Astronomy 2

Astronomy 2

Which of the following has your “address” in the correct order?
you, Earth, solar system, Milky Way, Local Group, Local Supercluster
About where is our solar system located within the Milky Way Galaxy?
about two-thirds of the way from the center of the galaxy to the outskirts of the galactic disk
Suppose we imagine the Sun to be about the size of a grapefruit. How big an area would the orbits of the eight planets of the solar system cover?
the size of a typical campus
When we look at the most distant observable objects in the universe, we see them
as they were about 14 billion years ago
Earth is made mostly of metals and rocks. Where did this material come from?
It was produced by nuclear fusion in stars.
Which of the following statements does not use the term light-year in an appropriate way?
It will take me light-years to complete this homework assignment.
Suppose we look at a photograph of many galaxies. Assuming that all galaxies formed at about the same time, which galaxy in the picture is the youngest?
the one that is farthest away
What do we mean by the observable universe?
the part of the universe that could be observed in principle, including things that may require
future technologies
Which of the following is smallest?
size of a typical planet
Which of the following is largest?
size of a typical galaxy
Suppose we imagine the Sun to be about the size of a grapefruit. How far away are the nearest stars (the three stars of Alpha Centauri)?
2,500 miles
If the age of the universe were compressed to one year, with the Big Bang on January 1, about when did the solar system form?
in September
If you could count all the stars in the Milky Way Galaxy at a rate of one star per second, it would take
about 3000 years.
Which of the following ranks your different astronomical motions from slowest to fastest?
rotation of Earth; motion of Earth around the Sun; motion of the Sun around the center of the Milky Way
Which of the following statements about the ecliptic plane is not true?
It is the plane of the Moon’s orbit around Earth
Ever since the Big Bang,
space has continued to expand with clusters of galaxies moving away from each other, but stars remaining in galaxies and galaxies remaining in clusters.
The Sun completes one revolution of the Milky Way galaxy every
230,000,000 years.
Earth’s axis of rotation is tilted about 23.5° relative to
the axis of its orbit around the Sun
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
From the fact that virtually every galaxy is moving away from us and more distant galaxies are
moving away from us at a faster rate than closer ones, we conclude that
the universe is expanding.
Which of the following best describes the modern definition of a constellation?
a region of the celestial sphere
Which of the following statements about constellations is false?
Most constellations will be unrecognizable hundreds of years from now
Which of the following statements about the celestial equator is true at all latitudes?
It represents an extension of Earth’s equator onto the celestial sphere.
What is the ecliptic?
the Sun’s apparent path along the celestial sphere
When we look into the band of light in our sky that we call the Milky Way, can we see distant galaxies? Why or why not?
No, because the stars, gas, and dust of the Milky Way block us from seeing them
Which of the following correctly describes the meridian in your sky?
a half-circle extending from your horizon due north, through your zenith, to your horizon due south
How many arcseconds are in 1°?
3,600
Which of the following statements does not use the term angular size or angular distance correctly?
The angular distance between those two bright stars in the sky is about 2 meters.
Which of the following statements about circumpolar stars is true at all latitudes?
They always remain above your horizon.
We describe a position on Earth’s surface by stating its
latitude and longitude.
What makes the North Star, Polaris, special?
It appears very near the north celestial pole.
By locating the north celestial pole (NCP) in the sky, how can you determine your latitude?
The altitude of the NCP is the same as your latitude.
Why do we have seasons on 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 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.
Which of the following statements about lunar phases is true?
It is possible to have two full Moons during January, but not during February.
Which of the following is not a phase of the Moon?
half Moon
If the Moon is setting at 6 A.M., the phase of the Moon must be
full
If the Moon is rising at midnight, the phase of the Moon must be
third quarter
At approximately what time would a full Moon be on your meridian?
midnight
Why do we see essentially the same face of the Moon at all times?
because the Moon’s rotational and orbital periods are equal
Which of the following statements about the Moon is true?
The Moon’s distance from Earth varies during its orbit.
All of the following statements are true. Which one explains the reason why there is not a solar eclipse at every new Moon?
The orbital plane of the Moon is tilted by about 5° to the ecliptic plane.
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 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.
If part of the full Moon passes through Earth’s umbra, we will see a(n)
partial lunar eclipse
What is the Saros cycle?
the 18-year cycle over which the pattern of eclipses repeats
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.
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.
Which of the following statements about parallax is not true?
The technique of stellar parallax was used by Hubble to determine that the Andromeda Galaxy (M 31) is about 2 million light-years away.
The names of the seven days of the week are based on the
seven naked-eye objects that appear to move among the constellations.
Suppose the planet Uranus were much brighter in the sky, so that it was as easily visible to the naked eye as Jupiter or Saturn. Which one of the following statements would most likely be true in that case?
A week would have eight days instead of seven.
In order to tell time at night, the ancient Egyptians of 3000 B.C. used
star clocks, which measured time based on the positions of stars at particular times of night and particular times of year.
Historians trace the origins of a 24-hour day to
the ancient Egyptians.
What 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 observations.
At the Sun Dagger in New Mexico, a dagger-shaped beam of sunlight pierces a spiral
at noon on the summer solstice.
The Muslim fast of Ramadan occurs
during the ninth month of a 12-month lunar cycle.
The path that led to modern science emerged from ancient civilizations in which part of the world?
the Mediterranean and the Middle East
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
Which of the following statements about scientific models is true?
A model can be used to explain and predict real phenomena.
Ptolemy was important in the history of astronomy because he
developed a model of the solar system that made sufficiently accurate predictions of planetary positions to remain in use for many centuries.
How did the Ptolemaic model explain the apparent retrograde motion of the planets?
It held that the planets moved along small circles that moved on larger circles around Earth.
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
During the Dark Ages in Europe, the scientific work of the ancient Greeks was preserved and further developed primarily by scholars in
Baghdad
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
He was the first to prove that comets lie beyond Earth’s atmosphere
Tycho Brahe
He discovered that the orbits of planets are ellipses.
Kepler
He discovered that Jupiter has moons.
Galileo
He discovered what we now call Newton’s first law of motion.
Galileo
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.
Which of the following was not observed by Galileo?
stellar parallax
One of the “nails in the coffin” for Earth-centered universe was
Galileo’s observations of the moons of Jupiter.
Which of the following is not one of, nor follows directly from, Kepler’s laws?
The force of attraction between any two objects decreases with the square of the distance between their centers.
Kepler’s third law, p2 = a3, means that
all orbits with the same semimajor axis have the same period.

