Astronomy CH.2 Study Guide
The latitude of Earth's equator is
0 degrees
The angular size of your finger at arm's length is about 1°. How many arcseconds is this?
3600 arcseconds
If you were on the Moon, Earth would
Show phases opposite to the Moon (when it is full Moon it is new Earth, etc.)
Earth's actual rotation period
Sidereal day
What are the cycle of seasons like at the North Pole?
Six months of light, followed by six months of darkness (or at least dark twlight)
The amount of time needed for the same part of the earth to once again point towards the sun
Solar day
When the earth blocks sunlight from reaching the moon (either entirely or partially).
Solar eclipse
The time when the northern hemisphere gets the most direct sunlight
Summer solstice
Rank the following sky phenomena (things that happen in the sky) by how frequently we see them from any one location on Earth, from most frequent to least frequent.
Sunrise Full Moon A day when the daylight and darkness are the same Total lunar eclipse Total solar eclipse
If you had a very fast spaceship, you could travel to the celestial sphere in about a month.
This statement doesn't make sense because the celestial sphere is a concept and not a physical object.
For us in the US, the time when the southern hemisphere points most directly toward the sun
Winter solstice
The point in the sky directly above your head at any given time is called the
zenith
A line passing through the zenith connecting the north and south points on the horizon
Meridian
Why is there a 4-minute difference between the solar day and the sidereal day?
Because the Earth is going around the Sun in the course of the year
During what phase of the Moon is the Moon up only during the night hours and all night long?
Full moon
What phase of the Moon must it be to have a lunar eclipse?
Full moon
A woman lives at latitude 64 degrees in the NH - How high above the horizon is the north pole? - How far is it from the north pole to the zenith?
64, 26
The time it takes for the Sun to return to the same place in our sky after the Earth has rotated once
A solar day
During the period we have daylight savings time, we
Add one hour to local standard time
How high above the horizon something is in the sky
Altitude
The appearance of planets moving backwards across the sky
Apparent retrograde motion
1/60 of a degree in the sky
Arcminute
1/60 of an arcminute in the sky
Arcsecond
If you could see the new moon, at what time of day (roughly) would it rise?
At sunrise
From a U.S. city, where in the sky would you look to see a star that is not turning with the motion of the sky in the course of the night?
At the north celestial pole
Where on Earth do stars always circle the zenith and never rise and set?
At the north pole
The direction towards something, where 0 degrees corresponds to north increasing counterclockwise from there
Azimuth
The "prime meridian" passes through
Greenwich, England
On the celestial sphere, halfway between the celestial pole lies the
Celestial equator
One of the 88 regions covering the celestial sphere
Constellation
The 88 sectors into which astronomers today divide the celestial sphere ( the whole sky) are called
Constellations
Objects are located on the celestial sphere in units of:
Degrees
(Pick two) The times when the sun shines equally on both hemispheres.
Fall (autumnal) equinox Spring (vernal) equinox
All points 90 degrees away from directly overhead; the line where all points below it are blocked by sight from the earth
Horizon
At the Earth's North Pole, the celestial equator would be at your
Horizon
When an astronomer describes the altitude of something in the local sky, he or she means:
How high above the horizon something is in the sky
In Australia when are the days the shortest and the nights the longest?
In late June
What causes the seasons?
In summer, the Sun climbs higher in the sky so its rays hit the ground more directly The Sun is up for more hours
What makes Polaris special?
It is near the axis about which the sky turns Its azimuth (direction) is always due north
Why is it generally warmer a month or so after the summer solstice than it is on the solstice itself
It takes time for the Earth to warm up and cool down.
Suppose that the Moon was a cube, but everything else was the same-it kept one side facing Earth as it orbited. What would its phases be like?
It would only show "new" and "full" phases
The number of degrees of arc that your location is north or south of the Earth's equator is called your
Latitude
Your position north or south of the equator.
Latitude
The altitude (height in degrees above the horizon) of the North Start is always roughly equal to the
Latitude of the observer
The number of degrees east or west of the Greenwich Meridian is called
Longitude
Your position west or east of the prime meridian.
Longitude
When the moon blocks sunlight from reaching the earth (either entirely or partially).
Lunar eclipse
As seen from North America, stars near Polaris in the sky...
Never set
What phase of the Moon must it be to have a solar eclipse?
New moon
How often can there be a solar eclipse (at any point on the earth)
Once every few decades
Directly above Earth's north pole, on the celestial sphere, is
Polaris
The star that is currently closest to the North Celestial Pole is
Polaris
The slow tipping of the Earth's axis in a circle with a period of about 26,000 years is called
Precession
The full moon is at its highest point in the sky. What time of day is this?
Roughly midnight
What day is day and night the same length?
September 23
The cycle of day and night is because of
The Earth turns
Why does the Moon look reddish to us when there is a total lunar eclipse?
The Earth's atmosphere bends different colors of light to a different degree. During a total lunar eclipse, the red light of the Sun, filtering through the Earth's atmosphere colors the Moon red
The south celestial pole and the north celestial pole lie in the sky directly above
The Earth's axis
The different amounts of daylight during the cycle of the seasons happens because
The Earth's axis is tilted
If the Earth goes around the Sun, why is the ecliptic not lined up with the celestial equator?
The Earth's axis is titled by about 23 degrees from the vertical
Why was the problem of devising a workable yearly calendar so difficult on Earth?
The Earth's rotation period does not divide evenly into the Earth's period of revolution
Which celestial object has the fastest apparent motion in the sky?
The Moon
Which of the following is NOT an argument for showing that the Earth must be round
The Sun is seen blocking different constellations in the course of the year
Why is it hotter in the Summer than in the Winter?
The Sun's rays hit the Earth more directly in the Summer, and spread out less
Why does the Moon show phases in the course of a month?
The angle the Moon makes with the Sun changes and we see differing amounts of reflected sunlight
Define declination
The angular distance of a point north or south of the celestial equator.
A projection of the equator out into space
The celestial equator
A way of describing the appearance of the sky from the earth
The celestial sphere
When an astronomer describes the azimuth of something in the local sky, he or she means:
The direction toward something, such as north, south, east, or west, in units of degrees
The Sun's apparent path around the celestial sphere is called
The ecliptic
The apparent path of the sun through the celestial sphere
The ecliptic
Where on Earth is summer and winter not that different
The equator
The phases of the Moon happen because
The moon orbits the Earth
Eclipses don't happen every month because
The moon's orbit is titled relative to the ecliptic
The point directly above the earth's north pole
The north celestial pole
Define right ascension
The number of degrees along the celestial equator a particular point is eastward of the vernal equinox
If the tilt of Earth's axis to its orbital plane was 40 degrees, instead of 23 and a half, but its distance from the Sun remained the same, what would happen to the seasons?
They would become more extreme- winter colder and summer warmer
The celestial sphere turns once around each day because
The planet on which we live is rotating
The period of the moon's rotation on its axis is
The same as its revolution around the Earth
The point directly above the earth's south pole
The south celestial pole
Which of the following is NOT a result of the Earth's precession
The stars twinkle when seen from the surface of planet Earth
How did the world's countries solve the problem that mean solar time varies continuously as a traveler's longitude changes?
The world was divided into 24 time zones, with all communities within a time zone keeping the same mean standard time
At the Earth's equator you would see one point of the celestial equator pass through your
Zenith
The point directly overhead where you are at
Zenith
A map of the entire sky is called:
celestial sphere
The sky is divided into 88 zones called
constellations
The brightest stars in a constellation
may actually be quite far away from each other