Chapter 2

From horizon to opposite horizon, the sky takes up how much angular distance?

180 degrees

What is the period of nutation?

19 years

What is the precession period of the Earth's spin axis?

25,600 years

What is the maximum angular measure that a star at this latitude could possess in order to be considered a circumpolar star?

45 degrees

The sidereal period of Mercury is:

88 days

The Sun's apparent path around the celestial sphere is called

the ecliptic

Every celestial object appears to go around the Earth once a day. In addition to this motion, which celestial object has the fastest apparent motion in the sky?

the moon

Which of the following is NOT a result of the Earth's precession? a. the Earth wobbles b. where the Earth's axis points in the sky changes over the centuries and millenia c. Polaris will no longer be the North Star in several thousand years d. the stars twinkle when seen from the surface of planet Earth e. The signs of the zodiac most astrologers use are no longer in accord with the constellations in which the Sun is currently found over the course of the year

d. the stars twinkle when seen from the surface of planet Earth

When it comes to our place in the solar system today, which model do we accept?

heliocentric

Which of the following is NOT an argument for showing that the Earth must be round:

the Sun is seen blocking different constellations in the course of a year

If the Earth goes around the Sun, why is the ecliptic not lined up with the celestial equator?

the earth's axis is tilted by about 23 degrees from the vertical

In the Northern Hemisphere, the altitude (height in degrees above the horizon) of the North Star is always roughly equal to the

the tilt of the Earth's axis

What is the length of Jupiter's synodic period?

1.1 years

The star that is currently closest to the North Celestial Pole is:

polaris

The synodic period of Mercury is:

116 days

Which of the following was NOT done by Galileo Galilei? a. turning the telescope to the sky and believing what it showed his eyes b. discovering four large moons around Jupiter c. discovering that Venus goes through phases (like the Moon) d. resolving the Milky Way into many, many stars e. explaining retrograde motion with the heliocentric hypothesis

e. explaining retrograde motion with the heliocentric hypothesis

The slow tipping of the Earth's axis in a circle with a period of about 26,000 years is called:

precession

When a planet temporarily moves westward in the sky over the course of several weeks or months (instead of eastward, as it typically does), we call it:

retrograde motion

The celestial sphere turns once around each day because

the planet on which we live is rotating

The point in the sky directly above your head at any given time is called the

zenith

What is the length of Jupiter's sidereal period?

12 years

What is the rate of the Sun's diurnal motion across the sky?

15 degrees per hour

The great astronomer of ancient times who summarized and improved a system of circles upon circles to explain the complicated motions of the planets (and published the system in a book now called The Almagest) is: a. Hipparchus b. Copernicus Correct Response c. Ptolemy d. Pythagoras e. Alfonso the Wise Submit Your Answer

Ptolemy

Why do we observe diurnal motion from the surface of the Earth?

The Earth rotates on its spin axis carrying an observer in a complete rotation from west to east once every 12 hours

What causes the slow shift of the stars and constellations from one night to the next?

The Earth's revolution around the Sun once a year

As seen from the continental United States, the Big and Little Dipper

are in the north circumpolar zone throughout the year

According to the geocentric view, everything in the heavens had to go around the Earth, which was the center of the universe. What objects did Galileo discover with his telescope that clearly didn't go around the Earth?

moons around the planet Jupiter

The 88 sectors into which astronomers today divide the celestial sphere (the whole sky) are called:

constellations

Someone who observes the sky every clear night in Boston for many years will NEVER get to see:

the south circumpolar zone

The strip of the sky through which the Sun, the Moon, and the bright planets appear to move in the course of a year is called:

the zodiac

Which ancient Greek thinker suggested (long before Copernicus) that the Earth is moving around the Sun?

aristarchus

Is the following statement true or false? "Astrology has kept pace with our present knowledge of the changing sky".

false

The scientist who first devised experimental tests to demonstrate the validity of the heliocentric model of the solar system was

Galileo

Based on the scientific and statistical tests of astrological predictions, which of the following statements is the most reasonable?

astrology has not passed any clear scientific or statistical test and, as a result, most scientist are very doubtful that it can predict anything meaningful about our lives

A graduate student in geology who grew up in Florida (near the southernmost tip of the United States) gets to accompany her research professor to the North Pole. What will be different at the North Pole from the way she remembers the sky in Florida?

all of the above would be different from the way it is in florida

Within a constellation, a smaller, recognizable pattern of stars is often called

an asterism

The Sun, Moon, planets and stars rise in the ____ and set in the ____.

East, West

In what fundamental way did the work of Galileo differ from his predecessors who had thought about the sky?

Galileo used instruments and experiments to show him what nature was doing, instead of relying on pure logic

What problem has precession caused for many of the schools of astrology?

Because of precession, the constellations are no longer lines up with the astrological signs that are named after them; since astrology was set up, the two have slipped one sign apart

The Renaissance astronomer who wrote the pioneering book that suggested the Earth probably orbits the Sun (instead of the other way around) was:

Copernicus

In Copernicus' day, people were worried about the idea that the celestial sphere seemed to turn around us once a day because the Earth rotates. They argued that if the Earth were to rotate so fast, it should fly apart. According to our textbook, what was one response Copernicus had to this worry?

Copernicus argued that the idea that the much larger celestial sphere is turning once a day (and the Earth is not) meant that the celestial sphere would be torn apart even more

How does the heliocentric model explain retrograde motion?

It is a perspective effect as the faster Earth passes Mars in its orbit

The reason why Jupiter's direct motion is slower than that of Mars is because

Jupiter is further away from the Sun than Mars

From a city in the U.S., where in the sky would you look to see a star that is not turning with the motion of the sky in the course of a night?

at the north celestial pole

Let's say we find a star that is located on the points or circles in the sky listed in the answer choices below. Then, on the same night, we move to a location on Earth that is some significant distance from our first location. There will now be a different star at or on: a. the celestial north bole b. the zenith c. the celestial equator d. the celestial south pole e. all of the above

b. the zenith

How did Eratosthenes measure the size of the Earth?

by measuring the height of the Sun in the sky on the same day in two cities at different latitudes

On the celestial sphere, halfway between the celestial poles lies the

celestial equator

Which of the following was NOT done by Hipparchus, the great ancient astronomer? a. compiled a pioneering catalog of the positions of hundreds of stars b. created the system of star magnitudes that we still use today c. discovered that the Earth has a motion called precession d. explained retrograde motion

d. explained retrograde motion

Some Canadian troops are sent (as part of a U.N. peacekeeping force) to a country located on the Earth's equator. At night, when homesickness makes them gaze sleeplessly at the stars, which of the following will be familiar to them (the same at the equator as in Canada):

e. none of the above are the same on the equator as in canada

The south celestial pole and the north celestial pole lie in the sky directly above

the Earth's axis

Where on Earth do stars always circle the zenith (and never rise and set)?

the north pole

In Ptolemy's system the planets orbit the Earth and not the Sun. How did the system explain the retrograde motion of planets like Jupiter?

the planets moved on a small circle whose center, in turn, circled a point near the Earth