Quick Review Flashcards - Click to flip and test your knowledge!
Question
What is the primary source of the Moon's light?
Answer
The Moon reflects sunlight that falls on it.
Question
What is the geometric shape of the Moon?
Answer
The Moon is spherical.
Question
Why is the Moon sometimes visible during the day?
Answer
It reflects enough sunlight to be seen even when the Sun is up.
Question
What term describes the changing shapes of the bright portion of the Moon as seen from Earth?
Answer
Phases of the Moon.
Question
The two-week period during which the bright portion of the Moon decreases is called the _____ period.
Answer
Waning
Question
What is the Indian name for the waning period of the Moon?
Answer
Krishna Paksha.
Question
The two-week period during which the bright portion of the Moon increases is called the _____ period.
Answer
Waxing
Question
What is the Indian name for the waxing period of the Moon?
Answer
Shukla Paksha.
Question
What is the specific name for the day the Moon appears as a full bright circle?
Answer
Full Moon day (or Purnima).
Question
What is the specific name for the day the Moon is not visible from Earth?
Answer
New Moon day (or Amavasya).
Question
Approximately how long does the cycle from one full Moon to the next take?
Answer
About a month (specifically $29.5$ days).
Question
On a full Moon day, what is the position of the Moon relative to the Sun?
Answer
The Moon is nearly opposite the Sun.
Question
Where is the full Moon located in the sky when the Sun rises in the East?
Answer
The Moon is almost setting in the West.
Question
As the bright part of the Moon decreases after a full Moon, how does its position relative to the Sun change?
Answer
The Moon appears to move closer to the Sun in the sky.
Question
At what time of day is a waxing Moon easiest to spot?
Answer
At sunset.
Question
At what time of day is a waning Moon easiest to spot?
Answer
At sunrise.
Question
Why do the Moon and Sun rise and set at different times?
Answer
The Moon's position in the sky shifts daily due to its orbit.
Question
How many minutes later does the Moon rise each day on average?
Answer
About $50$ minutes.
Question
Why does the Moon appear to rise $50$ minutes later each day?
Answer
The Earth must rotate more to face the Moon because the Moon has moved ahead in its orbit.
Question
How much of the Moon is illuminated by the Sun at any given time?
Answer
Exactly one half.
Question
Why is the entire illuminated portion of the Moon not always visible from Earth?
Answer
The illuminated half does not always face the Earth fully.
Question
Which part of the Moon faces the Earth during a new Moon?
Answer
The non-illuminated portion.
Question
In Activity 11.2 (the ball and stick model), what does the student's head represent?
Answer
The Earth.
Question
In Activity 11.2 (the ball and stick model), what does the ball represent?
Answer
The Moon.
Question
In Activity 11.2 (the ball and stick model), what does the torchlight or lamp represent?
Answer
The Sun.
Question
When a ball is held towards a light source to model the Moon, which phase is being represented?
Answer
The new Moon phase.
Question
When a ball is held opposite a light source to model the Moon, which phase is being represented?
Answer
The full Moon phase.
Question
What is the name of the phase when more than half of the illuminated portion of the Moon is visible?
Answer
Gibbous phase.
Question
What is the name of the phase when less than half of the illuminated portion of the Moon is visible?
Answer
Crescent phase.
Question
What is the shape of the line separating the illuminated and non-illuminated portions of the Moon as seen from Earth?
Answer
A curved line.
Question
Why do people in different parts of the Earth see nearly the same Moon phase on the same day?
Answer
Earth's rotation period is much shorter than the Moon's revolution period.
Question
At what phase does the Moon appear closest to the Sun in the sky?
Answer
New Moon.
Question
At what phase does the Moon appear farthest from the Sun in the sky?
Answer
Full Moon.
Question
Are Moon phases caused by the Earth's shadow falling on the Moon?
Answer
No, they are caused by the relative orientation of the Sun, Moon, and Earth.
Question
What celestial event is caused by the Earth's shadow falling on the Moon?
Answer
A lunar eclipse.
Question
During which phase can a lunar eclipse only occur?
Answer
A full Moon day.
Question
During which phase can a solar eclipse only occur?
Answer
A new Moon day.
Question
Why do eclipses not occur every single month?
Answer
The Moon's orbit is slightly tilted with respect to the Earth's orbit around the Sun.
Question
Which natural cycle is the foundation for the unit of a 'day'?
Answer
The rotation of the Earth around its own axis.
Question
What is the definition of a 'mean solar day'?
Answer
The average time the Sun takes to return to its highest position in the sky.
Question
How long is a mean solar day?
Answer
$24$ hours.
Question
How can the highest position of the Sun in the sky be identified using shadows?
Answer
It is the moment when the shadow cast by an object is shortest.
Question
Which natural cycle is the primary basis for the unit of a 'month'?
Answer
The cycle of the phases of the Moon.
Question
Which natural cycle defines a 'solar year'?
Answer
The Earth's revolution around the Sun (one cycle of seasons).
Question
Approximately how many days does it take for the Earth to complete one revolution around the Sun?
Answer
$365 \frac{1}{4}$ days.
Question
How many cycles of Moon phases typically occur within one cycle of seasons?
Answer
Nearly $12$ lunar months.
Question
How many days are in a standard lunar year consisting of $12$ lunar months?
Answer
$354$ days.
Question
What is the difference in length between a solar year and a lunar year?
Answer
Nearly $11$ days.
Question
Why do seasons not remain synchronised with the same months in a purely lunar calendar?
Answer
The lunar year is shorter than the solar year by about $11$ days.
Question
How often must time be added to a lunar calendar to re-synchronise it with the solar year?
Answer
Every $2$--$3$ years.
Question
What was the shortest unit used to measure time in ancient lunar calendars?
Answer
The day.
Question
What happens to the shadow of a vertical stick as the Sun reaches its highest point in the sky?
Answer
The shadow becomes shortest.
Question
At what Moon phase is the Moon located overhead at sunrise?
Answer
When the bright portion has decreased to a half circle.
Question
Which city hosts the International Kite Festival mentioned in the text?
Answer
Ahmedabad.
Question
What is the name of the kite festival celebrated during Makar Sankranti?
Answer
Patang Mahotsav.
Question
What is the duration of one waxing or waning cycle?
Answer
About one week to reach half and another week to reach full/new.
Question
How does the size of the bright portion of the Moon change during the waxing period?
Answer
It increases from a new Moon to a full Moon.
Question
How does the separation between the Moon and Sun in the sky change during the waning period?
Answer
The Moon appears to move closer to the Sun.