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Astronomy > Exam 2 > Flashcards

Exam 2 Flashcards

1
Q

How many seconds in a day

A

86,400

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2
Q

Why do we sometimes have an extra day in a year

A

because if we didn’t, we would be off track with the seasons

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3
Q

Where does the sun rise and set on the first day of fall and spring

A

Due east and due west

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4
Q

Longest day of the year

A

Summer solstice

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5
Q

Shortest day of the year

A

Winter solstice

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6
Q

Tropical year

A

Year based on the seasons; 365 days, 5 hours, 48 minutes, and 45 seconds

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7
Q

Why is a solar day longer than a sidereal day?

A

Because the earth doesn’t rotate in exactly 24 hours; the extra 4 minute difference makes up that distance

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8
Q

Why does the moon go through its cycle of phases?

A

Because the earth rotates and revolves at the same time

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9
Q

Why do the sun, moon, and planets always appear on/around the ecliptic?

A

Because everything in the solar system is essentially on the same plane

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10
Q

Why do the sun, moon, planets, and stars move counter clockwise around the sky once per day?

A

Because the Earth rotates

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11
Q

Why does the Earth have seasons?

A

Because of the altitude of the sun. The higher the sun is in the sky, the warmer it will be

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12
Q

Opposition

A

you look one way to see something and look the opposite way to see something else

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13
Q

When does retrograde motion happen

A

When an object is at opposition

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14
Q

Conjunction

A

When something is exactly lined up with something else

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15
Q

Inferior conjunction

A

when something is in front of and lined up with something

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16
Q

Superior conjunction

A

something is behind of and lined up with something

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17
Q

Quadrature

A

When something is at a 90-degree angle in respect to the sun

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18
Q

Greatest elongation

A

where something is at the highest angle it can be

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19
Q

Greatest elongation of Mercury

A

23 degrees

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20
Q

Greatest elongation of Venus

A

47degrees

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21
Q

Which planets can be at any planetary configuration

A

Mars, Jupiter, and Saturn

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22
Q

Which planets cannot be at any planetary configuration and why

A

Mercury and Venus cannot be in every position because they are always close to the sun

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23
Q

Does the sun rise exactly due east and set exactly due west every day at the equator

A

No

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24
Q

Aristotle

A

Imagined the earth at the center of the universe with everything revolving around it

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25
Q

Ptolemy

A

 Accurately traced the paths of the planets using epicycles • All perfect circles  Earth at the center with planets going around in epicycles  150 AD  Lived in Alexandria  Wrote Almagest

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26
Q

Copernicus

A

 Created the idea of heliocentrism – sun centered solar system  Wrote The Revolution of the Celestial Orbs in 1543  Also insisted that the earth rotated every 24 hours  1500’s  his model explains why venus and mercury stay near the sun – because their orbits are smaller than earth’s

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27
Q

Tycho Brahe

A

 He built an observatory (Uranobor) in Denmark  First true observational astronomer  Made the most detailed layout of the solar system of his time

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28
Q

Kepler

A

 1610  Maintained the idea that the sun was the center of the solar system  Hypothesized that the planets traveled in ellipses  Also discovered as the planets get closer to the sun, they speed up and as they get further away, they slow down  Published the book New Astronomy about Mars in 1609 • Summarized the way the Earth travels around the sun and the 3 laws regarding that

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29
Q

Who was the first to find the circumference and radius of the earth

A

Eratosthenes

30
Q

circumference of the earth

A

25,000 mi

31
Q

Radius of the earth

A

4,000 mi

32
Q

Eccentricity

A

how “ellipse” something is Circular is 0 eccentricity, 1 is the highest eccentricity

33
Q

Kepler’s 1st Law

A

Elliptical orbits and the sun is not the center of the solar system

34
Q

Kepler’s 2nd Law

A

Planets will move faster as they get closer to the sun

35
Q

Kepler’s 3rd Law

A

How a planet’s orbit size is compared to its size (p^2 = a^3)

36
Q

Order of the planets

A

Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune

37
Q

How long does it take the earth to rotate once completely

A

23 hours and 56 minutes (sidereal day)

38
Q

How long does it take the moon to go through its phases

A

29.5 days (synodic period)

39
Q

How long does it take the moon to go through the constellations of the zodiac

A

27.3 days (sidereal period)

40
Q

How many degrees does the moon go around for it to go from full moon to full moon

A

360 + 30 degrees

41
Q

The moon’s orbit is very nearly circular.

A

True

42
Q

Earth is at the very center of the moon’s orbit.

A

False

43
Q

When the moon is close to Earth, the moon appears slightly ___________ than average.

A

Bigger

44
Q

What is the eccentricity of the moon’s orbit? Enter your answer as a decimal number.

A

.055

45
Q

The date of the vernal equinox is [month] [day].

A

March 21

46
Q

The date of the summer solstice is [month] [day].

A

June 21

47
Q

The date of the autumnal equinox is [month] [day].

