Chapter 3 - Science

Question 1

Aphelion

Answer 1

The point in a planet’s orbit where it is farthest from the sun

Question 2

Perihelion

Answer 2

The point in a planet’s orbit where it is closest to the sun

Question 3

Apogee

Answer 3

The point in a moon’s orbit where it is furthest from the planet

Question 4

Perigee

Answer 4

The point in a moon’s orbit where it is closest to the planet

Question 5

Bound orbit

Answer 5

An orbit in which an object orbits another object repeatedly

Question 6

Unbound orbit

Answer 6

An orbit in which an object passes by another object once and then never again

Question 7

Eccentricity

Answer 7

How much an orbit deviates from a perfect circle

Question 8

Escape velocity

Answer 8

The minimum speed needed to escape an object’s gravity from a certain point

Question 9

Orbital period

Answer 9

How long an object takes to complete one orbit

Question 10

Semimajor axis

Answer 10

The longer axis of an object’s orbit

Question 11

Aristotle

Answer 11

Believed that the Earth was the center of the universe and everything else orbited it in perfect circles

Question 12

Ptolemy

Answer 12

Developed the “circles on circles” model of the universe to explain apparent retrograde motion

Question 13

Copernicus

Answer 13

Developed a heliocentric model of the universe where the Earth orbited the sun in perfect circles

Question 14

Galileo

Answer 14

Supported the heliocentric model with observational evidence
Discovered several moons of Jupiter

Question 15

Isaac Newton

Answer 15

Developed three laws of gravity which describe gravitational forces within the solar system with reasonable accuracy

Question 16

Johannes Kepler

Answer 16

Used Brahe’s observations to develop three laws of planetary motion
Suggested that planets did not orbit in perfect circles

Question 17

Tycho Brahe

Answer 17

Made extremely detailed observations of the motion of stars, comets, and planets over many years

Question 18

What is Kepler’s First Law of Planetary Motion?

Answer 18

Planets orbit the sun in an elliptical orbit with the sun at one focus

Question 19

What is Kepler’s Second Law of Planetary Motion?

Answer 19

A planet sweeps out equal areas of its orbit in equal times

Application: planets orbit faster when farther from the sun and slower when closer to the sun

Question 20

What is Kepler’s Third Law of Planetary Motion?

Answer 20

A planet’s orbital period is proportional to the length of its semimajor axis

Orbital period squared = semimajor axis cubed