Chapter 1: Thinking like an astronomer Flashcards
Which direction does the Sun move as the year progresses from winter to summer?
North
During the summer solstice, the sun rises and sets farthest in what direction?
North
During the winter solstice, the sun rises and sets farthest in what direction?
South
Define the universe:
everything; the entirety of space and time
Define a galaxy:
a massive system of stars (and other stuff) that exists inside the universe
Define a solar system:
a star and its surrounding planets, comets, asteroids, etc… that exists inside a galaxy
Name the 8 planets of our solar system:
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune
What is our cosmic address?
Earth, Solar system, milky way galaxy, local group, virgo supercluster
What do light-years (ly) measure?
the distance light travels in 1 year
How long does it take light to travel Earth’s circumference?
1/7 second
How long does it take light to travel from Earth to the moon?
1.25 seconds
How long does it take light to travel from Earth to the sun?
8.3 minutes
How long does it take light to travel the diameter of Neptune’s orbit?
8.3 hours
How long does it take light to travel from the solar system to the nearest star?
4.2 years
How long does it take light to travel the diameter of the milky way galaxy?
100,000 years
How long does it take light to travel between the milky way galaxy and the andromeda galaxy?
2.5 million years
How long does it take light to travel the universe?
13.8 billion years
What is the speed of light? (in km/s)
300,000 km/s
Stars generate energy by what process? This process creates ____ elements. Dying stars eject those elements into space. New stars and planets (and humans) form.
nuclear fusion, heavier elements
Define the scientific method. What is the order of things?
a systematic way of testing new ideas or explanations
-observation, hypothesis, prediction, test
What is a hypothesis?
a testable explanation of the observation
What happens when your hypothesis has been falsified?
it has been proven incorrect
When does a hypothesis become a theory?
as continuing tests support a hypothesis by failing to disprove it, scientists come to accept the hypothesis as a theory
What is the cosmological principle?
The testable assumption that the same physical laws that apply here and now also apply everywhere and at all times.
What is a physical law?
theories that have become very well tested and are of fundamental importance.
What is Occam’s razor?
when we are faced with two hypotheses that explain all the observations equally well, we should use the one that requires the fewest assumptions, until we have evidence to the contrary
In terms of graphs, which variable is usually represented on the x-axis and which one is on the y-axis?
x-axis: independent variable
y-axis: dependent variable
