Lecture 1

Question 2

what is astronomy defined as?

Answer 2

the study of objects that lie beyond our planet earth and the process by which these objects interact with one another

Question 3

what is a hypothesis?

Answer 3

new models or ideas when they are first proposed are sometimes called hypotheses

Question 4

what is crucial for a hypothesis to be?

Answer 4

a proposed explanation that can be tested

Question 5

by what means do we test a hypothesis in the most straight forward way?

Answer 5

through experimentation whereby the results, if the experiment is conducted properly, will either agree with the predictions in the hypothesis or contradict it.

Question 6

do the test results agreeing with the hypothesis mean that it is correct?

Answer 6

not necessarily as maybe later experiments will prove that crucial parts of the hypothesis are incorrect. but later experiments could also agree with the hypothesis making it more likely that we accept the hypothesis as a useful description of nature.

Question 7

what can the laws of nature be described as?

Answer 7

various scientific laws we have extracted by means of countless observations, hypotheses and experiments. they are the “rules” of the game that nature plays.

Question 8

what is one remarkable discovery about nature as it relates to the laws of nature?

Answer 8

the same laws apply everywhere in the universe.

Question 9

what would be the result of not having universal laws?

Answer 9

we would not be able to make much headway in astronomy.

Question 10

is it impossible for our current scientific models and universal laws to change?

Answer 10

only if new observations and experiments are found that lead to more sophisticated models - models that include new phenomena and laws about their behavior.

Question 11

what is an example of a discovery that changed our scientific models and laws?

Answer 11

The general theory of relativity proposed by Einstein which took place a century ago. it led us to predict and eventually observe a strange new class of objects astronomers call black holes.

Question 12

only what can demonstrate the validity of new scientific models?

Answer 12

the patient process of observing nature ever more carefully and precisely.

Question 13

what is a black hole?

Answer 13

a region of space so intense that no matter or radiation can escape it.

Question 14

what did Einstein’s Theory of General Relativity developed in 1915 show?

Answer 14

that gravity influences the motion of light.

Question 15

what 2 approaches are used to make dealing with astronomical numbers easier?

Answer 15

using scientific notation and using the “light year” and other convenient units.

Question 16

what is the Astronomical unit(AU)?

Answer 16

The average distance from the earth to the sun. AU = 1.5 x 10^8 km. it is used for distances within the solar system.

Question 17

what is the average distance between the earth and the sun?

Answer 17

1 AU or 1,5 x 10^8 km

Question 18

what is the Light year(Ly)?

Answer 18

The distance light travels in 1 year at c = 3x10^5 km/s(300000)

Question 19

how many times around the earth can light travel in 1 second?

Answer 19

7.5 times

Question 20

what is the speed of light(c)?

Answer 20

c - 3x10^5 km/s or 300 000 000 m/s

Question 21

what is the conversion between 1 Ly, AU and distance in km?

Answer 21

1Ly = 63 000 AU = 9,5X10^12 km

Question 22

what is the closest star to the sun?

Answer 22

proxima centauri which is 4.2 Ly away.

Question 23

how far is the moon from earth?

Answer 23

1.3 light seconds

Question 24

how far is the sun form the earth?

Answer 24

8 light minutes

Question 25

how far is the sun from neptune?

Answer 25

4 light hours

Question 26

how far is the sun from polaris?

Answer 26

433 light years

Question 27

how far is the sun form the center of the milky way?

Answer 27

100 000 light years

Question 28

how far is the milky way galaxy from the andromeda galaxy?

Answer 28

2.537 million light years

Question 29

what is the parsec(pc)

Answer 29

if the angle subtended by 1AU is 1 arcsecond, the distance is defined as 1 parsec.

Question 30

1 degree divided into 60 parts gives?

Answer 30

arc minutes(')

Question 31

1' divided into 60 parts gives?

Answer 31

arcseconds('')

Question 32

what is the conversion between 1pc, Light years and distance in kilometers?

