ASTRO 5 Midterm Exam UPDATED
ACTUAL Exam Questions and CORRECT
Answers
Horizon - CORRECT ANSWER - A circular boundary between the ground and sky
Zenith - CORRECT ANSWER - A point in the sky directly above the observer
Altitude always = 90
Celestial Meridian - CORRECT ANSWER - An arc connecting the North and South
points on the Horizon and passing through the Zenith
Altitude - CORRECT ANSWER - The angular elevation of the object above the Horizon
Azimuth - CORRECT ANSWER - The angular separation between the object and due
North (increases towards East) (North = 0; East = 90; South = 180; West = 270); Converge on
the Zenith
Celestial Equator - CORRECT ANSWER - The projection of Earth's equator onto the sky
North/South Celestial Pole - CORRECT ANSWER - The point directly above Earth's
North/South Pole
Altitude of Celestial Pole = Latitude of the observer
Constellation - CORRECT ANSWER - A region of the sky with well-defined borders;
names derived from familiar patterns
Declination - CORRECT ANSWER - The angular elevation of the object above the
Celestial Equator
,North Pole = 90 degrees
Right Ascension - CORRECT ANSWER - The angular separation between the object and
the March Equinox line (increases towards East); Converge on the Celestial Poles
Comparing Coordinate Systems - CORRECT ANSWER - The Declination of the Zenith is
equal to the Latitude of the observer
The Declination of a star on the Northern horizon is 90° - Latitude
The Declination of a star on the Southern horizon is Latitude - 90°
Stars with Dec > 90° - Latitude will never set. We call these stars "circumpolar".
Stars with Dec < Latitude - 90° will never rise above the horizon
Any star that passes through the Zenith has Dec = Latitude
Ecliptic - CORRECT ANSWER - The plane of Earth's orbit around the Sun
Tilted 23.5° relative to the Celestial Equator (equivalent to Earth's axial tilt)
Traces the path of the Sun, Moon, and Planets in the night sky
Earth's Axial Tilt - CORRECT ANSWER - Earth's axis is tilted 23.5° relative to its orbital
plane
In June, the Ecliptic is 23.5°above the Celestial Equator (Dec = 23.5°)
In December, the Ecliptic is 23.5° below the Celestial Equator (Dec = -23.5°)
Earth's Axial Tilt and the Seasons - CORRECT ANSWER - June Solstice, or Summer
Solstice, (June 21) is the longest day of the year in the Northern Hemisphere (shortest day in the
Southern Hemisphere).
December Solstice, or Winter Solstice, (December 21) is the shortest day of the year in the
Northern Hemisphere (longest day in the Southern Hemisphere).
Equinox is the day with equal hours of daylight and night - Vernal Equinox on March 21 (varies
by 1-2 days) and Autumnal Equinox on September 21 (varies by 1-2 days).
, The seasons at the Poles and the Equator - CORRECT ANSWER - At the poles, your
horizon is the Celestial Equator. Just like the stars, the Sun will be circumpolar whenever Dec >
0 (North Pole) or Dec < 0 (South Pole).
The Sun doesn't set for 6 months straight! For the other 6 months, the Sun will never rise.
At the Equator, you always experience equal hours of day and night.
