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50 Cards in this Set

  • Front
  • Back

About where is our solar system located within the Milky Way Galaxy?

about 2/3rds of the way from the center of the galaxy to the outskirts of the galactic disk

Which scientists played a major role in overturning the ancient idea of an Earth-centered universe, and about when?

Copernicus, Kepler, and Galileo; about 400 years ago

What is an astronomical unit?

the average distance from Earth to the Sun

What is the Sun mainly made of?

hydrogen and helium

The age of the universe is

between 10 billion and 16 billion years.

Modern telescopes are capable of seeing bright galaxies up to about

10 billion light years away.

Roughly how many star are in the Milky Way Galaxy?

100 billion

Which of the following best describes the modern definition of a constellation?

a region of the celestial sphere

What is the ecliptic?

the Sun's apparent path along the celestial sphere

Which of the following correctly describes the meridian of in your sky?

a half-circle extending from your horizon due north, through your zenith, to your horizon due south.

What is a circumpolar star?

a star that always remains above your horizon

We describe a position on Earth's surface by stating its

latitude and longitude

Why do we have seasons on the Earth?

As Earth goes around the Sun and Earth's axis remains pointed toward Polaris, the Northern and Southern hemispheres alternately receive more and less direct sunlight.

Why do we essentially see the same face of the Moon at all times?

because the Moon's rotational and orbital periods are equal

Why were ancient peoples unable to detect stellar parallax?

They did not have the ability to measure very small angles

Why do the structures of Stonehenge, the Templo Mayor, the Sun Dagger, and the Big Horn Medicine Wheel all have in common?

They were all used by ancient peoples for astronomical devices.

How did Eratosthenes estimate the size of Earth in 240 BC?

by comparing the maximum altitude of the Sun in two cities at different latitudes

Ptolemy was important in the history of astronomy because he

developed a model of the solar system that made sufficiently accurate predictions of planetary position to remain in use for many centuries.

The controversial book of this famous person, published in 1543, suggested that Earth and other planets orbit the Sun


He discovered that the orbits of planets are ellipses.


He discovered what we now call Newton's first law of motion


When Copernicus first created his Sun-centered model of the universe, it did not lead to substantially better predictions of planetary positions than the Ptolemaic model. Why not?

Copernicus used perfect circles for the orbits of the planets.

All of the following statements are true. Which one follows directly from Kepler's third law?

Venus orbits the Sun at a slower average speed than Mercury.

Which of the following is the reason for the leap years?

Earth year beginning on a non-integer number of Earth days.

All of the following are true. Which of the following gives evidence that Earth's orbit is not perfectly circular?

A) the Sun's angular size changes throughout the year AND B) Earth's seasons are not of exactly equal length

Which of the following is an example in which you are traveling at constant speed but not at constant velocity?

driving around in a circle at exactly 100 km/hr

Momentum is defined as

mass times velocity

If your mass is 60 kg on Earth, what would be your mass on the Moon?

60 kg

In which of the following cases would you feel weightless?

while falling from a roof

Suppose an object is moving in a straight line at 50 mi/hr. According to Newton's first law of motion, the object will

continue to move in the same way until is it acted upon by a force.

What quantities does angular momentum depend upon?

mass, velocity, and radius

Which of the following is not a conserved quantity?


Radiative energy is

energy carried by light

Considering Einstein's E=mc^2, which of the following statements is true?

A small amount of mass can be turned into a large amount of energy.

The force of gravity is an inverse square law. This means that if you double the distance between two large masses, the gravitational force between them

weakens by a factor of 4.

The allowed shapes for orbits under the force of gravity are

ellipses, parabolas, and hyperbolas.

According to what we now know from Newton's laws, which of the following best explains why Kepler's second law is true?

A planet's angular momentum must be conserved as it moves around its orbit.

Which of the following best describes the origin of ocean tides on Earth?

Tides are caused by the difference in the force of gravity exerted by the Moon across the sphere of the earth.

At which lunar phase(s) are tides most pronounced?

both new and full moons

According to the universal law of gravitation, the force due to gravity is

inversely proportional to the square of the distance between objects.

What is the meaning of the word cosmos?

the sum total of all matter and energy, that is, everything within and between all galaxies.

Which of the following has your "address" in the correct order?

you, Earth, solar system, Milky Way, Local Group, Local Supercluster

What do we mean when we say that the universe is expanding?

Average distances are increasing between galaxies.

How are galaxies important to our existence?

Galaxies recycle heavy elements produced in stars into future generations of stars.

How many stars can you see with your naked eye on a clear, moonless night from a dark location?

a few thousand

What makes the North Star, Polaris, special?

It appears very near the north celestial pole.

Which of the following statements about the Moon is true?

The Moon's distance from Earth varies during its orbit.

The names of the seven days of the week are based on the

seven naked-eye objects that appear to move among the constellations.

He discovered that Jupiter has moons.


Kepler's third law, p^2=a^3, means that

A) the period of a planet does not depend on its mass

B) planets that are farther from the Sun move at slower average speeds that nearer planets

C) all orbits with the same semimajor axis have the same period.

D)a planet's period does not depend on the eccentricity of its orbit.