Astronomy Ch. 3 Moon and Phases

If the Moon sets at 7 PM tonight, it will set around... tomorrow night

8 pm, Correct. The moon sets roughly 1 hour later each night, so if it set at 7 PM tonight, it will set around 8 PM tomorrow night

At approximately what time does the Moon rise when it is a third quarter moon?

midnight

At approximately what time does the Moon rise when it is a first quarter moon?

noon

During an eclipse, the shadow of the Earth appears curved as it moves across the Moon because...

The Earth is round, A round Earth casts a round shadow

Why does the Moon appear red during a total eclipse?

The Earth's atmosphere scatters red light onto the moon during a total eclipse, giving it a reddish appearance; If the Earth did not have an atmosphere, the Moon would not appear red during an eclipse.

You are watching a lunar eclipse from some place on the Earth's night side. Will you see the Moon enter the Earth's shadow from the east or from the west?

The Moon moves eastward, so it enters the Earth's shadow from the west

On average, lunar eclipses occur about how often?

2x a year, The Moon and Earth align correctly during the full phase roughly twice a year

At what time does a waning crescent moon set?

3 pm, The waning crescent Moon occurs between Last Quarter and New Moon, so it sets shortly before the Sun sets, around 3 PM.

Explain the difference between sunlight and moonlight

Both originate at the Sun, but sunlight comes directly to us while moonlight is reflected off the Moon on its way to us

What is the phase of the Moon if it is highest in the sky at sunrise?

third quarter

2nd half lunar cycle phases

(just past full, waning gibbous, 3rd quarter, waning crescent, old), will not have risen yet when the sun sets, rising just after sunset (just past full) to just before or at dawn (old moon)

1st half lunar cycle phases

(new, waxing crescent, 1st quarter, waxing gibbous, full), follow the sun by 0 (new) to 12 (full) hours, having risen by sunset, and setting 0-12 hours after the sun sets, at the latest by dawn (just as the moon is at full)

Why is the line of nodes important to the subject of eclipses?

An eclipse can take place only when an extension of the line of nodes passes through the Sun.

The Moon is highest in the sky when it crosses the meridian, halfway between the time of moonrise and the time of moonset. What is the phase of the Moon if it is highest in the sky at midnight?

At midnight the local zenith points into space on the side of Earth away from the Sun. The meridian passes from pole to pole through the zenith, so the Moon, when it crosses this line, is also on the side of Earth away from the Sun: full moon.

A common misconception about the Moon's phases is that they are caused by the Earth's shadow. Explain why this not correct

Earth's shadow only reaches the Moon when it is on the opposite side of the Sun from Earth-when it is full. Thus the shadow cannot account for the phases

A partial eclipse can be seen by fewer people at one time than a full eclipse can

False, All types of lunar eclipses are visible by the entire nighttime half of the Earth

A Waxing Crescent Moon occurs when the Earth casts a circular shadow over most of the Moon

False, Lunar phases occur due to the relative positions of the Earth, Moon & Sun. They are not caused by the Earth casting shadows on the Moon

We see the Moon because it shines by its own light.

False, the moon reflects sunlight

What is the phase of the Moon if it is highest in the sky at sunset?

First quarter

If the Moon is in the first quarter phase today, what phase will it be one week from now?

Full moon, It takes the moon roughly 1 month to go through a complete cycle of phases. Therefore, in one week it will go through about one-fourth of its cycle. One-fourth of the cycle after the first quarter phase is the full moon phase.

Explain why the Moon exhibits phases

Half the Moon is illuminated by the Sun at all times. But, because of the changing positions of Earth, Moon, and Sun, the half of the Moon facing Earth can be entirely illuminated, not illuminated at all, or illuminated to any amount between these two extremes. These are the phases

Why doesn't a lunar eclipse occur at every full moon and a solar eclipse at every new moon?

In order for an eclipse to occur the Sun, Earth, and Moon must be nearly along a straight line. Because the Moon's orbit is tilted slightly with respect to the ecliptic, this does not occur for every full or new moon.

What is the phase of the Moon if it is highest in the sky at noon?

New

What is the line of nodes?

The line of nodes is the line that connects the two points in the Moon's orbit where the orbit crosses the ecliptic.

Which of the following lunar phases is not possible to see at 7 PM?

Third Quarter A person standing on the Earth at 6 PM would see a new Moon setting (during a new Moon phase), a full Moon rising (during a full Moon phase), and any phase in between (in other words, any of the waxing phases). Therefore, the person cannot see any of the waning phases

A Full Moon occurs when the half of the Moon facing Earth is also the half of the Moon illuminated by the Sun

True, Half of the Moon is always illuminated by the Sun. When that half is also facing us, we see a full moon

The intersection of the Earth's orbital plane and the lunar orbital plane is called the line of nodes

True, The line of nodes is the intersection of the two orbital planes

On a particular day, the moon rises in the waxing gibbous phase. What phase is it when it sets?

Waxing gibbous, It takes the moon roughly 1 month to go through a complete cycle of phases. In half of a day, its phase will not change. It will look the same.

first quarter moon

at the midnight position in the sky and sets about 6 hours after the sun sets (moon follows the sun by 6 hours)

Eclipses

occur because the plane of the moon's orbit crosses the plane of the sun's orbit (which is also called the ecliptic) at two points known as the nodes of the moon's orbit, the moon must be at one of the nodes and directly between the sun and the earth in order for a solar eclipse to occur (the moon phase is "new"), and it must be at the the other node and on the opposite side of the earth from the sun in order for a lunar eclipse to occur (the moon is full), I.E. the line connecting the nodes (line of nodes), points exactly along the earth-sun direction at either the new moon or full moon, the shadow of the moon on the earth during a solar eclipse is much smaller than the shadow of the earth in space that covers the moon when it is in lunar eclipse, hence the allignment conditions for lunar eclipses are not as tight as they are for solar eclipses, and they occur much more frequently, around twice a year as opposed to many decades or centuries for any given location on earth

third quarter moon

rises about 6 hours after the sun sets which is the same as rising about 6 hours before sunrise or about midnight (leads sun by 6 hours), high in the sky at the midnight position as the sun rises in the east

full moon

rises as the sun sets and sets 12 hours later at dawn (moon follows or leads sun by 12 hours)

New Moon

sets with the setting sun

At approximately what time does the Moon rise when it is a new moon?

sunrise

At approximately what time does the Moon rise when it is a full moon?

sunset

The name of one of the lunar phases in the Dakota language means "diminishing moon." To which phase would this term most likely apply?

waning crescent

You look at the Moon and notice that more than half of the side facing the Earth is illuminated, and that it is illuminated on the left-hand side. Because of this, you know that it is a...

waning gibbous moon, A gibbous phase occurs when more than half of the moon is illuminated. If the left half of the moon is illuminated, then it is waning. Therefore, it is a waning gibbous moon.

You are meeting a friend for a late dinner at 9 PM. While waiting for him, you notice the Moon near the western horizon. What phase is it?

waxing crescent, If the Moon is near the western horizon, then it must be setting. If it is setting at 9 PM, then it is setting shortly after the Sun set, and therefore must be a phase close to the New Moon (which sets at the same time as the Sun). The waxing crescent phase sets shortly after the Sun sets