AY 101 002 CH 2 HW
Start at the beginning of the Moon Orbit video, which shows the Sun and part of Earth's orbit. If we wanted to show the Moon's orbit on the scale of this starting frame, we would need to draw a circle that __________.
is smaller than one of the green dashes that show Earth's orbit
If the Sun rises precisely due east:
it must be the day of either the spring or fall equinox.
in words, kg/m ^3 means
kilograms per cubic meters
The North Celestial Pole is 35∘ above your northern horizon. This tells you that you are at:
latitude 35∘ N
If the date is April 21, what zodiac constellation will be visible on your meridian at midnight?
libra
Two stars that are in the same constellation:
may actually be very far away from each other.
in words, m/s means
meters per second
in words, m/s ^2 means
meters per second squared
The diagram exaggerates the sizes of Earth and the Sun relative to the orbit. If Earth were correctly scaled relative to the orbit in the figure, how big would it be?
microscopic
A total solar eclipse can only happen during what lunar phase?
new
If you wanted to document the apparent retrograde motion of Mars, you would need to measure and record Mars's _____________________ over a period of __________________.
position among the constellations, several months
Look again at the Causes of Lunar Phases video. At what position(s) in the Moon's orbit would we see exactly half of the Moon's daylight face and exactly half of its night face?
at the two points at the top and bottom
Consider a time when Mars is in the middle of one of its periods of apparent retrograde motion. During this time, Mars appears ___________ in our night sky and crosses the meridian around _________.
brightest, midnight
2 years x _____________ = 24 months
12 months/1 year
Recall that 1 foot = 12 inches. Therefore, 1 square foot = _____ square inches.
144
Part complete How many arcminutes are in a full circle?
2.16 × 10 ^4 arcminutes
Which of the four labeled points (A through D) represents the day with the most hours of daylight for the Northern Hemisphere?
B
Which of the four labeled points represents the beginning of spring for the Southern Hemisphere?
C
Which of the four labeled points represents the day with the most hours of daylight for the Southern Hemisphere?
D
in words, m ^3 means
cubic meters
At most times, Mars appears to move ______________ relative to the stars. The exceptions are during its periods of apparent retrograde motion, when Mars appears to move ______________ relative to the stars.
eastward, westward
As seen from Earth, the Sun appears to follow the annual path that we call the __________ around the celestial sphere.
ecliptic
What are your latitude and longitude?
The latitude in Boulder is 40∘N and the longitude is about 105∘W.
Where does the north (or south) celestial pole appear in your sky?
The north celestial pole appears in Boulder 's sky at an altitude of 40 ∘ in the direction due north.
A viewed from Earth, in which zodiac constellation does the Sun appear to be located on April 21?
aries
Watch the Causes of Lunar Phases video. To understand phases of the Moon, you must imagine the view from Earth looking out to the Moon as it orbits. At what position(s) in its orbit would we see all of the Moon's daylight side and none of its night side?
at the point on the far left
Play the Moon Orbit video through to where you see the Moon orbiting Earth at correctly scaled sizes. Notice that Earth's daylight side (white) is on the right in this view, and its night side (gray) is on the left. Where along its orbit would the Moon also have its daylight side on the right and its night side on the left?
everywhere along its orbit
Although the Causes of Lunar Phases video is very useful for learning about phases of the Moon, it is inaccurate in some ways. Which of the following correctly identify inaccuracies with this video? Check all that apply. - Earth is too big compared to the Moon's orbit. - The astronaut is too big compared to the Moon. - The Moon is too big compared to its orbit. - The Moon is too small compared to Earth. - The Moon is too big compared to Earth. - Earth is rotating much too fast relative to the speed of the Moon's orbit in the video.
- Earth is too big compared to the Moon's orbit. - The astronaut is too big compared to the Moon. - The Moon is too big compared to its orbit. - The Moon is too big compared to Earth.
Which of the following statements about phases of the Moon are true? Select all that apply. - at new moon, we see only the "night" side of the Moon - at new moon, the half of the Moon facing the Sun is fully illuminated - at new moon, the Moon's entire surface is engulfed in darkness - the time between new moon and full moon is about two weeks - if it is full moon, the Moon will rise around sunset - the time between first-quarter moon and third-quarter moon is about a month - if it's new moon, the Moon will rise in the middle of the day
- at new moon, we see only the "night" side of the Moon - at new moon, the half of the Moon facing the Sun is fully illuminated - the time between new moon and full moon is about two weeks - if it is full moon, the Moon will rise around sunset
600 centimeters x _____________ = 6 meters
1 meter/100 centimeters
24 months x ____________ = 2 years
1 year/12 months
How many arcseconds are in a full circle?
