Sept. 6th - The local sky and celestial sphere

Question 1

Stars remain the same; patterns of them are referred to as…

Answer 1

constellations: a region of the sky with well-defined borders; the familiar patterns of stars merely help us locate the constellation

Question 2

Celestial Sphere

Answer 2

• Stars can appear to be close to one another, yet realistically, are far apart as they lie at different distances from Earth - due to our lack of depth perception in space
• Ancient Greeks mistook this as an illusion for reality, imagining the stars and constellation to lie on a great celestial sphere that surrounds Earth

Question 3

Every object in the celestial sphere appears to…

Answer 3

make a simple daily circle around earth - however, the motion can look more complex in the local sky as the horizon cuts the celestial sphere in half

Question 4

Stars near the north celestial pole are…

Answer 4

circumpolar: they remain perpetually above the horizon, circling counter-clockwise around the north celestial pole each day

Question 5

All other stars have daily circles that are

Answer 5

partly above and below the horizon, meaning that they seem to rise in the east and set in the west

Question 6

North Celestial Pole

Answer 6

point directly over the earth’s North pole

Question 7

South Celestial Pole

Answer 7

point directly over the earth’s South pole

Question 8

Celestial Equator

Answer 8

projection of earth’s equator into space

Question 9

Ecliptic

Answer 9

the path the Sun follows as it appears to circle around the celestial sphere once each year

Question 10

The Milky Way in the night sky traces our galaxy’s…

Answer 10

disk of stars - the galactic plane - as it appears from our location within the milky way galaxy

Question 11

Local Sky

Answer 11

the sky as seen from wherever you happen to be standing

• Takes the shape of a hemisphere or dome - coming from the fact that we only see half of the celestial sphere at any particular moment from any particular location, while the ground blocks the other half from the view

Question 12

How can we can pinpoint the position of any object in the local sky

Answer 12

by stating its direction along the horizon, and altitude above it

Question 13

Why do the constellations we see depend on the latitude and time of each year?

Answer 13

The reason we don’t see stars during the day is because their dim light is overwhelmed by the bright daytime sky - otherwise, they are always there

Question 14

Latitude

Answer 14

north-south position on earth

Question 15

Longitude

Answer 15

east-west position on earth