Astronomy Final

You've just found out that, in going once around its orbit, the Moon travels 2,410,000 km in (2.4x10^6) s (2,360,000 seconds). What is the speed of the Moon in km/s?

(1.0x10^0) To do the full problem from start to finish you could write (2*3.14*3.84x10^5) km / (27.3x24x60x60) s= 1.02 km/s Interesting that the speed is almost exactly 1 km/s. You should find that the speed of the Earth in its orbit about the Sun is faster.

How many degrees is 3600" (that is, 3600 arc-seconds)?

(1)

Willa is on the asteroid Xu. (Asteroids are small planets.) She starts from one pole of Xu and walks without turning until she reaches a place where the stars appear to move in horizontal circles, never rising or setting. If she has walked 80 km, what is the circumference of Xu in km?

(160) The stars appear to move in horizontal circles when you stand at one of the poles. Willa started at one pole and walked to the other pole, halfway around Xu.

The planet Earth has 4 times the radius of Krypton, but has the same mass. If you weigh 288 pounds on Krypton, how many pounds would you weigh on the Earth?

(18) Your weight is the gravitational force on you from the planet. The gravitational force on you is proportional to 1/R2, with R the distance to the center of the planet. If you are on a planet with 3 times the radius of Krypton, you would weigh only 1/32 as much. If, for example, you weigh 360 lb on Krypton, your weight on Earth would be 360 lb/32 = 40 lb. (The radius of Krypton changes each time you do the problem.)

Translate the number 3x10^7 to ordinary notation.

30,000,000

Find ((4.0x10^9))/((1.000x10^4)), expressing the answer in scientific notation.

4x10^5

What causes the Moon's phases?

As the Moon orbits the Earth, the part of the Moon that is lit is a changing fraction of the part that faces the Earth.

Copernicus lived at the same time as

Columbus

From the following names, who first measured the Earth's circumference to an accurancy of about 1%?

Eratosthenes

Who measured the Earth's circumference by comparing the height of the Sun in Alexandria to its height in Syene?

Eratosthenes, eratosthenes

Both attracting and repelling gravitational forces exist.

False

The Copernican revolution began with the invention of the telescope.

False

The reason for the seasons is the varying distance between the sun and earth.

False

From the following names, who first discovered the moons of Jupiter?

Galileo

Who discovered the precession of the equinoxes?

Hipparchus, hipparchus, Hipparchos, hipparchos

Describe the daily motion of Polaris:

It stays nearly fixed in the northern sky above our North Pole.

If the Moon's orbit were exactly in the plane of the Earth's orbit about the Sun, one would expect an eclipse of the Moon to occur about once every

month

The Moon revolves around the Earth about once every

month

What is the phase of the moon on the night of a solar eclipse?

new

Which of the following objects has an apparent motion with retrograde loops?

none of these the Sun the Moon Polaris

At full moon, as seen from the Earth, the Moon lies

opposite the Sun

Each Zodiac constellation contains part of the

plane of the Earth's orbit

What is parallax?

The apparent shift in the direction to object when the object is viewed from two different locations.

The absorption lines of helium have the same wavelength as its emission lines.

True

On a night when the Moon rises at midnight, what is its phase?

half-moon (3rd quarter)

Write 32,000 in powers-of-ten notation.

3.2x104

What shape is the orbit of a comet that passes through the solar system once and never returns?

hyperbola

A planet in the solar system whose period is 1 year is what distance from the Sun?

1 AU

__6__ red __3__ ultraviolet __8__ radio __1__ gamma-ray __7__ infrared __5__ green __4__ blue __2__ x-ray

1) Gamma-Ray 2)X-ray 3)Ultraviolet 4)Blue 5)Green 6)Red 7)Infrared 8)Radio

Order the following objects from closest to farthest from the Sun.

1) Venus 2) Saturn 3) Proxima Centauri 4) The Andromeda Galaxy 5) The Virgo Cluster

Willa is on the asteroid Xu. (Asteroids are small planets.) She starts from one pole of Xu and walks without turning until she reaches a place where the stars appear to move in horizontal circles, never rising or setting. If she has walked 90 km, what is the circumference of Xu in km?

(180) The stars appear to move in horizontal circles when you stand at one of the poles. Willa started at one pole and walked to the other pole, halfway around Xu.

Match the following names to the discoveries listed below: 1. Eratosthenes 2. Newton 3. Copernicus 4. Galileo 5. Ptolemy

(2) First found that gravity could account for the motion of the planets. (5) His model of the universe used epicycles to explain retrograde motion. (1) First measured the Earth's circumference to an accuracy of about 1%. (4) First discovered moons of Jupiter.

Match the real motions listed below to their periods.

