Module 2 Flashcards
1
Q
What term did R. Buckminster Fuller use to describe Earth?
A
Spaceship Earth
This term emphasizes the idea that Earth is a vessel moving through space.
2
Q
What are the two basic motions of Earth?
A
- Daily rotation (spin)
- Yearly orbit (revolution) around the Sun
3
Q
Which direction does Earth rotate when viewed from above the North Pole?
A
Counterclockwise
4
Q
What is the speed of Earth’s rotation at the equator?
A
More than 1000 kilometers per hour (600 miles per hour)
5
Q
What is an astronomical unit (AU)?
A
About 150 million kilometers
6
Q
What is Earth’s average orbital speed around the Sun?
A
In excess of 100,000 kilometers per hour (60,000 miles per hour)
7
Q
What is the ecliptic plane?
A
The flat plane defined by Earth’s orbital path around the Sun
8
Q
By how much is Earth’s axis tilted from a line perpendicular to the ecliptic plane?
A
23 degrees
9
Q
What star does Earth’s axis point toward?
A
Polaris (the North Star)
10
Q
What is the speed of the Sun relative to nearby stars?
A
About 70,000 kilometers per hour (40,000 miles per hour)
11
Q
Why do stars appear to remain fixed in the sky despite their motion?
A
Their vast distances from us
12
Q
What is the estimated orbital speed of our solar system around the center of the Milky Way Galaxy?
A
Close to 800,000 kilometers (500,000 miles) per hour
13
Q
How long does it take for our solar system to complete one orbit of the Milky Way Galaxy?
A
About 230 million years
14
Q
What is dark matter?
A
Invisible matter that makes up most of the mass of galaxies but does not emit light
15
Q
What is dark energy?
A
The mysterious force causing the accelerated expansion of the universe
16
Q
What two discoveries did Edwin Hubble make about galaxies?
A
- Virtually every galaxy outside the Local Group is moving away from us
- The more distant the galaxy, the faster it appears to be racing away
17
Q
What analogy is used to explain the expanding universe?
A
The raisin cake analogy
18
Q
In the raisin cake analogy, what does the distance between raisins represent?
A
The distance between galaxies
19
Q
How does the speed of galaxies relate to their distance from us?
A
More distant galaxies move away from us faster
20
Q
What happens to the universe as it expands?
A
Space itself is growing between galaxies
21
Q
What is the implication of Hubble’s discovery for the age of the universe?
A
The faster the rate of expansion, the younger the universe must be
22
Q
Fill in the blank: Earth completes one orbit around the Sun each _______.
A
Year
23
Q
True or False: The rotation of the Earth affects the fixed patterns of constellations in the night sky.
A
False
24
Q
What is the circumference of Earth at the equator?
A
40,074 kilometers
25
What does the expansion of the universe resemble in the raisin cake analogy?
The expanding dough between the raisins represents space growing between galaxies
## Footnote
This analogy illustrates how galaxies move away from each other as the universe expands.
26
How do we measure the age of the universe?
By precisely measuring the expansion rate
## Footnote
The faster the rate of expansion, the younger the universe must be.
27
What is one important distinction between the universe and a raisin cake?
The universe has no center or edges
## Footnote
Unlike a cake, which has a defined center and edges, the universe appears homogeneous from any point.
28
What phenomenon do astronomers use to measure the speeds of galaxies?
Doppler shifts
## Footnote
This method involves spreading the light of galaxies into spectra to observe shifts in frequency.
29
What speeds do we experience as we move through the universe?
Various speeds including:
* 1000 kilometers per hour (Earth's rotation)
* 100,000 kilometers per hour (Earth's orbit around the Sun)
* 70,000 kilometers per hour (solar system's motion among stars)
* 800,000 kilometers per hour (orbiting the center of the Milky Way)
## Footnote
These speeds illustrate our dynamic movement through space.
30
What major revolution in astronomy did Copernicus initiate?
The Copernican revolution
## Footnote
This revolution established that the Earth is not the center of the universe but orbits the Sun.
31
Who were the key figures that contributed evidence to the Copernican idea?
Tycho Brahe, Johannes Kepler, and Galileo
## Footnote
Their work supported the heliocentric model proposed by Copernicus.
