Exam 1 Flashcards
(58 cards)
What is an AU
average distance from the sun to the Earth
What is a light year
Distance light travels in one year
Put the following in order from smallest to largest:
human, universe, Galaxy, local group, Earth, Superclusters, and Solar system
Human, Earth, Solar system, Galaxy, Local group, Supercluster, and Universe
How did Aristotle know the Earth was round?
- Saw the shape of Earth’s shadow in the eclipse of the moon
- New stars become visible as you travel South
- Distant ships disappear at the bottom first
What is parallax?
An apparent shift of nearby stars with respect to distant stars as the Earth orbits the Sun
What is the “resolution” of a telescope
the smallest angular separation such that two points can be distinguished
What is the difference between heliocentric and geocentric thinking
heliocentric thinking is the thought that the planet orbits the sun while geocentric is the thought that the planets orbit Earth
What was Copernicus’ main contribution to astronomy
Challenged the Greek’s geocentric thinking
What were Galileo’s main contributions to astronomy
Discovered the 4 largest moons of Jupiter and the phases of Venus, further backing up Copernicus’ geocentric thinking
What was Tycho Brahe’s main contributions to astronomy
Collected data on the stars by making detailed, naked eye observations
What were Johannes Kepler’s contributions to astronomy
Using data collected by Brache, he came to 3 major conclusions
What is Kepler’s 1st Law?
Planets move in elliptical orbits with the Sun at one focus of the ellipse
What is Kepler’s 2nd law
The orbital speed of a planet varies so that a line joining the Sun and the planet will sweep out equal area in equal time intervals; the closer a planet is to the Sun during its orbit, the faster it moves
What is Kepler’s 3rd law
The amount of time a planet take to orbit the Sun is related to the size of its orbit; implies that a planet with a larger distance from the Sun, will take longer to orbit the Sun
What equation came out of Kepler’s 3rd law and what do the variables stand for
p^2 = a^3
a is the semimajor axis (half the diameter) and p is the time to complete orbit
What is Newton’s first law
Objects at rest tend to stay at rest while objects in motion tend to stay in motion
What are the vectors of velocity
Speed and direction
What is acceleration
speeding up/down or changing direction of velocity
What is force
anything that acts to change the velocity of an object
What is Newton’s second law
force = ma
What is Newton’s 3rd law
for any force, there is an equal and opposite reaction force
what is the equation for the momentum of an object
momentum (p) = M/v (mass divided by velocity)
How were Kepler’s 1st and 2nd law apply to orbiting objects
Found that both objects move in ellipses about a common center of mass that could be anywhere between the two objects
When an object is in orbit, what is the relationship between altitude and speed
When at higher altitude the object will slow down and vise versa