(2) day (4) 1 month (1) 26,000 years (3) 1 year 1. Precession of the Earth's axis of rotation 2. Rotation of the Earth about its axis 3. One orbit of the Earth about the Sun 4. One orbit of the Moon about the Earth

It takes (2.7x10^1) days (27.3 days) for the Moon to orbit the Earth, relative to the stars (returning to its same position on the celestial sphere). How many seconds is that? Give the answer to two significant figures.

(2.3x10^6)

This is the first part of a 3-part problem asking you to find the speed of the Moon in its orbit. The distance to the Moon is (3.8x10^5) km. What is the circumference (in km) of the Moon's orbit? Assume the orbit is a circle, and give the answer to two significant figures (one digit to the left and one digit to the right of the decimal point).

(2.4x10^6)

An upscale Martian lander rolls north from the equator of Mars to a point whose latitude is 45 degrees north. If the lander has traveled 2,500 km, what is the circumference of Mars? Give the answer in km.

(20000.0)

The planet Earth has 5 times the mass of the planet Remus, but has the same radius. If you weigh 50 pounds on Remus, how many pounds would you weigh on the Earth?

(250)

An asteroid is in circular orbit 9 AU from the Sun. What is the period of the asteroid in years?

(27)

How many degrees is 180'? (1' means 1 minute of arc).

(3)

Find the speed of the Earth in its orbit about the Sun, using the distance (1.5x10^8) km from Sun to Earth. Give the answer in km/s to two significant figures.

(3.0x10^1)

An small icy planet (plutoid) is in circular orbit (5.0x10^1) AU from the Sun. What is the period of the planet's orbit in years?

(3.5x10^2)

Leto is on the planet Arrakis. He starts from one pole of Arrakis and travels without turning until he reaches a place where the stars appear to rise and set vertically. If he has walked 8000 km, what is the circumference of Xu in km?

(32000) The stars rise and set vertically as see from the equator. Leto started at one pole and walked to equator, one quarter of the way around Arrakis.

Match the apparent motions listed on the right to the real motions that cause them.

(4) The Moon's orbit about the Earth. (3) The change in the direction of the Earth's axis of rotation. (2) The Earth's orbit about the Sun. (1) The rotation of the Earth about its axis. 1. The daily rising and setting of the Sun. 2. The motion of the Sun through the constellations of the Zodiac. 3. The precession of the equinoxes. 4. The motion of the Moon through the constellations of the Zodiac.

Leto is on the planet Arrakis. He starts from one pole of Arrakis and travels without turning until he reaches a place where the stars appear to rise and set vertically. If he has walked 11000 km, what is the circumference of Xu in km?

(44000)

Match the following names to the achievements described in the next two questions 1. Brahe 2. Aristotle 3. Ptolemy 4. Einstein 5. Hipparchos

(5) Who discovered the precession of the equinoxes? (1) Whose accurate measurements of planetary positions led the way to Kepler's laws?

Match the following times of the year to the Sun's latitude north or south of the equator.

(5) between 23.5o and 90o S of the equator (4) between 0 and 23.5o N of the equator (3) 23.5o S of the equator (1) directly over the equator (5) directly over the S pole (2) 23.5o N of the equator 1. sping (vernal) equinox 2. summer solstice 3. winter solstice 4. May 1 5. never

How many minutes of arc is 10o?

(600)

How long, in seconds, does it take a radar signal to make a round-trip between Earth and Mars when the two planets are 0.6 AU apart? Give the answer in ordinary notation (e.g. 35000) not in scientific notation (3.5x104). You can use as the speed of light 3x105km/s.

(600) Here's how to do it for a distance of 2 AU from Earth to Mars (the distance of course varies, depending on where each planet is in its orbit about the Sun): 1) Round trip: Total distance traveled is d = 2x2 AU = 4AU 2) Convert AU to km, using 1 AU = 1.5x108 km: d = 4 x 1.5x108 km =6x108 km 3) t = d/c = ( 6x108 km ) / (3x105 km/s) = 2x10^3 s Give the answer in seconds in ordinary notation: 2000 (This is 2000/60 = 37 minutes.)

An asteroid is in circular orbit 16 AU from the Sun. What is the period of the asteroid in years?

(64)

How many seconds of arc is 2o?

(7200)

An asteroid is in circular orbit 4 AU from the Sun. What is the period of the asteroid in years?

(8)

A cheetah ran 225 m at 25 m/s. For how many seconds did it run?

(9)

Who measured the Earth's circumference by comparing the height of the Sun in Alexandria to its height in Syene?

(Eratosthenes, eratosthenes)

There is an eclipse on a day when the Moon rises at 6 pm. Is it an eclipse of the Sun or of the Moon?

