Quiz 2 Practice

Question 1

Ecliptic

Answer 1

the circular path of the Sun in the sky

Question 2

Zodiac

Answer 2

the area near the ecliptic that includes paths of planets

Question 3

Geocentric

Answer 3

geocentric model, any theory of the structure of the solar system (or the universe) in which Earth is assumed to be at the centre of it all

Question 4

Heliocentric

Answer 4

the astronomical model in which the Earth and planets revolve around the Sun at the center of the universe.

Question 5

Period (P)

Answer 5

time between cycles (one orbit around the Sun)

Question 6

Semi-major axis (a)

Answer 6

the “radius” of an ellipse

Question 7

Astronomical Unit (AU)

Answer 7

the estimated distance from the Earth to the Sun

Question 8

Lightyear (ly)

Answer 8

the length that light can travel in one calendar year

Question 9

Milky Way

Answer 9

the Solar System’s galaxy that is made of billions of stars.

Question 10

How can we use ratios and proportions to scale things down to an understandable size?

Answer 10

smaller measurement/real measurement = smaller measurement/real measurement

Question 11

How big is the Solar System as compared to the Milky Way?

Answer 11

The Solar System is one star, while the Milky Way is billions of stars. We would not be able to pick out the Sun on a picture of the Milky Way (if we could take a picture of the Milky Way).

Question 12

Why did we rule out the geocentric model in favor of the heliocentric model?

Answer 12

The geocentric model was based on some evidence; however, a majority of it was based on the principle that the Earth was God’s creation and was the holiest creation and thus everything in space was centered around it.

The geocentric model could also not explain the retrograde motions of some planets as well as the heliocentric model. Sorry, Ptolemy.

With the use of the telescope he stole, Galileo observed the movement of Jupiter’s moons and realized that the moons orbit Jupiter. This notion of smaller objects orbiting larger objects continued with the moons and other planets.

Question 13

How do we relate period and semi-major axis mathematically?

Answer 13

Kepler developed three laws concerning planetary motion from the precise measurements of his mentor, Brahe. Kepler’s Third Law states that the period of a planet’s orbit squared is proportional to the semi-major axis cubed. P² = a³