MOON ch3 Astro 102
You face the Moon from a position in the northern hemisphere and find that the right half is illuminated and the left half is dark. if you watch the Moon over the next several nights you will observe that the boundary separating the light and dark portions of the Moon's visible surface
moves to the left so that more of the Moon's surface is illuminated.
Which of the following lunar phases is never seen above the horizon at 7 PM?
not see: third quarter Correct. 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 an hour later at 7 PM the person could see all of the waxing phases (except the new Moon) and the first waning phase - waning gibbous. All the other waning phases are never seen at 7 PM.
In order for a lunar eclipse to occur the lunar phase must be full and
* the Moon must be near the line of nodes in its orbit. The line of nodes is where the Earth and Moon line up in the same plane. A lunar eclipse requires two conditions to be met: 1) the Moon must be in the full phase, and 2) the Earth and the Moon must lie in the same plane. This is why there are many more full Moons each year than there are lunar eclipses! These two conditions are met roughly twice a year about 6 months apart.
At what time does a waning crescent Moon set?
*3PM Incorrect. The waning crescent Moon occurs between Last Quarter and New Moon, so it sets shortly before the Sun sets, around 3 PM
You are meeting a friend for a late dinner at 9 PM. While waiting for him, you notice the Moon setting on 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.
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 Correct. 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.
Roughly how long does it take the Moon to complete one full cycle of phases?
1 month / 4 weeks Correct. The Moon takes roughly 4 weeks, or about 1 month to go from New Moon to New Moon again.
_____ is the period during a total lunar eclipse when the Moon is completely within the Earth's umbra.
A: Totality
A solar eclipse that occurs when the Moon is distant and its umbra does not touch the Earth's surface is called a(n)
Annular Eclipse
Occasionally we see an annular solar eclipse, with an annulus (ring) of the Sun surrounding the Moon. How do the conditions that produce such an eclipse differ from the conditions that produce a total solar eclipse during which the Moon is seen to just cover the Sun?
Any one of the conditions described in the previous three answers will produce an annular eclipse
####If you were to look at the Moon during a penumbral lunar eclipse, what would you see? A: The entire Moon would be slightly fainter than usual but still quite bright.
Aristarchus of Samos was able to measure the relative distances to the Sun and Moon by noting that when the Sun was overhead, a _____ moon was 87° away from the Sun. A: Quarter MOON
During which lunar phase does a lunar eclipse occur?
FULL MOON A lunar eclipse occurs when the Moon moves into the Earth's shadow. This occurs when the Earth is directly between the Sun and the Moon; this is the full phase of the lunar cycle. Normally, the side of the Moon facing the Earth would be completely illuminated during the full phase; an eclipse occurs when the Moon and Earth are aligned such that the Earth casts a shadow on the Moon
If the Moon is in the first quarter phase today, what phase will it be one week from now?
FULL MOON Correct. 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.
If astronauts landed on the Moon near the center of the visible surface at full moon, how many Earth days would pass before the astronauts would experience darkness on the Moon? A: ONE WEEK
If you were to look at the Moon during a penumbral lunar eclipse, what would you see? A:The entire Moon would be slightly fainter than usual but still quite bright.
The terminator line separating the illuminated and dark portions of the Moon's surface, when viewed from Earth's northern hemisphere, gradually moves to the ____.
Left
A first-quarter Moon will cross the ____ at approximately 6:00 P.M.
Meridian
The phase of the Moon that immediately follows waxing gibbous is? A: FULL MOON
More than ____ of the total surface of the Moon is illuminated by the Sun when it is at gibbous phase. A: HALF (50%)
At sunrise, the Moon has not yet risen.
The Moon is a little farther over in its orbit, so it is not yet viewable at sunrise. It is still below the eastern horizon for the observer. It will take about an hour before the Earth has rotated enough so that the Moon will be on the eastern horizon. As you can see, from day to day, due to the Moon's motion around the Earth while the Earth rotates, it will appear to rise roughly 1 hour later each day.
Which of the following statements correctly describes the reason for the phases that we see on the Moon?
The Moon orbits around the Earth.
Look at the first 5 phases of the Moon, from New Moon to Full Moon. How does the appearance of the Moon change from one phase to the next?
The bright portion of the Moon is increasing. Correct. The Moon is becoming a little fuller each night, or the portion of the Moon which we can see becomes more illuminated.
Roughly what percent of the Earth can see a lunar eclipse at one time? 50%
The entire nighttime half of the Earth can see a lunar eclipse - whether full, partial, or penumbral - at one time. This is because lunar eclipses occur during the full phase when the Earth is between the Moon and the Sun. Thus, any place on Earth where the Sun is below the horizon - i.e., the whole nighttime side - could see the eclipse. Because the Moon is so much smaller than the Earth's shadow, all latitudes on the nighttime side of the Earth can see the eclipse simultaneously.
LINE OF NODES
The intersection of the plane of the Moon's orbit and the plane of the Earth's orbit is called the line of nodes.
