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Astro 101 (Midterm) Questions and Correct
Answers
At noon, which phase could the observer see?
Waning Gibbous
Full
Waxing Crescent Ans: Waxing Crescent
(At noon the Moon is only visible if it is on the sunny side of the
Earth, the only phases possible in this orientation are New,
Crescent, and (barely) Quarter.)
When could you see a full Moon?
Noon, sunset, or midnight.
Sunset, midnight, or sunrise.
Midnight only.
Anytime. Ans: Sunset, midnight, or sunrise.
(A Full Moon is only below the horizon in the middle of the day.)
When the Moon is seen as full in Seattle, what is the phase of the
Moon as viewed twelve hours later from the opposite side of the
Earth?
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New
Full
Third Quarter Ans: Full
(Moon phases are the same for the whole Earth.)
If you were on the Moon, could you see the Earth go through
phases?
Yes
No Ans: Yes
(Phases just depend on orientation, so the Earth has phases as well
when viewed different sides.)
Which world could appear in a crescent phase, as viewed from
Jupiter?
Mars
Saturn
Both of these worlds
Neither of these worlds Ans: Mars
When the Earth is to the left of the Sun in the orbit view,
the stars an observer at the UW can see above their head at night
are:
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to the left of the Sun and Earth.
toward the bottom of this picture.
toward the top of this picture.
to the right of the Sun and Earth. Ans: to the left of the Sun and
Earth.
Six months later, when the Earth is to the right of the Sun, the
stars an observer at the UW can see at night are:
You can use the simulator to answer this question by moving the
Earth until the calendar at the bottom indicates six months have
past.
to the right of the Sun and Earth.
below the Sun and Earth.
to the left of the Sun and Earth.
above the Sun and Earth. Ans: to the right of the Sun and Earth.
If, on the same date, the observer was instead near the South Pole,
which season would they be in?
Winter
Spring
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Fall
Summer Ans: Summer
In Seattle (which is at about +48 degrees latitude) what is the
greatest altitude the Sun gets to during a summer day? During a
winter day?
90 degrees (straight up) in the summer, and 0 degrees in the
winter.
80 degrees in summer, down to about 32 degrees in winter.
65 degrees in summer, down to 20 degrees in winter.
90 degrees (straight up) in both the summer and the winter, it's
just not up for as long in the winter Ans: 65 degrees in summer,
down to 20 degrees in winter.
Rotate the Earth (either by dragging, or use the start animation
button) so the observer is in the middle of the shadowed side of
the Earth. What time is it for the observer?
Sunrise
Noon
Sunset
Midnight Ans: Midnight
Now you know how to do that, hide the Horizon Diagram for now.
Use the start animation button to spin the Earth. Where in this
simulation is the observer at sunset?
© 2025 All rights reserved
Astro 101 (Midterm) Questions and Correct
Answers
At noon, which phase could the observer see?
Waning Gibbous
Full
Waxing Crescent Ans: Waxing Crescent
(At noon the Moon is only visible if it is on the sunny side of the
Earth, the only phases possible in this orientation are New,
Crescent, and (barely) Quarter.)
When could you see a full Moon?
Noon, sunset, or midnight.
Sunset, midnight, or sunrise.
Midnight only.
Anytime. Ans: Sunset, midnight, or sunrise.
(A Full Moon is only below the horizon in the middle of the day.)
When the Moon is seen as full in Seattle, what is the phase of the
Moon as viewed twelve hours later from the opposite side of the
Earth?
© 2025 All rights reserved
, 2 | Page
New
Full
Third Quarter Ans: Full
(Moon phases are the same for the whole Earth.)
If you were on the Moon, could you see the Earth go through
phases?
Yes
No Ans: Yes
(Phases just depend on orientation, so the Earth has phases as well
when viewed different sides.)
Which world could appear in a crescent phase, as viewed from
Jupiter?
Mars
Saturn
Both of these worlds
Neither of these worlds Ans: Mars
When the Earth is to the left of the Sun in the orbit view,
the stars an observer at the UW can see above their head at night
are:
© 2025 All rights reserved
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to the left of the Sun and Earth.
toward the bottom of this picture.
toward the top of this picture.
to the right of the Sun and Earth. Ans: to the left of the Sun and
Earth.
Six months later, when the Earth is to the right of the Sun, the
stars an observer at the UW can see at night are:
You can use the simulator to answer this question by moving the
Earth until the calendar at the bottom indicates six months have
past.
to the right of the Sun and Earth.
below the Sun and Earth.
to the left of the Sun and Earth.
above the Sun and Earth. Ans: to the right of the Sun and Earth.
If, on the same date, the observer was instead near the South Pole,
which season would they be in?
Winter
Spring
© 2025 All rights reserved
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Fall
Summer Ans: Summer
In Seattle (which is at about +48 degrees latitude) what is the
greatest altitude the Sun gets to during a summer day? During a
winter day?
90 degrees (straight up) in the summer, and 0 degrees in the
winter.
80 degrees in summer, down to about 32 degrees in winter.
65 degrees in summer, down to 20 degrees in winter.
90 degrees (straight up) in both the summer and the winter, it's
just not up for as long in the winter Ans: 65 degrees in summer,
down to 20 degrees in winter.
Rotate the Earth (either by dragging, or use the start animation
button) so the observer is in the middle of the shadowed side of
the Earth. What time is it for the observer?
Sunrise
Noon
Sunset
Midnight Ans: Midnight
Now you know how to do that, hide the Horizon Diagram for now.
Use the start animation button to spin the Earth. Where in this
simulation is the observer at sunset?
© 2025 All rights reserved