A

September 21

48
Q

The date of the winter solstice is [month] [day].

A

December 21

49
Q

We add a leap day to our calendar every 4 years.

A

False, not every four years

50
Q

Presently, one second is defined as

A

1/86,400 of the mean solar day

51
Q

Sally says she saw the full moon in the constellation Cassiopea…


A

True becasue everything in our solar system passes through the Zodiac constellations

52
Q

Which of the following planets can be observed at opposition?

A

Mars, Jupiter, and Saturn

53
Q

Which of the following planets can be observed at quadrature?

A

Mars, Jupiter, and Saturn

54
Q

What can be concluded from this graph? (Grand Haven Graph)

A

Earth’s rotation rate is gradually slowing

55
Q

Which of the planets is/are observed to undergo “retrograde loops” in their motion against the background stars?

A

Mars, Jupiter, and Saturn

56
Q
A
57
Q

Do the yearly average sunrise/set time and the average length of day/night vary with latitude? In other words, do observers at different latitudes see different average sunrise/set times andaverage lengths of days?

A

It is apparent from the data that the average time of sunrise/set and the average length of the day is the same for all observers on Earth. On the spring and fall equinoxes, the sun rises due east at 6 am and sets due west at 6 pm everywhere on Earth!

58
Q

Do the +/- variation in sunrise/set time and the +/- variation in the length of the day/night depend on latitude? If so, describe in what sense. For example, if you find that the variation in sunrise/set time decreases the further north you are from the equator, than write something to that effect – and support your conclusion with data from the class-data spreadsheet.

A

The variation (about the average) of the sunrise/set time and the length of day/night both increase with increasing latitude. Near the equator, there is very little variation in the time of sunrise/set and the length of the day/night; closer to the poles, the variation increases. For example in Alaska, the variation in sunrise/set time is 4 or 5 hours, making the summer solstice day, and the winter solstice night, 20 to 22 hours long! North of the arctic circle, the sun doesn’t set for several (or more) in the summer and doesn’t rise for several (or more) days in the winter.

59
Q

Does the average azimuth of sunrise/set depend on latitude? Support your answer using the data collected in class.

A

The average azimuth of sunrise/set does not depend on latitude. All observers on Earth see the sun rise/set at the same place on the horizon: due east and due west.

60
Q

Does the +/- variation in sunrise/set azimuth depend on latitude? Write an answer, supported with data from the class-data spreadsheet, as in the previous question.

A

The +/- variation in sunrise/set azimuth does depend on latitude. Near the equator, the variation is minimal – BUT NOT ZERO. (It turns out to be +/- 23 degrees). Further north, the variation in sunrise/set azimuth increases; for example, in Grand Rapids it is about +/- 30 degrees and in Alaska it is about +/- 60 (or more) degrees.

61
Q

Does the average altitude of the sun at solar noon vary with latitude? Support your answer (quantitatively, if you can) using the data collected in class.

A

The average altitude of the sun at solar noon – the altitude of the sun on the equinoxes – decreases with increasing latitude. In other words, the sun at noon on the eqinoxes is very high in the sky near the equator, and lower in the sky further north. For example, the equinox altitude of the sun at noon on the equator is 90 degrees, while on the same day in Grand Rapids it is only 47 degrees.

The altitude of the sun at noon on the equinoxes is related to latitude in a simple way: equinox noon-sun altitude equals 90 degrees minus latitude.

62
Q

Does the +/- variation in the altitude of the sun at noon depend on latitude? Write an answer, supported with data from the class-data spreadsheet, as in the previous question.

A

The +/- variation of the sun at noon does NOT depend on latitude: all observers see the same variation over the year. The sun is 23 degrees higher (compared to on the equinox) in the summer and 23 degrees lower in the winter.

63
Q

On Earth’s equator days and nights are nearly equal in length – 12 hours each – every day of the year.

A

True

64
Q

For an observer on Mars could Earth ever be at opposition?

A

No

65
Q

When Jupiter is in conjunction as viewed from Earth, in which planetary configuration is Earth if viewed from Jupiter?

A

Superior conjunction.

66
Q

In what planetary configuration is Mars (as viewed from Earth, of course) when Mars is closest to Earth?

A

Opposition

67
Q

The variation in the times of sunrise and sunset over the course of a year for an observer in Grand Rapids is about +/- [h] hours and [m] minutes.

A

1 hr 30 min

68
Q

The variation in the altitude of the sun at solar noon over the course of a year for an observer in Grand Rapids is about +/- [d]degrees.

A

23

69
Q

Consider by how much the azimuth of the sunrise/set points vary over the seasons, for an observer at the mid latitudes. By how many degrees would you say the most extreme sunrise and sunset azimuths differ from due east and due west? As a point of reference, keep in mind that the directions northeast and due east differ by 45 degrees.

A

30 degrees

70
Q
A

Astronomy (7 decks)

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