Chptr 2 Observing the Sky: The Birth of Astronomy

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

45 degrees

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

Aristarchus

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

latitude of the observer

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

the ecliptic

Which of the following is NOT a result of the Earth's precession?

the stars twinkle when seen from the surface of planet Earth

The ecliptic is inclined at 23.5 degrees to the celestial equator. This is the result of:

the tilt of Earth's rotational axis with respect to the orbital plane of the Earth

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:

the zenith

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

180 degrees

An observer notices that the Sun is directly overhead at midday during the Summer Solstice. What is this observer's latitude upon the Earth?

23.5 degrees North

Which statement regarding celestial objects seen at the poles is false?

All stars are visible over the course of a year from the poles

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

Galileo

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

How does the heliocentric model explain retrograde motion?

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

What happens to the position of Polaris in your sky as time advances over a period of a year?

It revolves in a very small circle around the north celestial pole

The relatively bright star near the north celestial pole is:

Polaris

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

Polaris

Which of the following relatively bright stars is the nearest to the south celestial pole (SCP), as shown in the Sky Chart? (Hint: Use the Search facility to locate these stars and zoom in towards the SCP. Then use the Measurement Tool to measure their angular distance from the SCP.)

Polaris Australis (Sigma Octantis)

From your observations of the position of Vega, what can you conclude about the rising of stars from night to night?

Stars rise 4 minutes earlier each night

Which of the following is NOT a feature of the Copernicus heliocentric model?

The Earth is assumed to remain stationary, to satisfy the common experience of Earth-bound observers

Which of the following constellations does the celestial equator not pass through?

Ursa Major

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

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

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

at the north pole

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

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

constellations

The celestial sphere turns once around each day because

the planet on which we live is rotating

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

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

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

zenith

Which of the following was NOT done by Hipparchus, the great ancient astronomer?

explained retrograde motion

Which of the following was NOT done by Galileo Galilei?

explaining retrograde motion with the heliocentric hypothesis

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

heliocentri

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 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

On what date does the Sun reach the most northerly point (the summer solstice) along the ecliptic? On what date does the Sun reach the most southerly point (the winter solstice) along the ecliptic?

June 21, December 21

On what date of the year does the Vernal Equinox occur? On what date of the year does the Autumnal Equinox occur? [Hint: Run time forward to find the two dates when the Sun is on the celestial equator.]

March 20, September 22

An observer in Earth's northern hemisphere is looking directly towards Polaris. In what direction is this observer facing?

North

Which of the following is NOT a constellation of the zodiac?

Orion

Which of the following celestial objects is NOT always found near the constellations of the zodiac?

Pluto

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:

Ptolemy

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

What is the relationship between the altitude of Polaris and the latitude of the observer?

The altitude of Polaris is almost the same as the latitude of the observer

Which of the following statements is correct?

The nighttime side of the Earth faces different parts of the sky during the year

Which of the following statements is NOT true?

The constellations show no motion over the course of one year

Polaris is part of which constellation?

Ursa Minor

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

an asterism

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

What is the orientation of the Big Dipper asterism in winter?

It sits with its handle downwards

Where would the celestial equator appear to be located for an observer standing directly on one of the Earth's poles? Hint: Change your location on the Earth to the North Pole under Location in the Settings view.

It would be parallel to and coincident with the horizon

How does the altitude of the north celestial pole relate to the observer's geographic latitude on the surface of the Earth?

The altitude of the NCP is equal to the observer's geographic latitude

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

are in the north circumpolar zone throughout the year

Virgo is considered to be a spring constellation in the northern hemisphere because:

it is highest in the southern sky at midnight in springtime

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):

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

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

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 an argument for showing that the Earth must be round:

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