(Moon)

Suppose the distance from the Sun to an asteroid is 4.5x108km, and the speed of light is 3x105km/s. How long does it take light to travel from the Sun to the asteroid?

1.5x10^3s

A cheetah runs in a straight line at 25 m/s (meters per second). How many meters can it travel in 4 seconds?

100 m/s

Evaluate 10^23/10^12

10^11

The distance from Milwaukee to Buffalo, NY, is about 103 km. What is the distance in meters? (1km=10^3meter)

10^6m

A confused polar bear wakes up 15°S. of the North Pole on December 22 at noon. She looks up and sees Polaris:

15° from zenith

An upscale Martian lander rolls north from the equator of Mars to a point whose latitude is 45oN. If the lander has traveled 2,500 km, what is the circumference of Mars?

20,000 km

The ice planet Hoth has the same radius as the earth but has only half the earth's mass. If you weigh 100 pounds on Earth, how many pounds would you weigh on Hoth?

50

The distance from the Sun to the Earth is about 1.5x10_^8km,and the speed of light is 3x10^5km/s. How long does it take light to travel from the Sun to the Earth?

500 secs

Evaluate 3x10^4x2x10^7

6x10^11

A rock is in circular orbit about the Sun with a radius 4 AU. What is its period?

8 years

A star that rises at 10:00 PM tonight will rise at what time tomorrow night?

9:56

In what month is the Sun closest to the Earth?

January

Which of the following objects has an apparent motion with retrograde loops?

Mars

Which of the following objects can never be seen in an opposite direction in the sky from the sun?

Mercury

From the following names, who first found that gravity could account for the motion of the planets?

Newton

Write 510,000 in powers-of-ten notation.

None of these

Where on Earth are you if the stars appear to move in horizontal circles

North Pole

Can one ever observe an annular eclipse of the Sun? Why or why not?

On can see annular eclipses of the Sun, because the the angular size of the Moon is smaller than the angular size of the Sun when the Moon is farthest from the Earth.

Can one ever observe an annular eclipse of the moon? Why or why not?

One can never see an annular eclipse of the Moon, because the Moon is smaller than the Earth's shadow at the position of the Moon.

Which of the following is not a circumpolar constellation?

Orion

Which of the following objects has an apparent motion with retrograde loops?

all of these Venus Mars Jupiter

A comet in unbound orbit is:

always attracted by the sun's gravity

Two stars in the same constellation

are in roughly the same direction in the sky but not generally at the roughly the same distance from us.

The Sun is directly over the equator on the

at neither solstice

atom is ionized=an electron leaves its atom atom absorbs light=an electron jumps to a higher energy level atom emits light=an electron jumps to a lower energy level

atom is ionized=an electron leaves its atom atom absorbs light=an electron jumps to a higher energy level atom emits light=an electron jumps to a lower energy level

A planet in elliptical orbit moves fastest when it is:

closest

The Earth moves fastest in its orbit when it is

closest to

In the Copernican system, the apparent size of Venus is largest when its phase is

crescent

Galileo's observations of Venus were among the things that showed Ptolemy's model was false and that agreed with the predictions of the Copernican model. In the Copernican system, what phases of Venus do we see?

crescent and gibbous phases

Galileo's observations of Venus were among the things that showed Ptolemy's model was false and that agreed with the predictions of the Copernican model. In Ptolemy's model what phases of Venus would we see? (See the diagram in Chaisson-McMillan.)

crescent only

Mercury's orbit about the Sun has what shape?

ellipse

Pluto's orbit about the Sun has what shape?

ellipse

Where on Earth are you if Polaris is on your horizon?

equator

What is the phase of the moon on the night of a lunar eclipse?

full

The apparent retrograde motion of Jupiter is caused by the:

real revolution of the Earth about the Sun

The apparent retrograde motion of Saturn is caused by the

real revolution of the Earth about the Sun

The shortest night in Milwaukee is on

the summer solstice

The average temperature is hotter in summer than winter. This is ultimately caused by

the tilt of the Earth's axis relative to the Earth's orbit. (The energy emitted by the sun is the same in summer and winter.)

The force on a particle traveling at constant speed in a circle points:

toward the center

You are on skates playing crack-the-whip, and you are the person farthest from the center, your left hand holding the hand of the skater next to you. As you fly around in a circle, you feel your left arm being pulled or pushed in what direction?

toward the center (pulled toward the skater holding your left hand)

If the Moon rises at 4 am, what is its phase?

waning crescent

On a night when the Moon rises at 9 pm, what is its phase?

waning gibbous

The Earth revolves around the Sun once each

year

An asteroid is in circular orbit 3 AU from the sun. Its period of revolution is how many years?

√27