the period of a planet does not depend on its mass.

planets that are farther from the Sun move at slower average speeds than nearer planets.

a planet’s period does not depend on the eccentricity of its orbit.

All of the above are correct.

From Kepler’s third law, an asteroid with an orbital period of 8 years lies at an average distance from the Sun equal to
4 astronomical units.
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.
What is meant by a scientific paradigm?
a generally well-established scientific theory or set of theories
What is meant by Occam’s Razor?
the idea that scientists should prefer the simpler of two models that agree equally well with observations
the idea that scientists should prefer the simpler of two models that agree equally well with observations
the idea that scientists should prefer the simpler of two models that agree equally well with observations
The amount of time between successive passes of the star Sirius across the meridian is
23 hours 56 minutes.
Which of the following statements about sidereal and solar days is not true?
The time it takes for the Moon to make one circuit of our sky is one solar day.
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
The lunar month is longer than the sidereal month because
the Moon has to complete more than one full orbit around Earth to complete the cycle of lunar phases.
What kind of time can be read directly from a sundial?
apparent solar time
Which of the following is the reason for the leap years?
Earth year being a non-integer number of Earth days
The Sun is rising in the east and will be on your meridian in 2 hours. What time is it?
10 A.M
Suppose you lived at Earth’s equator. Which of the following statements would not be true?
The celestial equator goes through your sky from due east on your horizon, through 50° altitude in the south, to due west on the horizon.
The south celestial pole appears on your meridian at an altitude of 30° in the south. Where are you?
latitude = 30°S
The time between rising and setting of a star
depends on the observer’s latitude.
Suppose you live at latitude 40°N. Which of the following describes the conditions that make a star circumpolar?
Stars are circumpolar if they have declination > +50°.
Which of the following best describes the Tropic of Cancer?
It is a place where the Sun is directly overhead at noon on the summer solstice
Suppose the date is March 21 and the Sun passes through your zenith at noon. Where are you?
the equator
Suppose the date is June 21 and the Sun never sets, just touching your northern horizon at midnight. Where are you?
the Arctic Circle
Which of the following explains why navigators a few hundred years ago found it much more difficult to determine their longitude than their latitude?
Determining longitude requires having an accurate clock
The Sun is on your meridian, and you have a UT clock that tells you it is 3 P.M. in Greenwich. What is your longitude?
45° west of Greenwich
The constellation shaped like a big square (the “great square of . . . “) is
Pegasus.
The constellation shaped like a W is
Cassiopeia
Which of the following statements about Betelgeuse is not true?
Its Arabic name means “the demon star.”
Each of the following lists a constellation and a bright star. In all cases but one, the star is part of the constellation. Which one is the mismatch?
Scorpio, Vega