About how many stars are visible to the naked eye on a clear, dark night away from city lights?
A couple thousand
What do astronomers mean by a constellation?
A constellation is a region in the sky as seen from Earth.
What is the ecliptic?
The path the Sun appears to trace around the celestial sphere each year
What is the celestial sphere?
The celestial sphere is a representation of how the entire sky looks as seen from Earth.
What do we mean when we talk about the Milky Way in our sky?
The patchy band of light that outlines the plane of the Milky Way Galaxy as seen from Earth.
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 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
The point directly over your head is called _________.
Stars that are visible in the local sky on any clear night of the year, at any time of the night, are called _________.
We describe a location on Earth's surface by stating its _________.
latitude and longitude
If you are located in the Northern Hemisphere, which of the following correctly describes a relationship between the sky and your location?
The altitude of the north celestial pole equals your latitude.
Which of the following best describes why we have seasons on Earth?
The tilt of Earth's axis causes different portions of the Earth to receive more or less direct sunlight at different times of year.
Each choice below describes how a few astronomical phenomena are related to time periods. Which list is entirely correct? (Careful: some lists are partially correct.)
Earth's rotation defines a day. The cycle of the Moon's phases takes about a month. Earth's orbit defines a year. Earth's cycle of axis precession takes 26,000 years.
If we have a new moon today, when we will have the next full moon?
In about 2 weeks
We cannot see a new moon in our sky because _________.
a new moon is quite near the Sun in the sky
The Moon always shows nearly the same face to Earth because ________.
the Moon rotates once in the same amount of time that it takes the Moon to orbit Earth once
Lunar eclipses can occur only during a _________.
full moon
What is the saros cycle?
The roughly 18-year cycle over which the pattern of eclipses repeats
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
What is stellar parallax?
It is the slight back-and-forth shifting of star positions that occurs as we view the stars from different positions in Earth's orbit of the Sun.
Which of the following statements about the celestial sphere is NOT true?
The "celestial sphere" is another name for our universe.
The Andromeda Galaxy is faintly visible to the naked eye in the constellation Andromeda. Suppose instead it were located in the same direction in space as the center of the Milky Way Galaxy (but still at its current distance). How would it appear to the eye in that case?
We could not see it at all.
An angle of 1 arcsecond is _________.
about the width of your fist held at arm's length
When traveling north from the United States into Canada, you'll see the North Star (Polaris) getting _________.
higher in the sky
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 _________.
longitude 40 degrees
Suppose you are facing north and you see the Big Dipper close to your northern horizon, with Polaris (and the Little Dipper) above it. Where will you see the Big Dipper in six hours?
Directly above Polaris
In any particular place on Earth, certain constellations are visible in the evening only at certain times of the year because _________.
our evening view of space depends on where Earth is located in its orbit around the Sun.
The Sun's path, as viewed from the equator, is highest in the sky on _________.
the spring and fall equinoxes
Suppose Earth's axis tilt was significantly greater than its current 23.5 degrees, but Earth's rotation period and orbital period were unchanged. Which statement below would not be true?
The length of each season (for example, the number of days from the summer solstice to the fall equinox) would be significantly longer than it is now.
If our year were twice as long (that is, if Earth took twice as many days to complete each orbit around the Sun), but Earth's rotation period and axis tilt were unchanged, then _________.
the four seasons would each be twice as long as they are now
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.
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.
Suppose it is full moon. What phase of Earth would someone on the Moon see at this time?
New Earth
It's 6 am and the Moon is at its highest point in your sky (crossing the meridian). What is the Moon's phase?
third quarter
You observe a full moon rising at sunset. What will you see at midnight?
A full moon high in the sky
All 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.
For most of history, the lack of observable stellar parallax was interpreted to mean that _________.
Earth is stationary at the center of the universe
During the period each year when we see Mars undergoing apparent retrograde motion in our sky, what is really going on in space?
Earth is catching up with and passing by Mars in their respective orbits.