Astronomy Test- Laws & Gravity Flashcards
What is gravity measured in?
N = kg/m^2
what is astronomy?
the scientific study of the universe
The solar system is part of a __________.
galaxy
The galaxy in which the solar system resides is called the ___________________.
Milky Way Galaxy
What is the astronomical unit (definition)?
The average distance between the Earth and the sun.
What is the astronomical unit (distance)?
approximately 150 kilometers
What is recessional velocity?
Speed at which something is traveling away
The recessional velocity is _______ related to the _______ it is from ________.
directly, distance, earth
The more ______ the greater the gravity.
mass
The more _________, the weaker the gravity.
Distance
What is the barycenter?
The common center of mass around which two or more bodies revolve
what causes things to be attracted by gravity?
Mass (things with mass attract)
What is a binary star system?
Two stars that orbit each other
Stars in a galaxy will sometimes _______ together because they are attracted by their _______ _______ and mass.
gather, mutual gravity, mass
Who is this person?
- Very good at making observations
- Measurements were very accurate
- Believed that the sun and the mood circled the Earth (this was his own model of the universe)
TycoBrahe
Who is this person?
- Assistant
- He was not good at making observations, but he was good at taking his person’s observation and used geometry to explain the observations.
- He followed the belief of Nicholas Copernicus who aid the sun was at the center of the universe.
Johannes Kepler
What law is this?
Planets orbit in the shape of an ellipse with the start located at one focus.
Kepler’s law #1
_____________ describes how close the ellipse is to the shape of a perfect circle.
eccentricity
_____ eccentricity = oval shaped
high
______ eccentricity = nearly a perfect circle
low
What law is this?
P2=a3
P = how long it takes the planet to go around the Sun
a = the planet’s distance from the sun (the semi-major axis of the planter’s orbit)
Tells us: Planets that are far away from the Sun have longer periods than those close to the sun. They move more slowly around the sun
Kepler’s Law #3
What degree is Earth tilted at an angle of?
23.50 degrees
what is precession?
Change in direction of the axis, but without any change in tilt.
does precession affect the seasons?
No
What law is this?
A line from the plant sweeps over equal areas in equal intervals of time.
(Basically, the closer the plant is to the start, the faster it travels.)
Kepler’s Law #2
Nutation occurs over an _______ year period.
18
Why does earth’s rotation happen?
The earth is not perfectly round, but uneven like a top.
The equator _________ out because of the gravity from the ________________ pulling on it.
bulges, sun and moon
What is the formula for gravity?
G = Mass1 x Mass2 / Distance^2