The waxing gibbous Moon occurs during the seven days after A:1st Quarter
The line of _____ is where the plane of the Moon's orbit intersects the place of the ecliptic. A: NODES
The phases that we see on the Moon occur because the Moon _____ around the Earth. A: ORBITS
The saros cycle on Earth is 6585⅓ days. How many saros cycles must you wait for a total solar eclipse to be repeated at your location? A: THREE
There are two crescent phases, a waxing crescent and a waning crescent. If you saw the Moon in the sky how could you tell which crescent you are observing?
The waxing crescent is lit on the right; the waning crescent is lit on the left. Correct. The waxing moons are illuminated on the right side, and the waning moons are illuminated on the left side, but only if you live in the Northern Hemisphere! It turns out that people living in the Southern Hemisphere observe the Moon from a different perspective, and so during the waxing phases the illumination occurs on the left side of the Moon, while the right side is illuminated during the waning phases.
On a particular day, the Moon rises in the waxing gibbous phase. What phase is it when it sets?
WAXING GIBBOUS Correct. 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.
Totality is the period during a total lunar eclipse when the Moon is completely within the Earth's umbra. Does this time vary from one total lunar eclipse to another and if so, why?
Yes. The time varies significantly because the Moon does not always pass through the widest part of the Earth's umbra.
.Which way will the "horns," or sharp ends of the crescent, of the Moon point in the sky when the Moon is above the eastern horizon at sunrise at a phase 3 days before new moon? A: away from the Sun, westward
You are watching a total lunar eclipse from Wellington, New Zealand. I'm in Sydney, Australia, 2200 km away from Wellington, and the Moon is above my horizon. What do I see when I look at the Moon? A: Total Lunar Eclipse
The "dark side" of the Moon refers to
a misconception. No side of the Moon is always dark.
A full lunar "day" will last for _____ days, from midday to midday, at any location on the Moon's equator.
29.5 days
How much of the Moon's surface is illuminated by the Sun?
50 % the Sun, the half facing the Sun. In fact, half of the Moon is always illuminated by the Sun, and half of the Moon always faces the Earth, but these two halves don't always coincide. During the Full Moon phase as shown above, they do. The half facing Earth is the half which is illuminated.
If the Moon sets at 7 PM tonight, it will set around __________ tomorrow night.
8pm 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.
When would a waning gibbous Moon rise?
9 PM Correct. The waning gibbous phase occurs between the Full Moon and the Third Quarter phases, and so rises between 6 PM and midnight. If the waning gibbous phase rises around 9 PM, then it sets around 9 AM.
The Moon turn on its axis _____ time(s) during each orbit it makes around the Earth A: ONE
A _____ is the time from one alignment of the Sun, the Moon, and the line of nodes to the next identical alignment. A: SAROS
A saros is the time from A:one alignment of the Sun, the Moon, and the line of nodes to the next identical alignment.
A _____ month is the time over which the Moon completes one orbit around the Earth relative to the distant stars. A: SIDEREAL
But why can you see the Moon? In the second view you can observe what happens without the sun.
No, the Moon shines by reflected sunlight. The only reason we see the Moon is because light from the Sun reflects off it. Like It
A _____ is the time from one alignment of the Sun, the Moon, and the line of nodes to the next identical alignment.
Saros
You face the Moon from a position in the northern hemisphere and find that the right half is illuminated and the left half is dark. if you watch the Moon over the next several nights you will observe that the boundary separating the light and dark portions of the Moon's visible surface A: Moves to the left, so that more of the moon is illuminated
The Moon completes an orbit around the Earth each synodic month. Why don't we see a solar eclipse each calendar month? A:For a solar eclipse to occur, the Moon must be near the plane of the ecliptic as it passes between the Earth and the Sun, and that does not happen every month.
The Moon doesn't disappear completely during a total eclipse. Instead, when it moves completely into the umbra of the Earth's shadow, the Moon turns distinctly reddish. Why does this happen?
the Earth's atmosphere bends or refracts the sun's rays into the Earth's shadow. The Earth's atmosphere bends or refracts the Sun's rays, redirecting them towards the Moon, then you've got it! Why does the bending of the Sun's rays turn the Moon red instead of white? The particles that make up Earth's atmosphere are about the size of the wavelengths of blue light, so they absorb blue light efficiently. These particles then re-emit the absorbed light randomly, so that the blue wavelengths no longer move uniformly forward. This process is called scattering. Longer wavelengths of light (like red light) pass through Earth?s atmosphere without being absorbed, so red light is not scattered. Instead, as the red light enters the Earth's atmosphere it bends or is refracted. Refraction occurs when light passes from one medium into another (here, when light moves from outer space into Earth's atmosphere), and the light changes direction. Earth's atmosphere bends the rays of red light such that they illuminate the Moon, making it appear red. This is shown dramatically below. Notice that the shadow of the Earth appears curved as it crosses the lunar surface. This happens because the Earth itself if round, and thus casts a circular shadow on the Moon.
A full moon occurs when:
the half of the Moon facing Earth is also the half of the Moon illuminated by the Sun.
A waxing crescent moon occurs:
when the Sun is at its eastern elongation and is rising.
