What do we mean when we say the universe is expanding?
Average distances are increasing between galaxies.
How are galaxies important to our existence?
Galaxies recycle heavy elements produced in stars into future generations of stars
The number of stars in the milky way galaxy is approximately
A few hundred billion.
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.
Which of the following correctly lists speeds from the slowest to fastest?
Earth's speed of rotation on its axis, Earth's speed of revolution about the Sun, typical speeds of stars in the local solar neighborhood relative to us, the speed of our solar system orbiting the center of the Milky Way Galaxy, the speeds of very distant galaxies relative to us.
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.
Our solar system consists of
The sun and all the objects that orbit it.
On a cosmic calender, in which the history of the universe is compressed into 1 year, when did the dinosaurs become extinct?
In late december.
Astronomers infer that the universe is expanding because distant galaxies all appear to
be moving away from us, with more distant ones moving faster.
Patterns of stars in constellations hardly change in appearance over times of even a few thousand years. Why?
The stars in our sky actually move rapidly relative to us-thousands of kilometers per hour-but are so far away that it takes a long time for this motion to make a noticeable change in the patterns in the sky.
Which of the following best describes the Milky Way Galaxy?
A spiral galaxy with a disk about 100,000 light-years in diameter and containing between 100 billion and 1 trillion stars.
Approximately how fast are you moving with the rotation of the earth
On the 1-to-10 billion scale, about how far is it to the nearest stars besides the sun?
Why does carl sagan say that we are star stuff?
Nearly every atom from which we are made once (before the solar system formed) was inside of a star.
Based on observations of the universal expansion, the age of the universe is about
14 billion years.
On the scale of the cosmic calendar, in which the history of the universe is compressed to 1 year, how long has human civilization (i.e., since Egypt) existed?
A few seconds.
What is the sun mainly made of
hydrogen and helium
Which of the following has your "address" in the correct order
you, earth, solar system, Milky Way, Local Group, Local Supercluster
What is a nuclear fusion?
The process of combining lightweight nuclei to make heavier nuclei.
A television advertisement claiming that a product is light-years ahead of its time does not make sense because
It uses "light-years" to talk about time, but a light-year is a unit of distance.
How long does it take our solar system to complete one orbit around the Milky Way Galaxy?
230 million years.
Most of the mass in the Milky Way Galaxy is located
in the halo (above/below the disk).
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 assisgnment
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.
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.
What effect or effects would be most significant if the moon's orbital plane were exactly the same as the ecliptic plane?
Solar eclipses would be much more frequent.
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.
Suppose you live in the United States and you see a crescent Moon in your evening sky tonight, what will a friend in south America see tonight
Your friend will also see a crescent Moon.
How does Earth's varying distance from the Sun affect our seasons?
It doesn't-Earth's orbital distance plays no significant role in the seasons.
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.
Which of the following statements about the celestial sphere is NOT true?
The "celestial sphere" is another name for our universe.
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.
When are eclipse seasons?
When the nodes of the Moon's orbit are nearly aligned with the Sun.
Suppose you use the Southern Cross to determine that the south celestial pole appears 40 degrees above your horizon. Then you must be located at
latitude 40 degrees south.
During the time that a planet is in its period of apparent retrograde motion,
over many days or weeks, the planet moves westward relative to the stars, rather than the usual eastward relative to the stars.
We can't detect stellar parallax with naked-eye observations. Which of the following would make parallax easier to observe?
Increasing the size of Earth's orbit.
All of the following statements are true. Which one explains the reason that there is not a solar eclipse at every new moon?
The orbital plane of the Moon is tilted slightly (by about 5 degrees) to the ecliptic plane.
What is a circumpolar star?
A star that always remains above your horizon.
How does a 12-month lunar calendar differ from our 12-month solar calender?
It has about 11 fewer days.
All of the following statements are true. Which one follows directly from Kepler's third law (p^2=a^3)
Venus orbits the Sun at a slower average speed than Mercury.
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.
The astrology practiced by those who cast predictive horoscopes can be tested by
Comparing how often the prediction comes true to what would be expected by pure chance.
The ancient Greeks get a lot of attention for their contributions to science because
They were the first people known to try to explain nature with models based on reason and mathematics, without resort to the supernatural.
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
Which of the following is not consistent with the major hallmarks of science?
Science consists of proven theories that are understood to be true explanations of reality.
Which of the following statements about scientific theories is not true?
A theory cannot be taken seriously by scientists if it contradicts other theories developed by scientists over the past several hundred years.
What do scientists mean by verifiable observations
Statements that a person can, in principle, verify for himself or herself.
What is meant by scientific paradigm
a generally well-established scientific theory or set of theories.
The age of the universe is
between 10 billion and 16 billion years.
What do astronomers mean by the big bang?
The event that marked the beginning of the expansion of the universe.
Which of the following statements about the Milky way Galaxy is not true?
Our solar system is located very close to the center of the Milky Way Galaxy.
What do we mean when we say that the universe is expanding?
Average distances between galaxies are increasing with time.
How are galaxies important to our existence?
Galaxies recycle material from one generation of stars to the next, and without this recycling would could not exist.
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.
Which of the following has your "cosmic address" in the correct order?
You, Earth, solar system, Milky Way Galaxy, Local Group, Local Supercluster, Universe.
You observe a full Moon rising at sunset. What will you see at midnight?
a full moon high in the sky.
Suppose you live on the moon. How long is a day (ie, from sunrise to sunrise)
a lunar month.
Which of the following correctly describes the meridian in your local sky?
a half-circle extending from your horizon due north, through your zenith, to your horizon due south.
We cannot see a new moon in our sky because
A new moon is quite near the Sun in the sky.
Which of the following is not a phase of the Moon?
Must acupuncture be responsible for the patients recovery?
No. Acupuncture may be responsible for the healing, or it may not. Correlation does not necessarily imply causation.
Which of the following best describes how modern astronomers view astrology?
Astrology played an important part in the development of astronomy in ancient times, but it is not the science by modern standards.
When did Ptolemy live?
About 2000 years ago.
How long would it take to count all the stars in the Milky Way Galaxy at a rate of one star per second?
Several thousand years.
A typical galaxy is a
collection of a few hundred million to a trillion or more stars, bound together by gravity.
Stars that are visible in the local sky on any clear night of the year, at any time of the night, are called
He was the first to prove that comets lie beyond Earth's atmosphere.
Suppose we imagine the Sun to be about the size of a grapefruit. Which of the following describes the size and distance of Earth on the same scale.
Earth is the size of a point about 15 meters away from the Sun.
It's 6 a.m. and the Moon is at its highest point in your sky (crossing the meridian). What is the Moon's phase?
Earth is farthest from the Sun in July? and closest to the Sun in January. During which Northern Hemisphere season is Earth moving fastest in its orbit