Astronomy 2 – Flashcards
Unlock all answers in this set
Unlock answersquestion
Which of the following has your "address" in the correct order?
answer
you, Earth, solar system, Milky Way, Local Group, Local Supercluster
question
About where is our solar system located within the Milky Way Galaxy?
answer
about two-thirds of the way from the center of the galaxy to the outskirts of the galactic disk
question
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?
answer
the size of a typical campus
question
When we look at the most distant observable objects in the universe, we see them
answer
as they were about 14 billion years ago
question
Earth is made mostly of metals and rocks. Where did this material come from?
answer
It was produced by nuclear fusion in stars.
question
Which of the following statements does not use the term light-year in an appropriate way?
answer
It will take me light-years to complete this homework assignment.
question
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?
answer
the one that is farthest away
question
What do we mean by the observable universe?
answer
the part of the universe that could be observed in principle, including things that may require future technologies
question
Which of the following is smallest?
answer
size of a typical planet
question
Which of the following is largest?
answer
size of a typical galaxy
question
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)?
answer
2,500 miles
question
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?
answer
in September
question
If you could count all the stars in the Milky Way Galaxy at a rate of one star per second, it would take
answer
about 3000 years.
question
Which of the following ranks your different astronomical motions from slowest to fastest?
answer
rotation of Earth; motion of Earth around the Sun; motion of the Sun around the center of the Milky Way
question
Which of the following statements about the ecliptic plane is not true?
answer
It is the plane of the Moon's orbit around Earth
question
Ever since the Big Bang,
answer
space has continued to expand with clusters of galaxies moving away from each other, but stars remaining in galaxies and galaxies remaining in clusters.
question
The Sun completes one revolution of the Milky Way galaxy every
answer
230,000,000 years.
question
Earth's axis of rotation is tilted about 23.5° relative to
answer
the axis of its orbit around the Sun
question
Which scientists played a major role in overturning the ancient idea of an Earth-centered universe, and about when?
answer
Copernicus, Kepler, and Galileo; about 400 years ago
question
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
answer
the universe is expanding.
question
Which of the following best describes the modern definition of a constellation?
answer
a region of the celestial sphere
question
Which of the following statements about constellations is false?
answer
Most constellations will be unrecognizable hundreds of years from now
question
Which of the following statements about the celestial equator is true at all latitudes?
answer
It represents an extension of Earth's equator onto the celestial sphere.
question
What is the ecliptic?
answer
the Sun's apparent path along the celestial sphere
question
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?
answer
No, because the stars, gas, and dust of the Milky Way block us from seeing them
question
Which of the following correctly describes the meridian in your sky?
answer
a half-circle extending from your horizon due north, through your zenith, to your horizon due south
question
How many arcseconds are in 1°?
answer
3,600
question
Which of the following statements does not use the term angular size or angular distance correctly?
answer
The angular distance between those two bright stars in the sky is about 2 meters.
question
Which of the following statements about circumpolar stars is true at all latitudes?
answer
They always remain above your horizon.
question
We describe a position on Earth's surface by stating its
answer
latitude and longitude.
question
What makes the North Star, Polaris, special?
answer
It appears very near the north celestial pole.
question
By locating the north celestial pole (NCP) in the sky, how can you determine your latitude?
answer
The altitude of the NCP is the same as your latitude.
question
Why do we have seasons on Earth?
answer
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.
question
Why is it summer in the Northern Hemisphere when it is winter in the Southern Hemisphere?
answer
The Northern Hemisphere is tilted toward the Sun and receives more direct sunlight.
question
Which of the following statements about lunar phases is true?
answer
It is possible to have two full Moons during January, but not during February.
question
Which of the following is not a phase of the Moon?
answer
half Moon
question
If the Moon is setting at 6 A.M., the phase of the Moon must be
answer
full
question
If the Moon is rising at midnight, the phase of the Moon must be
answer
third quarter
question
At approximately what time would a full Moon be on your meridian?
answer
midnight
question
Why do we see essentially the same face of the Moon at all times?
answer
because the Moon's rotational and orbital periods are equal
question
Which of the following statements about the Moon is true?
answer
The Moon's distance from Earth varies during its orbit.
question
All of the following statements are true. Which one explains the reason why there is not a solar eclipse at every new Moon?
answer
The orbital plane of the Moon is tilted by about 5° to the ecliptic plane.
question
What conditions are required for a solar eclipse?
answer
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.
question
What conditions are required for a lunar eclipse?
answer
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.
question
If part of the full Moon passes through Earth's umbra, we will see a(n)
answer
partial lunar eclipse
question
What is the Saros cycle?
answer
the 18-year cycle over which the pattern of eclipses repeats
question
What happens during the apparent retrograde motion of a planet?
answer
The planet appears to move eastward with respect to the stars over a period of many nights.
question
What causes the apparent retrograde motion of the planets?
answer
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.
question
Which of the following statements about parallax is not true?
answer
The technique of stellar parallax was used by Hubble to determine that the Andromeda Galaxy (M 31) is about 2 million light-years away.
question
The names of the seven days of the week are based on the
answer
seven naked-eye objects that appear to move among the constellations.
question
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?
answer
A week would have eight days instead of seven.
question
In order to tell time at night, the ancient Egyptians of 3000 B.C. used
answer
star clocks, which measured time based on the positions of stars at particular times of night and particular times of year.