1.296 × 10 ^6 arcseconds
6 meters x ______________ = 600 centimeters
100 centimeters/1 meter
Recall that 1 centimeter = 10 millimeters. Therefore, 1 cubic centimeter = _____ cubic millimeters.
1000
A large boulder has a volume of 1000 cubic meters and a mass of 3,200,000 kilograms. What is the density of the boulder, in grams per cubic centimeter?
3.2 g/cm ^3
in words, 4 boxes x 5 kg/box means
4 boxes of 5 kilograms per box
The surface area of a small moon is 50,000 square kilometers, which is equivalent to _____ square meters. (Recall that 1 kilometer = 1000 meters.)
50,000×1000 ^2
When we see Saturn going through a period of apparent retrograde motion, it means
Earth is passing Saturn in its orbit, with both planets on the same side of the Sun.
Part complete What is really happening in space during the periods when we see Mars going through apparent retrograde motion?
Earth is passing by Mars in its orbit around the Sun.
The Sun rises and sets each day because
Earth rotates once each day
Which of the following planets has essentially no seasons at all?
Jupiter (axis tilt = 3.1°)
Based on what you have learned from your rankings in Parts A and B, which of the following planets would you expect to have seasons most like Earth's?
Mars (axis tilt = 25.2°)
The Sun-centered system pictured in the lower window of the video offers a simple explanation for observations of apparent retrograde motion. Should these facts alone have been enough to convince the ancient Greeks that Earth really does go around the Sun?
No, because the Greeks had an Earth-centered model that also accounted for apparent retrograde motion.
Is Polaris a circumpolar star in Boulder 's sky? Choose the correct explanation.
Polaris is circumpolar because it never rises or sets in Boulder 's sky.
As you play the Moon Orbit video, notice how the arrows representing the Sun's rays are at first spread apart but become parallel as the video zooms in on the Moon's orbit. Why do the Sun's rays become parallel at the end of the video?
The Sun is so far away compared to the size of the Moon's orbit that all the rays reaching the orbit come from essentially the same direction.
You've now seen that Earth's varying distance cannot be the cause of our seasons. So what is the cause of the seasons?
The tilt of Earth's axis causes different portions of the Earth to receive more or less direct sunlight at different times of year.
Based on what you have learned from your rankings in Parts A and B, which statement best describes how variation in the Earth-Sun distance affects the seasons?
The variation in Earth-Sun distance over the course of each year has virtually no effect on the seasons.
Which of the following planets should have the most extreme seasons?
Uranus (axis tilt = 97.9°)
Look again at the Causes of Lunar Phases video. As the Moon orbits, notice how the astronaut's head always points toward Earth. What do we see from Earth that occurs for the same reason? (Be sure you are viewing the first portion of the video, with the rotating Moon, not the hypothetical, non-rotating view, shown afterward.)
We always see the same face of the Moon
in words, m ^2 means
square meteres
If the date is April 21, what zodiac constellation will you see setting in the west shortly after sunset?
taurus
If there is going to be a total lunar eclipse tonight, then you know that:
the Moon's phase is full.
The fact that we always see the same face of the Moon tells us that
the Moon's rotation period is the same as its orbital period.
In winter, Earth's axis points toward the star Polaris. In spring:
the axis also points toward Polaris.
Given that Earth's actual distance from the Sun varies less than 3% over the course of a year, why does the diagram look so elliptical?
the elliptical shape is an effect of perspective, since the diagram shows an almost edge-on view of a nearly circular orbit.
A week after full moon, the Moon's phase is:
third quarter.
Beijing and Philadelphia have about the same latitude but very different longitudes. Therefore, tonight's night sky in these two places:
will look about the same.
When it is summer in Australia, the season in the United States is
winter
The Moon's angular size is about 12∘. What is this in arcseconds?
θMoon = 1800 arcseconds
The Moon's angular size is about 12∘. What is this in arcminutes?
θMoon = 30.0 arcminutes