32
What was the consequence of Galileo's claims about the heliocentric model?
He was put under house arrest by the Vatican
## Footnote
This event sparked significant debate in religious and scientific circles.
33
What is the celestial sphere?
An illusion used for mapping the sky as seen from Earth
## Footnote
It helps visualize the positions of stars and constellations despite our lack of depth perception.
34
What are the two special points on the celestial sphere?
North celestial pole and south celestial pole
## Footnote
These points correspond to the Earth's poles projected into space.
35
What is the celestial equator?
A projection of Earth's equator into space
## Footnote
It circles the celestial sphere and divides it into northern and southern hemispheres.
36
What comprises the Milky Way as seen from Earth?
A band of light that circles the celestial sphere
## Footnote
This band represents our galaxy's disk of stars as viewed from our position within it.
37
What does the term 'local sky' refer to?
The sky as seen from a specific location on Earth
## Footnote
It appears as a dome or hemisphere due to the ground blocking half of the celestial sphere.
38
What are the key reference points in the local sky?
Horizon, zenith, and meridian
## Footnote
These points help define the position of celestial objects from a specific location.
39
What is angular size?
The angle an object appears to span in your field of view
## Footnote
It helps describe the apparent size of celestial objects without knowing their actual distance.
40
Fill in the blank: The Milky Way Galaxy is shaped like a _______.
thin pancake
## Footnote
This structure explains our view of the galaxy from Earth.
41
True or False: All stars in a constellation are at the same distance from Earth.
False
## Footnote
Stars in a constellation may be at very different distances, creating an illusion of proximity.
42
What does the ecliptic represent?
The path the Sun follows as it appears to circle the celestial sphere
## Footnote
It crosses the celestial equator at a 23° angle due to Earth's axial tilt.
43
What is the significance of the Copernican revolution in human history?
It redefined humanity's place in the universe
## Footnote
This shift influenced scientific, philosophical, and cultural perspectives.
44
What technological advancements have impacted modern astronomy?
Space travel and computer technology
## Footnote
These advancements have led to the exploration of the solar system and enhanced telescope capabilities.
45
What is the angular size of an object?
The angle it appears to span in your field of view.
## Footnote
For example, the angular sizes of the Sun and Moon are each about 0.5°.
46
How does angular size relate to distance?
Angular size does not tell us an object's true size because it depends on distance.
## Footnote
The Sun is about 400 times larger than the Moon but has the same angular size due to being 400 times farther away.
47
What do we measure when looking at objects in the sky?
We measure angular sizes or angular distances rather than actual sizes or distances.
48
What is the angular distance between two objects?
The angle that appears to separate them in the sky.
49
How is each degree subdivided?
Each degree is subdivided into 60 arcminutes, and each arcminute into 60 arcseconds.
50
What is the small-angle formula?
angular size = (physical size / (2 * π * distance)) * 360°.
51
What is the angular separation of two headlights 1.5 meters apart when the car is 500 meters away?
0.17° or about 10.2 arcminutes.
52
Why do stars appear to rise and set?
Because Earth rotates daily, making celestial objects appear to move across the sky.
53
What are circumpolar stars?
Stars near the north celestial pole that remain perpetually above the horizon.
54
What happens to stars near the south celestial pole?
They never rise above the horizon.
55
What is the Moon Illusion?
The phenomenon where the full moon appears larger when near the horizon than when high in the sky.
56
What causes the Moon Illusion?
It occurs within the human brain; the Moon's angular size remains essentially the same throughout the night.
57
How does latitude affect the constellations we see?
It affects the locations of the horizon and zenith relative to the celestial sphere.
58
What is latitude?
A measure of north-south position on Earth, defined as 0° at the equator and increasing to 90°N at the North Pole.
59
What is the relationship between the altitude of the celestial pole and latitude?
The altitude of the celestial pole in your sky is equal to your latitude.
60
What is the zodiac?
The constellations along the ecliptic that the Sun appears to move through during the year.
61
What causes the seasons on Earth?
The tilt of Earth's axis causes sunlight to fall differently on Earth at different times of year.
62
What happens in the Northern Hemisphere during June?
It is tipped toward the Sun, experiencing summer.
63
What is the effect of the Sun's angle on seasons?
