LECTURE 2

Question 1

How is our sun moving in the galaxy?

Answer 1

The sun moves in a random pattern and at a speed of 70,000km/h
The sun orbits the Milky Way once every 230 million years
The suns’ speed of rotation around the galaxy is 800,000km/h

Question 2

The angle which Earth is tilted towards

Answer 2

23.5 degrees

Question 3

In which direction does Earth rotate

Answer 3

From West to East
Counterclockwise

Question 4

How do galaxies move within the universe?

Answer 4

Of the galaxy as baking bread with raisins in it, the raisins do not increase in size but the distance between the raisins will increase as the size of the bread increases

Question 5

Who discovered that the universe is expanding?

Answer 5

Vesto Slipher 1917
Carl Wirtz 1918
Knut Lundmark 1920
Edwin Hubble 1929

Question 6

How is Earth moving in our solar system?

Answer 6

Rotates on its axis once a day
Orbits the sun at a distance of 1AU

Question 7

Scientific Thinking

Answer 7

everyday ideas of observation and through trial and error experiences

Question 8

What did ancient civilizations achieve in astronomy?

Answer 8

Tracking the seasons
Daily timekeeper
Calendar
Monitoring lunar cycles
Monitoring planets and stars
Predicting eclipses

Question 9

How did astronomical observations benefit ancient societies?

Answer 9

Keeping track of time and seasons
- Agriculture

Question 10

The Nebra Sky Disk

Answer 10

1800-1600BC
Contains symbols for the Sun or full moon
The Crescent Moon
Pleiades (group of stars)

Question 11

Crab nebula

Answer 11

65000 LY away
Observed in 1054 by Chinese Astronomers

Question 12

Why does modern science trace its roots to the Greeks?

Answer 12

Developed models of nature and emphasized that the predictions of models should agree with observations

Question 13

How did the Greeks explain planetary motion?

Answer 13

Earth is at the centre of the universe
Heavens must be perfect Objects moving on perfect spheres

Question 14

Ptolemaic Model

Answer 14

Sufficiently accurate remain in use for 1,500 years

Question 15

Ptolemaic Model

Answer 15

EACH PLANET MOVE ON A SMALL CIRCLE WHOSE CENTER MOVES AROUND EARTH ON A LARGER CIRCLE

Question 16

Aristarchus Samos

Answer 16

310-230 BC
Proposed model of the solar system
Estimated size and distance of the sun and the moon

Question 17

Nicolaus Copernicus

Answer 17

Proposed a Sun-centred model (1543)
Used model to determine the layout of the solar system

Question 18

Tycho Brahe

Answer 18

The most accurate naked eye ever made of planetary positions
Thought that Earth is at the center of the solar system but recognized that other planets go around the sun

Question 19

Johannes Kepler

Answer 19

tried to match Tycho’s observations with circular orbits
8 arcminute discrepancy led him eventually to ellipses

Question 20

What is an ellipse?

Answer 20

An elongated circle (oval)

Question 21

Kepler’s First Law

Answer 21

1609
The orbit of each planet around the Sun is an ellipse with the sun at one focus

Question 22

Kepler’s second law

Answer 22

1609
As a planet moves around its orbit it sweeps out equal areas at equal times

Question 23

Kepler’s third law

Answer 23

1619 The farther a planet is from the sun the slower its orbital speed is and vice versa