiz 2: Gravitation and the Waltz of the Planets

Which of the following astronomers was a contemporary of (lived at the same time as) Galileo?