Chapter 2: Discovering the Universe for Yourself

Question 1

a region of stars with well-defined borders

Answer 1

constellation

Question 2

the imaginary sphere on which objects in the sky appear to reside when observed from Earth

Answer 2

celestial sphere

Question 3

the point on the celestial sphere directly above Earth’s North Pole

Answer 3

north celestial pole

Question 4

the point on the celestial sphere directly above Earth’s South Pole

Answer 4

south celestial pole

Question 5

the extension of Earth’s equator onto the celestial plane

Answer 5

celestial equator

Question 6

the Sun’s apparent annual path among the constellations

Answer 6

ecliptic

Question 7

the sky as seen from wherever you happen to be standing

Answer 7

local sky

Question 8

a boundary that divides what we can see from what we cannot see

Answer 8

horizon

Question 9

the point directly overhead, which has an altitude of 90 degrees

Answer 9

zenith

Question 10

a half-circle extending from your horizon due south, through your zenith, to your horizon due north

Answer 10

meridian

Question 11

one of the two coordinates needed to pinpoint an object in the local sky; the direction, such as north, south, east, or west, in which you must face to see the object

Answer 11

direction

Question 12

the angular distance between the horizon and an object in the sky

Answer 12

altitude

Question 13

a measure of the angle formed by extending imaginary lines outward from our eyes to span an object

Answer 13

angular size

Question 14

a measure of the angle formed by extending imaginary lines outward from our eyes to span the space between two objects

Answer 14

angular distance

Question 15

1/60 of 1 degree

Answer 15

arcminutes

Question 16

1/60 of an arcminute

Answer 16

arcseconds

Question 17

a star that always remains above the horizon for a particular latitude

Answer 17

circumpolar star

Question 18

the angular north-south distance between Earth’s equator and a location on Earth’s surface

Answer 18

latitude

Question 19

the angular east-west distance between the prime meridian and a location on Earth’s surface

Answer 19

longitude

Question 20

the meridian of longitude that passes through Greenwich, England; defined to be longitude 0 degrees

Answer 20

prime meridian

Question 21

the constellations on the celestial sphere through with the ecliptic plane passes

Answer 21

zodiac

Question 22

the moment when the Northern Hemisphere is tipped most directly toward the Sun and receives the most direct sunlight

Answer 22

summer solstice

Question 23

the moment when the Northern Hemisphere receives the least direct sunlight

Answer 23

winter solstice

Question 24

the moment when the Northern Hemisphere goes from being tipped slightly away from the Sun to being tipped slightly toward the Sun

Answer 24

spring equinox

Question 25

the moment when the Northern Hemisphere first starts to be tipped away from the Sun

Answer 25

fall equinox