Ast 115 Study guide Exam 1 Murray State

How far from Earth is the Moon?

1 lightsecond

Approximately, what is the age of the Universe?

14 billion years

How long does it take our solar system to complete one orbit around the Milky Way Galaxy?

230 million years

How many arcseconds are in one degree?

3,600

If the Moon is rising at midnight, the phase of the Moon must be

3rd quarter

How far from Earth is the nearest star besides the Sun?

4.2 lightyears

Approximately, what is the age of the Earth?

4.5 billion years

How many arcminutes are in one degree?

60

How many arcseconds are in one arcminute?

60

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

60Kg

How far from Earth is the Sun?

8.3 lightminutes

Galileo observed which of the following phases of Venus?

All

If traveling at the speed of light, approximately how far could you travel in one second?

Approximately seven times around the earth

What causes the apparent retrograde motion of the planets?

As Earth passes another planet, the other planet appears to move backward with respect to the background stars, but the planet's motion does not really change.

The controversial book of this famous person, published in 1543 (the year of his death), suggested that Earth and other planets orbit the Sun.

Copernicus

Suppose we imagine the Sun to be about the size of a grapefruit (about 10 cm across). Which of the following describes the size and distance of Earth on the same scale?

Earth is the size of a poppy seed about 10 meters away from the Sun.

Earth is always precisely 1 AU from the Sun. T or F

False

Kepler deduced his laws of planetary motion once Newton had published his universal law of gravitation. T or F

False

Our solar system is located very close to the center of the Milky Way Galaxy. T or F

False

The Ptolemaic model of the solar system was useless for predicting planetary positions. T or F

False

The solar system contains about 250 billion stars. T or F

False

There is no gravity in space. T or F

False

When energy is converted from one form to another, a tiny amount is inevitably lost. T or F

False

a lunar eclipse occurs only when the moon is new. T or F

False

He discovered that Jupiter has moons.

Galileo

How does the Space Shuttle take off?

Hot gas shoots out from the rocket and, by conservation of momentum, the shuttle moves in the opposite direction.

What makes the North Star, Polaris, special?

It appears very near the north celestial pole.

Which of the following statements does not use the term lightyear in an appropriate way?

It will take me lightyears to complete this homework assignment

He discovered that the orbits of planets are ellipses.

Kepler

The fact that Voyager 10 continues to speed out of the solar system, even though its rockets have no fuel, is an example of

Newton's first law of motion.

Has Polaris always been the "North Star"?

No, because the Earth's axis slowly changes the direction it points.

He developed a system for predicting planetary positions that remained in use for some 1,500 years.

Ptolemy

If traveling at the speed of light, approximately how far could you travel in one second?

Seven times around the earth

Which of the following is smallest? 1Au 1Light-second size of a star size of a planet

Size of a planet

In addition to the conditions required for any solar eclipse, what must also be true in order for you to observe a total solar eclipse?

The Moon's umbra must touch the area where you are located.

Why is it summer in the Northern Hemisphere when it is winter in the Southern Hemisphere?

The Northern Hemisphere is tilted toward the Sun and receives more direct sunlight.

The Earth is instantly replaced in its orbit by a speck of dust. Which statement best describes the subsequent orbital motion of that piece of dust?

The dust particle will continue in the same orbit as the Earth did, orbiting the Sun in 1 year

You are standing on a scale in an elevator. Suddenly you notice your weight decreases. What do you conclude?

The elevator is accelerating downwards.

What conditions are required for a lunar eclipse?

The phase of the Moon must be full, and the nodes of the Moon's orbit must be nearly aligned with Earth and the Sun.

What conditions are required for a solar eclipse?

The phase of the Moon must be new, and the nodes of the Moon's orbit must be nearly aligned with Earth and the Sun.

What happens during the apparent retrograde motion of a planet?

The planet appears to move eastward with respect to the stars over a period of many nights.

A solar eclipse occurs only when the Moon is new. T or F

True

One light year is about 10 trillion kilometers. T or F

True

One rotation of the galaxy takes about 200 million years. T or F

True

The Moon and the Sun are approximately the same angular size. T or F

True

The galaxy is about 100,000 lightyears in diameter. T or F

True

The solar system is a member of a galaxy containing approximately 250 billion stars. T or F

True

Kepler's second law, which states that as a planet moves around its orbit it sweeps out equal areas in equal times, means that

a planet travels faster when it is nearer to the Sun and slower when it is farther from the Sun

On a scale where the Sun is about the size of a grapefruit and the Earth is about 10 meters away, how far away are the nearest stars besides the Sun?

about the distance across the United States

How did Eratosthenes estimate the size of Earth in 240 B.C.?

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

Gasoline is useful in cars because it has

chemical potential energy.

in which direction does a quarter moon rise?

east

If the Moon is setting at 6 A.M., the phase of the Moon must be

full

When we see Venus in its full phase, what phase would Earth be in as seen by a hypothetical Venetian?

full

Which of the following is not a phase of the Moon?

half moon

The principle of Occam's Razor states that

in explaining natural phenomena, the simplest explanation consistent with the observations is to be preferred.

On a cosmic calendar, in which the history of the universe is compressed into 1 year, when did the dinosaurs become extinct?

in late December

The ultimate source of energy that powers the Sun is

mass energy of hydrogen fusing into helium.

The mass of Jupiter can be calculated by

measuring the orbital period and distance of one of Jupiter's moons.

At approximately what time would a full moon be on your meridian?

midnight

You are standing on Earth's equator. Which way is Polaris, the North star?

on the northern horizon

How many galaxies are there in the observable universe?

roughly (within a factor of 10) the same as the number of stars in our galaxy

Which of the following is largest? Size of pluto's orbit Size of a galaxy 1light-year distance to the nearest star

size of galaxy

An astronomical unit (AU) is ________.

the average distance between Earth and the Sun

Which of the following is the reason for the solar day being longer than a sidereal day?

the combined effect of the rotation of Earth and its orbit about the Sun

Orion is visible on winter evenings but not summer evenings because of

the location of earth in its orbit

If you see Polaris directly overhead at midnight, you must be at

the north pole

What is the ecliptic plane?

the plane of Earth's orbit around the Sun

The total number of stars in the observable universe is about ________.

the same as the number of grains of sand on all the beaches on Earth

0 degrees Kelvin is

the temperature at which all random particle motion stops.

The tides on Earth are an example of

the universal law of gravitation.

Why did Ptolemy have the planets orbiting Earth on "circles upon circles" in his model of the universe?

to explain the fact that planets sometimes appear to move westward, rather than eastward, relative to the stars in our sky