Artic Circle - CORRECT ANSWER - Latitude above which the Sun never sets on the
Summer Solstice
Year - CORRECT ANSWER - The time it takes for Earth to return to the same point in its
orbit around the Sun
~365.25 days (hence the need for leap years every 4 years)
Solar Day - CORRECT ANSWER - Earth's rotation period with respect to the Sun (24
hours)
Sidereal Day - CORRECT ANSWER - Earth's rotation period with respect to the stars (23
hours 56 minutes)
Precession - CORRECT ANSWER - The change in orientation of the rotational axis of a
spinning body
Gravitational forces from the Sun and moon cause Earth's axis to precess, changing its
orientation relative to the ecliptic and the celestial sphere
The axis returns to the same orientation every 26,000 years
Inner Planets - CORRECT ANSWER - Planets between the Sun and Earth exhibit
prograde motion along the ecliptic
Mercury and Venus
Inferior Conjunction - between Earth and the Sun
Superior Conjunction - directly opposite of Earth around Sun
ACTUAL Exam Questions and CORRECT
Answers
Horizon - CORRECT ANSWER - A circular boundary between the ground and sky
Zenith - CORRECT ANSWER - A point in the sky directly above the observer
Altitude always = 90
Celestial Meridian - CORRECT ANSWER - An arc connecting the North and South
points on the Horizon and passing through the Zenith
Altitude - CORRECT ANSWER - The angular elevation of the object above the Horizon
Azimuth - CORRECT ANSWER - The angular separation between the object and due
North (increases towards East) (North = 0; East = 90; South = 180; West = 270); Converge on
the Zenith
Celestial Equator - CORRECT ANSWER - The projection of Earth's equator onto the sky
North/South Celestial Pole - CORRECT ANSWER - The point directly above Earth's
North/South Pole
Altitude of Celestial Pole = Latitude of the observer
Constellation - CORRECT ANSWER - A region of the sky with well-defined borders;
names derived from familiar patterns
Declination - CORRECT ANSWER - The angular elevation of the object above the
Celestial Equator
,North Pole = 90 degrees
Right Ascension - CORRECT ANSWER - The angular separation between the object and
the March Equinox line (increases towards East); Converge on the Celestial Poles
Comparing Coordinate Systems - CORRECT ANSWER - The Declination of the Zenith is
equal to the Latitude of the observer
The Declination of a star on the Northern horizon is 90° - Latitude
The Declination of a star on the Southern horizon is Latitude - 90°
Stars with Dec > 90° - Latitude will never set. We call these stars "circumpolar".
Stars with Dec < Latitude - 90° will never rise above the horizon
Any star that passes through the Zenith has Dec = Latitude
Ecliptic - CORRECT ANSWER - The plane of Earth's orbit around the Sun
Tilted 23.5° relative to the Celestial Equator (equivalent to Earth's axial tilt)
Traces the path of the Sun, Moon, and Planets in the night sky
Earth's Axial Tilt - CORRECT ANSWER - Earth's axis is tilted 23.5° relative to its orbital
plane
In June, the Ecliptic is 23.5°above the Celestial Equator (Dec = 23.5°)
In December, the Ecliptic is 23.5° below the Celestial Equator (Dec = -23.5°)
Earth's Axial Tilt and the Seasons - CORRECT ANSWER - June Solstice, or Summer
Solstice, (June 21) is the longest day of the year in the Northern Hemisphere (shortest day in the
Southern Hemisphere).
December Solstice, or Winter Solstice, (December 21) is the shortest day of the year in the
Northern Hemisphere (longest day in the Southern Hemisphere).
Equinox is the day with equal hours of daylight and night - Vernal Equinox on March 21 (varies
by 1-2 days) and Autumnal Equinox on September 21 (varies by 1-2 days).
, The seasons at the Poles and the Equator - CORRECT ANSWER - At the poles, your
horizon is the Celestial Equator. Just like the stars, the Sun will be circumpolar whenever Dec >
0 (North Pole) or Dec < 0 (South Pole).
The Sun doesn't set for 6 months straight! For the other 6 months, the Sun will never rise.
At the Equator, you always experience equal hours of day and night.
Artic Circle - CORRECT ANSWER - Latitude above which the Sun never sets on the
Summer Solstice
Year - CORRECT ANSWER - The time it takes for Earth to return to the same point in its
orbit around the Sun
~365.25 days (hence the need for leap years every 4 years)
Solar Day - CORRECT ANSWER - Earth's rotation period with respect to the Sun (24
hours)
Sidereal Day - CORRECT ANSWER - Earth's rotation period with respect to the stars (23
hours 56 minutes)
Precession - CORRECT ANSWER - The change in orientation of the rotational axis of a
spinning body
Gravitational forces from the Sun and moon cause Earth's axis to precess, changing its
orientation relative to the ecliptic and the celestial sphere
The axis returns to the same orientation every 26,000 years
Inner Planets - CORRECT ANSWER - Planets between the Sun and Earth exhibit
prograde motion along the ecliptic
Mercury and Venus
Inferior Conjunction - between Earth and the Sun
Superior Conjunction - directly opposite of Earth around Sun
