Terms For Earth Science Chapter 1 Activity 3 (Book 2)

Front 1

Kepler's first law of planetary motion

Back 1

each planet orbits around the Sun in an ellipse with the Sun at one focus

Front 2

Kepler's second law of planetary motion

Back 2

planets cover equal distances in equal times throughout their orbits

Front 3

Kepler's third law of planetary motion

Back 3

the time a planet takes to complete an orbit is related to its average distance from the Sun

Front 4

Eccentricity

Back 4

the ratio of the distance to the foci and the length of the major axis of an ellipse (how oval a shape is) - a perfect circle has an eccentricity of 0, and a straight line has an eccentricity of 1

Front 5

Most elliptical orbits

Back 5

Pluto and Mercury; although Pluto does sometimes cross into Neptune's orbit

Front 6

coma

Back 6

a spherical cloud of material surrounding the head of a comet that has a high eccentricity

Front 7

Change in axial tilt (obliquity)

Back 7

every 41,000 years, the axial tilt of the earth varies from 22.1 to 24.5 which creates a wider range of temperature in the seasons

Front 8

precession

Back 8

differences in gravitational pull create a wobble that takes about 25,725 years to change the timing of the seasons

Front 9

orbital precession

Back 9

the rotation of the earth's orbit around the sun (a wobble)

Front 10

precession of the equinoxes

Back 10

the combined axial and orbital precessions every 22,000 years which would change the timing of the seasons and make winters colder and summers warmer

Front 11

event every 10,000 years

Back 11

winter would occur during summer months and summer during winter months (winter would be from June to September)

Front 12

orbital plane

Back 12

the plane formed by the path of the earth around the sun

Front 13

inclination

Back 13

the angle between the orbital plane of the solar system and the actual orbit of an object around the sun (related to eccentricity)

Front 14

asteroid belt

Back 14

area between orbits of Mars and Jupiter with asteroids

Front 15

effect of collision with comet's tail

Back 15

this collision would not be too harmful to the earth because the tail of a comet is composed mainly of glowing gas with very little mass

Front 16

perihelion

Back 16

(January 5th - Northern Hemisphere winter) the point where the earth's axis is tilted away from the sun

Front 17

aphelion

Back 17

(July 5th - Northern Hempisphere summer) the point where the earth's axis is tilted towards the sun