Astronomy Ch. 2
What do astronomers mean by a constellation?
A constellation is a region in the sky as seen from Earth.
About how many stars are visible to the naked eye on a clear, dark night away from city lights?
A couple thousand
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
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.
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.
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
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
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.
What is the ecliptic?
The path the Sun appears to trace around the celestial sphere each year
What is the saros cycle?
The roughly 18-year cycle over which the pattern of eclipses repeats
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.
We cannot see a new moon in our sky because _________.
a new moon is quite near the Sun in the sky
If we have a new moon today, when we will have the next full moon?
about 2 weeks
Stars that are visible in the local sky on any clear night of the year, at any time of the night, are called _________.
circumpolar
Lunar eclipses can occur only during a _________.
full moon
We describe a location on Earth's surface by stating its _________.
latitude and longitude
The point directly over your head is called _________.
zenith
