Objectives

Question 1

What is the origin of the names of the days of the week?

Answer 1

7 Heavenly bodies which wander relative to fixed background stars. (Sun, Moon, Mars, Mercury, Jupiter, Venus, Saturn)

Question 2

Parallax

Answer 2

An apparent change in position of an object due to an actual change in position of the observer.

Question 3

Geocentric

Answer 3

An earth centered system

Question 4

Heliocentric

Answer 4

A sun-centered system

Question 5

Retrograde Motion

Answer 5

Planets seem to periodically reverse the direction of their wandering in the sky as the Earth passes by them in orbit with a greater velocity.

Question 6

What is the diameter of the Earth?

Answer 6

Approximately 8,000 miles

Question 7

Eratosthenes

Answer 7

Best early determination of Earth’s size

Question 8

Ptolemy

Answer 8

Used epicycles to explain retrograde motion in geocentric system

Question 9

Copernicus

Answer 9

Made 3 proposals which started Modern Astronomy

Question 10

Tycho Brahe

Answer 10

Great Observer

Question 11

Kepler

Answer 11

Formulated 3 famous laws. Worked w/Tycho

Question 12

Galileo

Answer 12

1st to—
•point telescope towards heavens
•see mtns & craters on moon
•detect 4 largest moons of Jupiter
•phases of Venus
•sunspots

Question 13

3 Proposals made by Copernicus (and their implications)

Answer 13

1. Stars are stationary. —>Earth rotates once daily.
2. Sun is center of universe —>Earth revolves once yearly.
3. Heavenly bodies move in perfect circles at constant speeds. —>epicycles only needed to account for variable speeds.

Question 14

Distinguish between rotation and revolution

Answer 14

Rotation—spin around axis

Revolution—orbit around a body/focus

Question 15

6 Proofs that Earth rotates

Answer 15

1. Satellites in low Earth orbits change positions relative to Earth’s surface on each pass b/c satellite maintains original path while Earth rotates beneath it.
2. Foucault pendulum
3. Oblate spheroid shape of Earth.
4. Falling objects fall to the East.
5. Moon approaches at 600mph at moonrise; recedes at same rate at moonset.
6. All weather formations are rotating. Effect of Coriolis forces.

Question 16

Proofs of revolution

Answer 16

1. Stellar Parallax. (The stars make little aloops.)
2. Aberration of Starlight. Astronomers must tilt telescope to compensate for Earth’s rotational orbit.
3. Certain stars approach us at one time, 6mo later receding.

Question 17

Distinguish: Solar day & Sidereal day

Answer 17

Solar day: Measured w/respect to sun. 24hrs long.

Sidereal day: Measured w/respect to stars. (4min less)

Question 18

Earth’s precessional angle

Answer 18

23.5° from vertical plane of orbit

Polaris is current N star

Seasons are result

Question 19

Significance of Tropics of Cancer and Capricorn

Answer 19

Tropic of Cancer: Most N line on Earth’s surface where Sun rays hit vertically.

Tropic of Capricorn: Most S line where Sun directly overhead.

Question 20

Arctic and Antarctic Circles

Answer 20

Arctic Circle: most S line in N hemisphere which can have sunlight for full 24hrs.

Antarctic Circle: most N line in S hemisphere that gets sunlight for full 24hrs.

Question 21

Day, week, month, and year in astronomical terms.

Answer 21

Day: One rotation of Earth

Week: Possibly b/c 7 heavenly wanderers

Month: Moon’s revolution once around Earth

Year: One revolution of Earth around sun

Question 22

Newton’s law of gravitation

Answer 22

F= (GMeMs)/(r^2)

Question 23

4 Proofs that Earth is approx. spherical

Answer 23

1. If flat—> objects moving away would only get smaller. B/c Earth has curvature—>objects slowly disappear over horizon.
2. Shadow of Earth on moon is circular during an eclipse.
3. Magellan’s voyage around world
4. Pictures from space

Question 24

Diameter of moon; distance to moon

Answer 24

2140; 240,000mi

Question 25

One lunar day from sun rise to sunset in terms of earth time.

Answer 25

One earth month

Question 26

Why does size of moon vary over 2 weeks?

Answer 26

Elliptical orbit

Question 27

Density of moon

Answer 27

3.3 g/cc

Question 28

Does the moon have a magnetic field?

Answer 28

No, the moon has no magnetic field.

Question 29

Moon has same rate of rotation and revolution because it is

Answer 29

Tidally locked to the earth.

Question 30

Spring Tides

Answer 30

* When high tide occurs at the time of New Moon, sun and moon pull together to form high tide (higher than average). * Also occur at Full Moon

Question 31

Neap Tides

Answer 31

* Lower than average high tide * during 1st & 3rd quarters * Moon forms high tide, while sun forms high rude where moon causes low. Work against each other.

Question 32

Why don't eclipses occur monthly?

Answer 32

Because there is a 5° angle between the orbital plane of Earth and orbital plane of the moon.

Question 33

Annular eclipse

Answer 33

Moon is lined up w/Sun but ring of light peeks out from behind. Happens when moon is farther from earth in orbit.

Question 34

Total eclipse

Answer 34

When moon entirely blacks out sun. | Happens when moon is closer in orbit.

Question 35

Relation between moon's lack of limb darkening and surface.

Answer 35

Moon has no limb darkening b/c rough surface edges of moon cause it to not be noticeably dimmer. (Rough surface also indicates low reflectivity.) Rough on large scale: mtns. & craters Small scale: dust

Question 36

How was it possible to predict the Moon has no atmosphere?

Answer 36

•low gravitational pull. •Low temps @night; high temps @day -atmosphere would act as blanket and reduce extremes -Kinetic theory of gases, gas molecules in high daytime travel faster then moon's escape V 1.7mi/s

Question 37

2 major theories for origin of lunar craters

Answer 37

1. Most Impact craters: when large objects fall onto moon. | 2. Some Volcanic activity

Question 38

Probable origin of lunar maria

Answer 38

* Large impact craters causes by objects hitting the moon when subsurface material was molten. * Molten labs flowed out through hole and covered most existing craters.

Question 39

4 Ways Moon May Have Originated

Answer 39

1. Adopted—formed elsewhere captured in Earth's orbit. 2. Twins—formed & evolved alongside of Earth. 3. Birth—Once a part of Earth. Moon density = Earth's crust density. 4. Catastrophic collision between early Earth and 2nf object size of Mars. (Current Accepted Theory) - Moon composition same as Earth in certain isotopes, but NOT match any bodies in solar system.

Question 40

How were the relative age of craters determined?

Answer 40

Most recent—Copernican age. Freshly pulverized rocks are white. Ray material must be most recently deposited since it covers everything undisturbed.