A steeper angle leads to more concentrated sunlight and longer daylight hours, causing warmer temperatures.
64
What is the brightness of Polaris compared to other stars?
Polaris is not the brightest star; more than 50 stars are just as bright or brighter.
65
What causes the seasons on Earth?
Earth's axis tilt
## Footnote
The seasons are caused by the Earth's axial tilt, not by variations in distance from the Sun.
66
What is the sunlight angle's effect on the Northern Hemisphere during summer?
More hours of daylight, longer and higher Sun path
## Footnote
The steeper angle of sunlight results in more concentrated sunlight and longer daylight hours.
67
What happens to the sunlight angle as Earth orbits the Sun?
It gradually changes
## Footnote
This change affects the amount of sunlight received by each hemisphere throughout the year.
68
When does the June solstice occur?
Around June 21
## Footnote
This is when the Northern Hemisphere is tipped most directly toward the Sun.
69
What is the December solstice and when does it occur?
The winter solstice in the Northern Hemisphere, around December 21
## Footnote
This marks the moment when the Northern Hemisphere receives the least direct sunlight.
70
What are the March and September equinoxes?
March equinox around March 21, September equinox around September 22
## Footnote
These are the moments when both hemispheres are illuminated equally.
71
What does the term 'equinox' mean?
Equal night
## Footnote
Occurs on the two days when the Sun is above and below the horizon for equal times of 12 hours.
72
What is an analemma?
The figure 8 shape made by the Sun's path over a year
## Footnote
It results from Earth's axis tilt and varying orbital speed.
73
Why is the June solstice considered the first day of summer in the Northern Hemisphere?
It is when the Sun reaches its highest point in the sky
## Footnote
The warmest summer weather typically comes 1 to 2 months later.
74
What is the climate difference between the Northern and Southern Hemispheres?
Northern Hemisphere has more extreme seasons
## Footnote
The Southern Hemisphere's larger ocean areas moderate its climate.
75
What is precession?
A gradual wobble that alters the orientation of Earth's axis
## Footnote
Each cycle of Earth's precession takes about 26,000 years.
76
Does precession affect the amount of Earth's axis tilt?
No
## Footnote
Precession changes the direction the axis points but not the tilt itself.
77
What is the effect of Earth's axial tilt on seasons?
It causes the two hemispheres to take turns being tipped toward the Sun
## Footnote
This results in opposite seasons in the Northern and Southern Hemispheres.
78
What are the characteristics of seasons at high latitudes?
More extreme seasons
## Footnote
For example, longer summer days and longer winter nights.
79
What are the typical seasons in equatorial regions?
Rainy and dry seasons
## Footnote
These regions do not experience the four seasons typical of higher latitudes.
80
Why do astrological Sun signs not match the actual positions of the Sun today?
Due to Earth's precession
## Footnote
Astrological signs are based on the positions of the Sun among the stars as they were nearly 2000 years ago.
81
How does the gravitational effect of the Sun and Moon influence Earth's precession?
It causes the axis to precess but not straighten out
## Footnote
The gravitational tugs attempt to align the axis with the ecliptic plane.
82
What is the cycle of lunar phases?
About 29.5 days
## Footnote
This period marks the time it takes for the Moon's appearance to change as it orbits Earth.
83
What is the significance of the Tropic of Cancer?
It marks the latitude where the Sun is directly overhead on the June solstice
## Footnote
This latitude was named when the Sun appeared in the constellation Cancer during the solstice.
84
What happens at the Arctic Circle during the June solstice?
The Sun remains above the horizon all day long
## Footnote
This phenomenon is due to the tilt of the Earth's axis.
85
What type of seasons do planets with more elliptical orbits experience?
More extreme seasonal variations
## Footnote
Mars, for example, has greater seasonal extremes due to its elliptical orbit.
86
What is the time period marking the cycle of lunar phases?
About 29.5 days
## Footnote
This period is also the origin of the word 'month', which relates to 'moonth'.
87
How does the Moon's movement compare to the Sun's movement through the zodiac?
The Moon moves at a rate of about 360° per month, or its own angular size each hour.
88
What is the first step in understanding lunar phases?
Recognizing that sunlight comes from the same direction for both Earth and the Moon.