question
Historians trace the origins of a 24-hour day to
answer
the ancient Egyptians.
question
What do the structures of Stonehenge, the Templo Mayor, the Sun Dagger, and the Big Horn Medicine Wheel all have in common?
answer
They were all used by ancient peoples for astronomical observations.
question
At the Sun Dagger in New Mexico, a dagger-shaped beam of sunlight pierces a spiral
answer
at noon on the summer solstice.
question
The Muslim fast of Ramadan occurs
answer
during the ninth month of a 12-month lunar cycle.
question
The path that led to modern science emerged from ancient civilizations in which part of the world?
answer
the Mediterranean and the Middle East
question
How did Eratosthenes estimate the size of Earth in 240 B.C.?
answer
by comparing the maximum altitude of the Sun in two cities at different latitudes
question
Which of the following statements about scientific models is true?
answer
A model can be used to explain and predict real phenomena.
question
Ptolemy was important in the history of astronomy because he
answer
developed a model of the solar system that made sufficiently accurate predictions of planetary positions to remain in use for many centuries.
question
How did the Ptolemaic model explain the apparent retrograde motion of the planets?
answer
It held that the planets moved along small circles that moved on larger circles around Earth.
question
Why did Ptolemy have the planets orbiting Earth on "circles upon circles" in his model of the universe?
answer
to explain the fact that planets sometimes appear to move westward, rather than eastward, relative to the stars in our sky
question
During the Dark Ages in Europe, the scientific work of the ancient Greeks was preserved and further developed primarily by scholars in
answer
Baghdad
question
The controversial book of this famous person, published in 1543 (the year of his death), suggested that Earth and other planets orbit the Sun.
answer
Copernicus
question
He was the first to prove that comets lie beyond Earth's atmosphere
answer
Tycho Brahe
question
He discovered that the orbits of planets are ellipses.
answer
Kepler
question
He discovered that Jupiter has moons.
answer
Galileo
question
He discovered what we now call Newton's first law of motion.
answer
Galileo
question
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?
answer
Copernicus used perfect circles for the orbits of the planets.
question
Which of the following was not observed by Galileo?
answer
stellar parallax
question
One of the "nails in the coffin" for Earth-centered universe was
answer
Galileo's observations of the moons of Jupiter.
question
Which of the following is not one of, nor follows directly from, Kepler's laws?
answer
The force of attraction between any two objects decreases with the square of the distance between their centers.
question
Kepler's third law, p2 = a3, means that
answer
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.
question
From Kepler's third law, an asteroid with an orbital period of 8 years lies at an average distance from the Sun equal to
answer
4 astronomical units.
question
Kepler's second law, which states that as a planet moves around its orbit it sweeps out equal areas in equal times, means that
answer
a planet travels faster when it is nearer to the Sun and slower when it is farther from the Sun.
question
What is meant by a scientific paradigm?
answer
a generally well-established scientific theory or set of theories
question
What is meant by Occam's Razor?
answer
the idea that scientists should prefer the simpler of two models that agree equally well with observations
question
the idea that scientists should prefer the simpler of two models that agree equally well with observations
answer
the idea that scientists should prefer the simpler of two models that agree equally well with observations
question
The amount of time between successive passes of the star Sirius across the meridian is
answer
23 hours 56 minutes.
question
Which of the following statements about sidereal and solar days is not true?
answer
The time it takes for the Moon to make one circuit of our sky is one solar day.
question
Which of the following is the reason for the solar day being longer than a sidereal day?
answer
the combined effect of the rotation of Earth and its orbit about the Sun
question
The lunar month is longer than the sidereal month because
answer
the Moon has to complete more than one full orbit around Earth to complete the cycle of lunar phases.
question
What kind of time can be read directly from a sundial?
answer
apparent solar time
question
Which of the following is the reason for the leap years?
answer
Earth year being a non-integer number of Earth days
question
The Sun is rising in the east and will be on your meridian in 2 hours. What time is it?
answer
10 A.M
question
Suppose you lived at Earth's equator. Which of the following statements would not be true?
answer
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.
question
The south celestial pole appears on your meridian at an altitude of 30° in the south. Where are you?
answer
latitude = 30°S
question
The time between rising and setting of a star
answer
depends on the observer's latitude.
question
Suppose you live at latitude 40°N. Which of the following describes the conditions that make a star circumpolar?
answer
Stars are circumpolar if they have declination > +50°.
question
Which of the following best describes the Tropic of Cancer?
answer
It is a place where the Sun is directly overhead at noon on the summer solstice
question
Suppose the date is March 21 and the Sun passes through your zenith at noon. Where are you?
answer
the equator
question
Suppose the date is June 21 and the Sun never sets, just touching your northern horizon at midnight. Where are you?
answer
the Arctic Circle
question
Which of the following explains why navigators a few hundred years ago found it much more difficult to determine their longitude than their latitude?
answer
Determining longitude requires having an accurate clock
question
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?
answer
45° west of Greenwich
question
The constellation shaped like a big square (the "great square of . . . ") is
answer
Pegasus.
question
The constellation shaped like a W is
answer
Cassiopeia
question
Which of the following statements about Betelgeuse is not true?
answer
Its Arabic name means "the demon star."
question
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?
answer
Scorpio, Vega
