Unit Nine - Astronomy - Apparent Motion

Question 1

What is the Geocentric Universe?

Answer 1

The idea that the Earth was the center of the solar system.

Question 2

What were problems and flaws about the idea of a Geocentric Universe?

Answer 2

1. Locations of planets couldn’t accurately be predicted
2. Changes in the apparent diameter of the Moon and Sun couldn’t be explained

Question 3

Definition of Celestial Object

Answer 3

Any natural objects that appears to move across the sky

Question 4

How many degrees do most planets rotate PER HOUR?

Answer 4

15

Question 5

Definition of Apparent Motion

Answer 5

How celestial objects appear to move across the sky

Question 6

Definition of Celestial Sphere

Answer 6

The visible portion of the sky that celestial objects appear to travel on

Question 7

Definition of Horizon

Answer 7

The edge of the visible portion of the celestial sphere

Question 8

Definition of Zenith

Answer 8

The highest point on the celestial sphere which is directly over the observer

Question 9

Where do all object appear to move in the sky (except Polaris which stays in the same place)?

Answer 9

East to West

Question 10

Definition of Polar Stars

Answer 10

Stars that are found directly above the Poles.

Question 11

Definition of Star Trails

Answer 11

Long exposure photos of stars that show the direction of movement across the sky

Question 12

How can star trails determine which hemisphere the photo was taken?

Answer 12

Northern Hemisphere - Stars would be rotating CLOCKWISE around the central star (polaris)

Southern Hemisphere - Stars would be rotating COUNTERCLOCKWISE around the central star (polaris)

Equator - Central Star (Polaris) is directly found on the horizon (only half of the circular shape of the star trail can be shown)

Question 13

Definition of Altitude

Answer 13

Angular distance ABOVE the horizon (0 - 90)

Question 14

Definition of Azimuth

Answer 14

Angular distance ALONG the horizon (0 - 360)

North - 0 degrees
East - 90 degrees
West - 270 degrees
South - 360 degrees

Where you are horizontally

Question 15

What two things does the sun’s path affect?

Answer 15

Length of Sunlight/Day & Season

Question 16

What is the relationship between sunlight time and the sun’s path?

Answer 16

1. The LONGER the sun’s path, the INCREASED amount of daylight hours an area receives
2. The SHORTER the sun’s path, the DECREASED amount of daylight hours an area receives

Question 17

When is the Sun’s shadow at its largest and at its smallest.

Answer 17

1. Least Shadow - Noontime Sun
2. Most Shadow - Sunrise & Sunset