89
What is synchronous rotation?
The Moon rotates on its axis in the same amount of time it takes to orbit Earth.
90
What happens during a lunar eclipse?
Earth comes directly between the Sun and Moon, causing Earth's shadow to fall on the Moon.
91
What occurs during a solar eclipse?
The Moon comes directly between the Sun and Earth, causing the Moon's shadow to fall on Earth.
92
What are the two distinct regions of an eclipse shadow?
* Umbra
* Penumbra
93
What are the three types of lunar eclipses?
* Total lunar eclipse
* Partial lunar eclipse
* Penumbral lunar eclipse
94
What causes a total lunar eclipse to appear red during totality?
Earth's night side is surrounded by the reddish glow of all the sunrises and sunsets occurring on Earth.
95
What are the three types of solar eclipses?
* Total solar eclipse
* Annular solar eclipse
* Partial solar eclipse
96
What is the typical speed of the Moon's shadow as it moves across Earth during a solar eclipse?
About 1700 kilometers per hour.
97
What is the term for the illumination of the dark portion of the Moon's face?
Ashen light or earthshine.
98
What is the difference between waxing and waning phases of the Moon?
Waxing means 'increasing', while waning means 'decreasing'.
99
Fill in the blank: The phases just before and after new moon are called ______.
crescent
100
Fill in the blank: The phases just before and after full moon are called ______.
gibbous
101
True or False: The Moon's synchronous rotation is a coincidence.
False
102
What is the reason we always see the same face of the Moon from Earth?
The Moon rotates once in the same time it takes to orbit Earth.
103
How does the Moon's phase affect its visibility in the sky?
Different phases determine the times of day at which we see the Moon.
104
What does the term 'gibbous' literally mean?
Hump-backed.
105
What is the significance of the curvature of Earth's shadow during a total lunar eclipse?
It demonstrates that Earth is round.
106
True or False: A solar eclipse can be seen from anywhere on Earth.
False
107
What alignment is needed for a total lunar eclipse to occur?
Sun, Earth, and Moon must be nearly perfectly aligned.
108
Fill in the blank: The combination of Earth's rotation and the Moon's orbital motion causes the Moon's shadow to race across Earth at a typical speed of about ______.
1700 kilometers per hour
109
What is the best way to visualize the Moon's orbit in relation to Earth's orbit?
Imagine the Moon's orbit is inclined by about 5° to the ecliptic plane.
110
What is the reason eclipses do not occur every month?
The Moon’s orbit is inclined by about 5° to the ecliptic plane.
111
What are the two points where the Moon crosses the ecliptic plane called?
Nodes.
112
During which lunar phases can eclipses occur?
* New Moon (solar eclipse)
* Full Moon (lunar eclipse)
113
What are eclipse seasons?
Periods when the nodes are closely aligned with the Sun and Earth.
114
How long does an eclipse season last on average?
About five weeks.
115
What is the phenomenon called when the Moon's nodes slowly move around its orbit?
Precession of the nodes.
116
What is the saros cycle?
A cycle of about 18 years in which eclipses recur.
117
Who were the ancient cultures that successfully predicted eclipses?
* Babylonians
* Mayans
118
What is the average time between successive eclipse seasons?
About 173 days.
119
What is the effect called that allows us to see about 59% of the Moon's surface over a month?
Libration.
120
True or False: Eclipses can only occur when the Moon is at a node.
True.
121
Fill in the blank: The average human menstrual cycle is close in length to a _______.
Lunar month.
122
What might be a physiological pattern linked to lunar phases?
Some crabs and turtles lay eggs only at full moon.
123
What does the term 'paths of totality' refer to?
The paths where total solar eclipses are visible.
124
What is the significance of the full moon in relation to human behavior?
There is no scientific evidence to suggest direct effects.
125
What causes the visible face of the Moon to appear to wobble?
The variation in the Moon’s orbital speed in accordance with Kepler’s second law.
126
What can affect the visibility of solar eclipses?
The Moon’s orbital distance at the time of the eclipse.
127
What did Thales predict about eclipses?
He predicted the year of a total eclipse in ancient Turkey.
128
Why is predicting eclipses considered difficult?
Changing dates of eclipse seasons and lunar phases.