Answer 32

1pc = 3.26Ly = 3.1x10^13 Km

Question 33

what is d and p in the formula: d = 1/p?

Answer 33

d is in parsecs when p is in arcseconds. 1 parsec = 3.26 light- years

Question 34

what was a discovery made in 1543 AD?

Answer 34

in 1543 AD, Copernicus became the first person to demonstrate the math behind what is called the "heliocentric model" which was a revolutionary idea that the sun is a star, not a god and we are not located at the center of the universe.

Question 35

what was the first major realization of our place in the universe?

Answer 35

Copernicus's mathematical demonstration of the "heliocentric model". this model eliminated many problems with the older astronomical studies which put earth at the center of the universe.

Question 36

what is kepler's laws and why was it significant in 1609?

Answer 36

Johannes Kepler proved that planets moves around the sun in elliptical orbits, rather than perfect circles. this was revolutionary in 1609 because it meant that the distance between the planets and the sun changed over time and the world finally understood the reason behind the seasons and the apparent motion of planets. without these discoveries astronomers would have had a much more difficult time trying to explain why the suns influence on earth "changes" and why the speeds of other planets seem to vary over time.

Question 37

what discovery was made on Jupiter's moons in 1610 by Galileo and why was this significant?

Answer 37

Galileo discovered 4 moons of Jupiter in 1610 using a telescope he designed and created himself. they were the first moons discovered that didn't orbit earth making them the most important piece of evidence for Copernicus' model of heliocentrism. this was tangible proof that planets other than earth had moons and that we weren't as unique as we thought.

Question 38

what is Herschel's Map?

Answer 38

Astronomer William Herschel and his sister Caroline systematically mapped the night sky, listing thousands of stars and nebulae in an almost 5 decade process. published in 1834, this map revealed the shape and size of the milky way galaxy which turned out to be disk shaped rather than a sphere.

Question 39

what else did William Herschel discover?

Answer 39

he also discovered Uranus

Question 40

what laws were obeyed in the world of astronomy before Einstein's theory of relativity and why was the theory so significant?

Answer 40

newtons 3 laws of motion were obeyed. everything changed when Einstein argued that motion was relative and that light could even be affected by gravity. The possibility that mass could warp space-time and that a large enough mass could even bend light shook the scientific community cause light was considered n absolute constant. this theory revolutionized astronomy and solved so many problems that had been deemed impossible within Newtons confining laws.

Question 41

what important discovery was made by Edwin Hubble?

Answer 41

that the universe is expanding. after tracking the movement of other galaxies(which he was also the first to discover) he concluded that they are moving away from us while also constantly accelerating. he also concluded that most of the nebulae visible in the night sky were actually galaxies which provided further evidence to support the theory of the big bang and changed our conception of the universe.

Question 42

what is Cosmic Microwave Background radiation(CMB)

Answer 42

uniformly defined radiation that filles the universe. it was discovered in 1964 by 2 bell telephone employees while working on satellite communications. since the light from an object 1 Ly away takes 1 yr to reach us, the CMB functions like a snapshot of the universe. The implications of this discovery were profound since the uniformity of the radiation appears to confirm the notion that the universe originated from a single event from which everything else follows. This fact supports the theory of the expanding universe and therefore the big bang.

Question 43

what are Extrasolar Planets?

Answer 43

also known as exoplanets, Extrasolar planets are planets found outside of our solar system. nearly 3000 have been discovered since 1988. roughly 1 in 5 sun-like stars have an earth sized planet within habitable distance from the star. assuming there are 200 billion stars in the milky way, that would mean that 11 billion habitable earth like planets exist in the milky way alone.

Question 44

name the 8 most important astronomy discoveries.

Answer 44

Earth moves around the sun, Kepler's Laws, Jupiter's moons, Herschel's Map, Theory of Relativity, The universe is expanding, Cosmic microwave background Radiation(CMB), Extrasolar Planets.