Download PHYS 2410 General Astronomy Homework 1

PHYS 2410
General Astronomy
Homework 1
Due 9/23 before the classes
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Multiple Choice (單選題!)
1.
If the size of the Sun is represented by a baseball with the Earth is about 15 meters away, how far
away, to scale, would the nearest stars to the Sun be?
*
2.
*
3.
*
4.
a.
About the distance between New York and Boston.
b.
100 meters away
c.
About the distance across the United States.
d.
About the distance across 50 football fields.
A solar system contains
a.
primarily planets.
b.
large amounts of gas and dust but very few stars.
c.
large amounts of gas, dust, and stars.
d.
a single star and planets.
e.
thousands of superclusters.
A galaxy contains
a.
primarily planets.
b.
large amounts of gas and dust but very few stars.
c.
large amounts of gas, dust, and stars.
d.
a single star and planets.
e.
thousands of superclusters.
If light takes 8 minutes to reach Earth from the sun and 5.3 hours to reach Pluto, what is the
approximate distance from the sun to Pluto?
*
5.
*
a.
5.3 AU
b.
40 AU
c.
40 ly
d.
5.3 ly
e.
0.6 ly
If the nearest star is 4.2 light-years away, then
a.
the star is 4.2 million AU away.
b.
the light we see left the star 4.2 years ago.
6.
*
7.
c.
the star must have formed 4.2 billion years ago.
d.
the star must be very young.
e.
the star must be very old.
If the nearest star is 4.2 light-years away, then
a.
the star is 4.2 million AU away.
b.
the light we see left the star 4.2 years ago.
c.
the star must have formed 4.2 billion years ago.
d.
the star must be very young.
e.
the star must be very old.
Suppose we wish to travel to the nearest star using a super space ship capable of traveling at
1x1010
km/yr.
We have nothing even close to this space ship yet.
13
get to the nearest star which is about 4 x10 km away from us?
*
a.
4 years
b.
400 years
c.
4000 years
d.
4 billion years
8.
If we say that an object is 1,000 light-years away we see it
*
a.
as it looked 1,000 years ago.
b.
as it would appear to our ancestors 1,000 years ago.
c.
as it looked 1,000 light-years ago.
d.
as it is right now, but it appears 1,000 times dimmer.
9.
*
A constellation must consist of a number of stars, all
a.
at the same distance from the Earth.
b.
at various different distances from the Earth.
c.
within a boundary in the same general angular area of the sky.
d.
Wrong!
Constellations are made of planets only.
10. ___________ is the brightest star in the constellation of Ursa Majoris.
*
a.
βUr
s
aMa
j
or
i
s
b.
γUr
s
aMa
j
or
i
s
c.
αUr
s
aMa
j
or
i
s
d.
Wrong!
Ursa Majoris is the name of the brightest star.
11. The magnitude scale
How long will it take us to
*
a.
originated just after the telescope was invented.
b.
can be used to indicate the apparent intensity of a celestial object.
c.
is used to measure the temperature of a star.
d..
was used to determine the rate of precession.
12. The apparent visual magnitude of a star is 7.3.
*
This tells us that the star is
a.
one of the brighter stars in the sky.
b.
bright enough that it would be visible even during the day.
c.
not visible with the unaided eye.
d.
very close to Earth.
13. The apparent visual magnitude of a star is a measure of the star's
*
a.
size.
b.
intensity.
c.
distance.
d.
color.
e.
temperature.
14. The apparent visual magnitude of a star is 7.3.
*
This tells us that the star is
a.
one of the brighter stars in the sky.
b.
bright enough that it would be visible even during the day.
c.
not visible with the unaided eye.
d.
very close to Earth.
15. The apparent visual magnitude of a star is a measure of the star's
*
Star
Apparent Visual
Name
Magnitude
a.
size.
Dra
3.07
b.
intensity.
 Cet
2.53
c.
distance.
Per
3.98
d.
color.
Nim
8.07
e.
temperature.
 CMa
-1.46
16. Polaris is a second magnitude star, and Phi Pegasi is about 16 times fainter than Polaris.
the approximate magnitude of Phi Pegasi?
a.
18
b.
-14
c.
3
What is
*
d.
-3
e.
5
17. The star Vega has an apparent visual magnitude of 0.03, and the star HR 4374 has an apparent
visual magnitude of 4.87.
Earth.
*
It has been determined that both stars are at the same distance from
What does this information tell us about the two stars?
a.
Vega must be closer to Earth than HR 4374.
b.
Vega must be farther from Earth than HR 4374.
c.
Vega must produce less energy than HR 4374.
d.
Vega must produce more energy than HR 4374.
e.
Vega will appear fainter to us than HR 4374.
18. An observer on Earth's equator would find
*
a.
Polaris directly overhead.
b.
Polaris 40° above the northern horizon.
c.
that the celestial equator coincides with the horizon.
d.
the celestial equator passing directly overhead.
e.
that the ecliptic coincides with the horizon.
19. The celestial equator is
*
a.
a line around the sky directly above Earth's equator.
b.
the dividing line between the north and south celestial hemispheres.
c.
the path that the sun appears to follow on the celestial sphere as Earth orbits the sun.
d.
a and b.
e.
a and c.
20. An observer in the Northern Hemisphere watches the sky for several hours.
Due to the motion of
Earth, this observer notices that the stars near the north celestial pole appear to move
*
a.
counter clockwise.
b.
clockwise.
c.
from left to right.
d.
from right to left.
e.
nearly vertically upward.
21. You live at a latitude of 73° N.
celestial pole?
*
a.
73°
b.
27°
c.
17°
What is the angle between the northern horizon and the north
d.
23½°
e.
5°
22. You live at a latitude of 39° S.
What is the angle between the southern horizon and the south
celestial pole?
*
a.
45°
b.
23.5°
c.
39°
d.
51°
e.
The answer depends on the day of the year.
23. Which of the following causes seasons on the earth?
*
a.
the earth being closer to the sun during our summer and farther during our winter
b.
the sun's varying light output
c.
the tilt of the earth's axis
d.
the eleven-year sunspot cycle
24. As seen from the earth, the sun appears to move ____________ along the ________ among the
stars.
*
a.
eastward, celestial equator
b.
westward, celestial equator
c.
eastward, ecliptic
d.
westward, ecliptic
e.
Wrong!
The sun does not appear to move among the stars.
25. If the Sun passes directly overhead on at least one day per year, then
*
a.
you are within 23½° latitude of the equator.
b.
you are within 66½° latitude of the equator.
c.
you must be exactly on the equator.
d.
you could be anywhere because this occurs at least once per year at any location on the Earth.